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Hidden-charm pentaquark states through current algebra: from their production to decay

  • There may be seven ˉD()Σ()c hadronic molecular states. We construct their corresponding interpolating currents and calculate their masses and decay constants using QCD sum rules. Based on these results, we calculate their relative production rates in Λ0b decays using current algebra, that is, B(Λ0bPcK):B(Λ0bPcK), where Pc and Pc are two different states. We also study their decay properties via Fierz rearrangement and further calculate these ratios in the J/ψp mass spectrum, that is, B(Λ0bPcKJ/ψpK):B(Λ0bPcKJ/ψpK). Our results suggest that the ˉDΣc molecular states of JP=1/2 and 3/2 may be observed in future experiments.
  • Since the discovery of X(3872) by Belle in 2003 [1], many charmonium-like XYZ states have been discovered [2]. Some of these structures may contain four quarks, ˉccˉqq (q=u/d), and are therefore good candidates for hidden-charm tetraquark states.

    In recent years, the LHCb Collaboration has continuously observed as many as five interesting exotic structures:

    ● In 2015, the LHCb experiment observed two structures, Pc(4380)+ and Pc(4450)+, in the J/ψp invariant mass spectrum of the Λ0bJ/ψpK decays [3]:

    Pc(4380)+:M=4380±8±29MeV,Γ=205±18±86MeV,

    (1)

    Pc(4450)+:M=4449.8±1.7±2.5MeV,Γ=39±5±19MeV.

    (2)

    This observation was later supported by a subsequent LHCb experiment investigating the J/ψp invariant mass spectrum of the Λ0bJ/ψpπ decays [4].

    ● In 2019, the LHCb experiment observed a new structure, Pc(4312)+, and further separated Pc(4450)+ into two substructures, Pc(4440)+ and Pc(4457)+, again in the J/ψp invariant mass spectrum of the Λ0bJ/ψpK decays [5].

    Pc(4312)+:M=4311.9±0.7+6.80.6MeV,Γ=9.8±2.7+3.74.5MeV,

    (3)

    Pc(4440)+:M=4440.3±1.3+4.14.7MeV,Γ=20.6±4.9+8.710.1MeV,

    (4)

    Pc(4457)+:M=4457.3±0.6+4.11.7MeV,Γ=6.4±2.0+5.71.9MeV.

    (5)

    ● In 2020, the LHCb experiment reported evidence of a hidden-charm pentaquark state with strangeness, Pcs(4459)0, in the J/ψΛ invariant mass spectrum of the ΞbJ/ψΛK decays [6].

    Pcs(4459)0:M=4458.8±2.9+4.71.1MeV,Γ=17.3±6.5+8.05.7MeV.

    (6)

    These structures contain at least five quarks, ˉccuud or ˉccuds; therefore, they are perfect candidates for hidden-charm pentaquark states. The charmonium-like XYZ and hidden-charm pentaquark states have attracted significant attention, and studies on these states have greatly improved our understanding of the non-perturbative behaviors of the strong interaction in the low energy region [718].

    To understand the Pc and Pcs states, various theoretical interpretations have been proposed, such as loosely-bound hadronic molecular states [1940], tightly-bound compact pentaquark states [4151], and kinematical effects [5255]. In particular, the three narrow states Pc(4312)+, Pc(4440)+, and Pc(4457)+ are just below the ˉDΣc and ˉDΣc thresholds; therefore, it is natural to describe them as ˉD()Σc hadronic molecular states, whose existence was predicted in Refs. [5660] before the 2015 LHCb experiment [3]. The other narrow state, Pcs(4459)0, is just below the ˉDΞc threshold; hence, it is natural to describe it as the ˉDΞc molecular state [61, 62].

    However, these exotic structures were only observed in the LHCb experiment [36]. It is crucial to search for their partner states as well as other potential decay channels to further understand their nature. There have been several theoretical studies on this subject using, for example, effective approaches [6366], the quark interchange model [67, 68], heavy quark symmetry [69, 70], and QCD sum rules [71]. We refer to reviews [718] and the references therein for detailed discussions.

    In this paper, we systematically investigate hidden-charm pentaquark states as ˉD()Σ()c hadronic molecular states through their corresponding hidden-charm pentaquark interpolating currents. We systemically construct all the relevant currents and apply QCD sum rules to calculate their masses and decay constants. The obtained results are used to further study their production and decay properties.

    Our strategy is fairly straightforward. First, we construct a hidden-charm pentaquark current, such as

    2ξ1(x)=[δabˉca(x)γ5db(x)]×[ϵcdeuTc(x)Cγμud(x)γμγ5ce(x)],

    (7)

    where ae are color indices. This is the best coupling of the current to the DΣ++c molecular state of JP=1/2 through

    0|ξ1|DΣ++c;1/2(q)=f1u(q),

    (8)

    where u(q) is the Dirac spinor of |DΣ++c;1/2. Its decay constant f1 can be calculated using QCD sum rules.

    Second, we investigate three-body Λ0bJ/ψpK decays. The total quark content of the final states is udcˉcsˉuu, where the intermediate states D()Σ()++cK can be produced. We apply Fierz rearrangement to carefully examine the combination of these seven quarks, from which we select the current ξ1 and evaluate the relative production rate of |DΣ++c;1/2.

    Third, we apply the Fierz rearrangement of the Dirac and color indices to transform the current ξ1 into

    2ξ116[ˉcaγ5ca]N112[ˉcaγμca]γμγ5N+,

    (9)

    where N=ϵabc(uTaCdb)γ5ucϵabc(uTaCγ5db)uc is Ioffe's light baryon field coupling to a proton [7274]. Accordingly, ξ1 couples to the ηcp and J/ψp channels simultaneously:

    0|ξ1|ηcp2120|ˉcaγ5ca|ηc0|N|p+,0|ξ1|ψp2240|ˉcaγμca|ψγμγ50|N|p+.

    (10)

    We can use these two equations to straightforwardly calculate the relative branching ratio of the |DΣ++c;1/2 decay into ηcp to its decay into J/ψp [75]. We refer to Ref. [76] for detailed discussions. There, we applied the same method to study the decay properties of Pc(4312)+, Pc(4440)+, and Pc(4457)+ as ˉD()Σc molecular states, and in this paper, we apply it to study the decay properties of the ˉD()Σc molecular states.

    This paper is organized as follows. In Sec. II, we systematically construct the hidden-charm pentaquark currents corresponding to the ˉD()Σ()c hadronic molecular states. We use them to perform QCD sum rule analyses in Sec. III and calculate their masses and decay constants. The obtained results are used in Sec. IV to study their production in Λ0b decays using current algebra. In Sec. V, we use the Fierz rearrangement of the Dirac and color indices to study the decay properties of the ˉD()Σc molecular states and calculate several of their relative branching ratios. The obtained results are summarized and discussed in Sec. VI.

    In this section, we use the ˉc, c, u, u, and d (q=u/d) quarks to construct hidden-charm pentaquark interpolating currents. We consider the following three types of currents:

    θ(x)=[ˉca(x)Γθ1cb(x)][[qTc(x)CΓθ2qd(x)]Γθ3qe(x)],η(x)=[ˉca(x)Γη1ub(x)][[uTc(x)CΓη2dd(x)]Γη3ce(x)],ξ(x)=[ˉca(x)Γξ1db(x)][[uTc(x)CΓξ2ud(x)]Γξ3ce(x)],

    (11)

    where ae are color indices, Γθ/η/ξ1/2/3 are Dirac matrices, and C=iγ2γ0 is the charge-conjugation operator. We illustrate these in Fig. 1. These three configurations can be related using Fierz rearrangement in Lorentz space and color rearrangement.

    Figure 1

    Figure 1.  (color online) Three types of hidden-charm pentaquark interpolating currents, θ(x), η(x), and ξ(x). Quarks are shown in red/green/blue, and antiquarks are shown in cyan/magenta/yellow. Taken from Ref. [76].

    δabϵcde=δacϵbde+δadϵcbe+δaeϵcdb.

    (12)

    This is discussed in detail in Sec. V, where we construct the θ(x) currents by combining charmonium operators and light baryon fields.

    In this section, we construct the η(x) and ξ(x) currents and use them to construct currents corresponding to the ˉD()Σ()c hadronic molecular states. To achieve this, we combine charmed meson operators and charmed baryon fields. There are five independent charmed meson operators:

    ˉcaqa[0+],ˉcaγ5qa[0],ˉcaγμqa[1],ˉcaγμγ5qa[1+],ˉcaσμνqa[1±].

    (13)

    There is another, ˉcdσμνγ5qd; however, it is related to ˉcdσμνqd through

    σμνγ5=i2ϵμνρσσρσ.

    (14)

    In particular, we require the JP=0 and 1 operators to construct the η(x) and ξ(x) currents, which couple to the ground-state charmed mesons D=D/D.

    JD=ˉcaγ5qa,JD=ˉcaγμqa.

    (15)

    Charmed baryon fields have been systematically constructed and studied in Refs. [7780] using the method of QCD sum rules [81, 82] within heavy quark effective theory [8385]. In this paper, we require the following charmed baryon fields, JB, which couple to the ground-state charmed baryons B=Λc/Σc/Σc:

    JΛ+c=ϵabc[uTaCγ5db]cc,2JΣ++c=ϵabc[uTaCγμub]γμγ5cc,JΣ+c=ϵabc[uTaCγμdb]γμγ5cc,2JΣ0c=ϵabc[dTaCγμdb]γμγ5cc,2JαΣ++c=ϵabcPαμ3/2[uTaCγμub]cc,JαΣ+c=ϵabcPαμ3/2[uTaCγμdb]cc,2JαΣ0c=ϵabcPαμ3/2[dTaCγμdb]cc.

    (16)

    Here, Pμν3/2 is the spin-3/2 projection operator

    Pμν3/2=gμν14γμγν.

    (17)

    In the molecular picture, Pc(4312)+, Pc(4440)+, and Pc(4457)+ are usually interpreted as the ˉDΣc and ˉDΣc hadronic molecular states [20, 21, 60]. Their relevant currents have been constructed in Ref. [76]. In this paper, we further construct the ˉDΣc and ˉDΣc currents; they are all summarized here for completeness.

    Altogether, there can be seven ˉD()Σ()c hadronic molecular states, which are ˉDΣc of JP=1/2, ˉDΣc of JP=(1/2)/(3/2), ˉDΣc of JP=3/2, and ˉDΣc of JP=(1/2)/(3/2)/(5/2):

    |ˉDΣc;1/2;θ=cosθ|ˉD0Σ+c;1/2+sinθ|DΣ++c;1/2,

    (18)

    |ˉDΣc;1/2;θ=cosθ|ˉD0Σ+c;1/2+sinθ|DΣ++c;1/2,

    (19)

    |ˉDΣc;3/2;θ=cosθ|ˉD0Σ+c;3/2+sinθ|DΣ++c;3/2,

    (20)

    |ˉDΣc;3/2;θ=cosθ|ˉD0Σ+c;3/2+sinθ|DΣ++c;3/2,

    (21)

    |ˉDΣc;1/2;θ=cosθ|ˉD0Σ+c;1/2+sinθ|DΣ++c;1/2,

    (22)

    |ˉDΣc;3/2;θ=cosθ|ˉD0Σ+c;3/2+sinθ|DΣ++c;3/2,

    (23)

    |ˉDΣc;5/2;θ=cosθ|ˉD0Σ+c;5/2+sinθ|DΣ++c;5/2,

    (24)

    where θ is an isospin parameter satisfying θ=55o for I=1/2 and θ=35o for I=3/2. In the present study, we concentrate on the former I=1/2 states, so that we may simplify the notations to

    |ˉD()Σ()c;JP=1/3|ˉD()0Σ()+c;JP2/3|D()Σ()++c;JP.

    (25)

    Their relevant interpolating currents are

    Ji=cosθηi+sinθξi,

    (26)

    where

    η1=[δabˉcaγ5ub][ϵcdeuTcCγμddγμγ5ce]=ˉD0Σ+c,

    (27)

    η2=[δabˉcaγνub]γνγ5[ϵcdeuTcCγμddγμγ5ce]=ˉD0νγνγ5Σ+c,

    (28)

    ηα3=Pαν3/2[δabˉcaγνub][ϵcdeuTcCγμddγμγ5ce]=Pαν3/2ˉD0νΣ+c,

    (29)

    ηα4=[δabˉcaγ5ub]Pαμ3/2[ϵcdeuTcCγμddce]=ˉD0Σ+;αc,

    (30)

    η5=[δabˉcaγνub]Pνμ3/2[ϵcdeuTcCγμddce]=ˉD0νΣ+;νc,

    (31)

    ηα6=[δabˉcaγνub]Pαρ3/2γνγ5P3/2ρμ[ϵcdeuTcCγμddce]=ˉD0νPαρ3/2γνγ5Σ+c;ρ,

    (32)

    ηαβ7=Pαβ,νρ5/2[δabˉcaγνub]P3/2ρμ[ϵcdeuTcCγμddce]=Pαβ,νρ5/2ˉD0νΣ+c;ρ,

    (33)

    and

    ξ1=12[δabˉcaγ5db][ϵcdeuTcCγμudγμγ5ce]=DΣ++c,

    (34)

    ξ2=12[δabˉcaγνdb]γνγ5[ϵcdeuTcCγμudγμγ5ce]=Dνγνγ5Σ++c,

    (35)

    ξα3=12Pαν3/2[δabˉcaγνdb][ϵcdeuTcCγμudγμγ5ce]=Pαν3/2DνΣ++c,

    (36)

    ξα4=12[δabˉcaγ5db]Pαμ3/2[ϵcdeuTcCγμudce]=DΣ++;αc,

    (37)

    ξ5=12[δabˉcaγνdb]Pνμ3/2[ϵcdeuTcCγμudce]=DνΣ++;νc,

    (38)

    ξα6=12[δabˉcaγνdb]Pαρ3/2γνγ5P3/2ρμ[ϵcdeuTcCγμudce]=DνPαρ3/2γνγ5Σ++c;ρ,

    (39)

    ξαβ7=12Pαβ,νρ5/2[δabˉcaγνdb]P3/2ρμ[ϵcdeuTcCγμudce]=Pαβ,νρ5/2DνΣ++c;ρ.

    (40)

    In the above expressions, we use D and B to denote the charmed meson operators JD and charmed baryon fields JB for simplicity; Pμν,ρσ5/2 is the spin-5/2 projection operator

    Pμν,ρσ5/2=12gμρgνσ+12gμσgνρ16gμνgρσ112gμργνγσ112gμσγνγρ112gνσγμγρ112gνργμγσ.

    (41)

    In this section, we use QCD sum rules [81, 82] to study ˉD()Σ()c molecular states through the currents J17, that is, J1,2,5 of JP=1/2, Jα3,4,6 of JP=3/2, and Jαβ7 of JP=5/2. We calculate their masses and decay constants, and the obtained results are used in the next section to further calculate their relative production rates. Several of these calculations have been performed in Refs. [19, 8688], and we refer to Refs. [3840, 50, 61] for more relevant QCD sum rule studies.

    We assume that the currents J17 couple to the ˉD()Σ()c molecular states X17 through

    0|J1,2,5|X1,2,5;1/2=fX1,2,5u(p),0|Jα3,4,6|X3,4,6;3/2=fX3,4,6uα(p),0|Jαβ7|X7;5/2=fX7uαβ(p),

    (42)

    where u(p), uα(p), and uαβ(p) are spinors of X17. The two-point correlation functions extracted from these currents can be written as

    Π1,2,5(q2)=id4xeiqx0|T[J1,2,5(x)ˉJ1,2,5(0)]|0=(+MX1,2,5)Π1,2,5(q2),

    (43)

    Παα3,4,6(q2)=id4xeiqx0|T[Jα3,4,6(x)ˉJα3,4,6(0)]|0=Gαα3/2(+MX3,4,6)Π3,4,6(q2),

    (44)

    Παβ,αβ7(q2)=id4xeiqx0|T[Jαβ7(x)ˉJαβ7(0)]|0=Gαβ,αβ5/2(+MX7)Π7(q2),

    (45)

    where Gμν3/2 and Gμν,ρσ5/2 are coefficients of the spin-3/2 and spin-5/2 propagators, respectively.

    Gμν3/2(p)=gμν13γμγνpμγνpνγμ3m2pμpν3m2,

    (46)

    Gμν,ρσ5/2(p)=12(gμρgνσ+gμσgνρ)15gμνgρσ110(gμργνγσ+gμσγνγρ+gνργμγσ+gνσγμγρ)

    +110m(gμρ(pνγσpσγν)+gμσ(pνγρpργν)+gνρ(pμγσpσγμ)+gνσ(pμγρpργμ))+15m2(gμνpρpσ+gρσpμpν)25m2(gμρpνpσ+gμσpνpρ+gνρpμpσ+gνσpμpρ)+110m2(γμpν(γρpσ+γσpρ)+γνpμ(γρpσ+γσpρ))+15m3(pρpσ(γμpν+γνpμ)pμpν(γρpσ+γσpρ))+25m4pμpνpρpσ.

    (47)

    In the above expressions, we assume that the states X17 have the same spin-parity quantum numbers as the currents J17 so that we may use the "non-γ5 coupling" in Eq. (42). Conversely, we must use the "γ5 coupling,"

    0|J17|X17=fX17γ5u(p),

    (48)

    if the states X17 have an opposite parity to the currents J17. We may alternatively use the partner currents γ5J17, which also have opposite parity.

    0|γ5J17|X17=fX17γ5u(p).

    (49)

    From Eqs. (48) and (49), we can derive another "non-γ5 coupling" between γ5J17 and X17, expressed as

    0|γ5J17|X17=fX17u(p).

    (50)

    We refer to Refs. [8992] for detailed discussions.

    The two-point correlation functions derived from Eqs. (48) and (49) are similar to Eqs. (43)–(45) but with (+MX) replaced by (+MX). Based on this feature, we can extract the parities of X17; we use the terms proportional to 1 to evaluate the masses of X17, which are then compared with the terms proportional to to extract their parities.

    In QCD sum rule studies, we must calculate the two-point correlation function Π(q2) at both the hadron and quark-gluon levels. At the hadron level, we use the dispersion relation to express this as

    Π(q2)=1πs<ImΠ(s)sq2iεds,

    (51)

    with s< the physical threshold. We define the imaginary part of the correlation function as the spectral density ρ(s), which can be evaluated at the hadron level by inserting the intermediate hadron states n|nn|as follows:

    ρphen(s)ImΠ(s)/π=nδ(sM2n)0|η|nn|η|0=f2Xδ(sm2X)+continuum.

    (52)

    In the last step, we adopt typical parametrization of one-pole dominance for the ground state X along with a continuum contribution.

    At the quark-gluon level, we calculate Π(q2) using the method of operator product expansion (OPE) and extract its corresponding spectral density ρOPE(s). After performing the Borel transformation at both the hadron and quark-gluon levels, we approximate the continuum using the spectral density above a threshold value s0 (quark-hadron duality) and arrive at the sum rule equation

    Π(s0,M2B)f2XeM2X/M2B=s0s<es/M2BρOPE(s)ds.

    (53)

    This can be used to further calculate MX and fX through

    M2X(s0,MB)=s0s<es/M2BsρOPE(s)dss0s<es/M2BρOPE(s)ds,

    (54)

    f2X(s0,MB)=e(M2X(s0,MB))/M2Bs0s<es/M2BρOPE(s)ds.

    (55)

    In this study, we calculate OPEs at the leading order of αs and up to the D(imension)=10 terms, including the perturbative term, charm quark mass, quark condensate ˉqq,gluon condensate g2sGG, quark-gluon mixed condensate gsˉqσGq, and their combinations ˉqq2, ˉqqgsˉqσGq, ˉqq3, and gsˉqσGq2. We summarize the obtained spectral densities ρ17(s) in Appendix A, which are extracted from the currents J17, respectively.

    In these calculations, we ignore chirally suppressed terms with light quark masses and adoptthe factorization assumption of vacuum saturation for higher dimensional condensates, that is, (ˉqq)2=ˉqq2, (ˉqq)(gsˉqσGq)=ˉqqgsˉqσGq, (ˉqq)3=ˉqq3, and (gsˉqσGq)2=gsˉqσGq2. We find that the D=3 quark condensate ˉqq and the D=5 mixed condensate gsˉqσGq are both multiplied by the charm quark mass mcand are thus important power corrections.

    In the following subsection, we use the spectral densities ρ17(s) to perform numerical analyses and calculate the masses and decay constants of X17. First, however, let us investigate the current J1 as an example. This has the quantum number JP=1/2 and couples to the ˉDΣc molecular state X1. Its spectral density ρ1(s) is given in Eq. (A1). We find that the terms multiplied by mc are almost positively proportional to the terms multiplied by . Hence, the extracted parity of X1 is found to be negative, which is the same as J1. In other words, J1 mainly couples to a negative-parity state. Similarly, all the ˉD()Σ()c molecular states defined in Eqs. (18)–(24) are found to have negative parity.

    In this subsection, we use the spectral densities ρ17(s) extracted from the currents J17 to perform numerical analyses and calculate the masses and decay constants of X17. As discussed in the previous subsection, we only use the terms proportional to mc to achieve this.

    We use the current J1 as an example, whose spectral density ρ1(s) can be found in Eq. (A1), and apply the following QCD sum rule parameter values [93101]:

    mc=1.275+0.0250.035GeV,ˉqq=(0.24±0.01)3GeV3,g2sGG=(0.48±0.14)GeV4,gsˉqσGq=M20×ˉqq,M20=(0.8±0.2)GeV2,

    (56)

    where the running mass in the ¯MS scheme is used for the charm quark.

    There are two free parameters in Eqs. (54) and (55), the Borel mass MB and threshold value s0. We use two criteria to constrain the Borel mass MB for a fixed s0. The first criterion is to ensure the convergence of the OPE series. This is achieved by requiring the D=10 terms (mcˉqq3 and gsˉqσGq2) to be less than 10% so that the lower limit of MB can be determined.

    Convergence|ΠD=10(,MB)Π(,MB)|10%.

    (57)

    We show this function in Fig. 2 using the solid curve and find that OPE convergence improves with increasing MB. This criterion leads to (MminB)2=3.27 GeV2 when setting s0=24 GeV2.

    Figure 2

    Figure 2.  Convergence (solid curve, defined in Eq. (57)) and pole-contribution (dashed curve, defined in Eq. (58)) as functions of the Borel mass MB. These curves are obtained using the current J1 when setting s0=24 GeV2.

    The second criterion is to ensure the validity of one-pole parametrization. This is achieved by requiring the pole contribution to be larger than 40% so that the upper limit of MB can be determined.

    PoleContributionΠ(s0,MB)Π(,MB)40%.

    (58)

    We show this function in Fig. 2 using the dashed curve and find that it decreases with increasing MB. This criterion leads to (MmaxB)2=3.52 GeV2 when setting s0=24 GeV2.

    Altogether, we extract the working region of the Borel mass to be 3.27 <M2B<3.52 GeV2 for the current J1 with the threshold value s0=24 GeV2. We show variations in MX1 and fX1 with respect to the Borel mass MB in Fig. 3. They are shown in a broader region, 3.0 M2B4.0 GeV2, and are more stable inside the above Borel window.

    Figure 3

    Figure 3.  Variations in the mass MX (left) and decay constant fX (right) with respect to the Borel mass MB, calculated using the current J1. In both panels, the short-dashed, solid, and long-dashed curves are obtained by setting s0=23, 24, and 25 GeV2, respectively.

    Redoing the same procedures by changing s0, we find that there are non-vanishing Borel windows as long as s0smin0=22.4 GeV2. Accordingly, we choose s0 to be slightly larger with an uncertainty of ±1.0 GeV, that is, s0=24.0±1.0 GeV2. Overall, our working regions for the current J1 are determined to be 23.0 s025.0 GeV2 and 3.27 M2B3.52 GeV2, for which we calculate the mass and decay constant of X1 to be

    MX1=4.30+0.100.10GeV,fX1=(1.19+0.190.18)×103GeV6.

    (59)

    Here, the central values correspond to M2B=3.40 GeV2 and s0=24.0 GeV2. Their uncertainties originate from the threshold value s0, Borel mass MB, charm quark mass mc, and various QCD sum rule parameters listed in Eq. (56). This mass value is consistent with the experimental mass of Pc(4312)+ [5], revealing it to be the I=1/2ˉDΣc molecular state of JP=1/2.

    Similarly, we use the spectral densities ρ27(s) extracted from the currents J27 to perform numerical analyses and calculate the masses and decay constants of X27. In particular, the sum rule results extracted from the currents Jα6 and Jαβ7 are

    MX6=4.64+0.100.10GeV,fX6=(1.01+0.150.14)×103GeV6,MX7=4.64+0.140.12GeV,fX7=(0.77+0.120.11)×103GeV6.

    (60)

    These two mass values are both close to, but slightly larger than, the ˉDΣc threshold at MD+MΣc=4527 MeV. To obtain a better description of the ˉDΣc molecular states that may lie just below the ˉDΣc threshold, we loosen the criterion given in Eq. (57) to

    Convergence|ΠD=10(,MB)Π(,MB)|15%.

    (61)

    Now, the masses and decay constants extracted from the currents Jα6 and Jαβ7 are modified to be

    bMX6=4.52+0.110.11GeV,fX6=(0.85+0.140.13)×103GeV6,MX7=4.55+0.150.13GeV,fX7=(0.65+0.110.10)×103GeV6.

    (62)

    Moreover, the mass of |ˉDΣc;3/2 is calculated to be 4.43+0.100.10 GeV, which is consistent with, but also slightly larger than, the ˉDΣc threshold at MD+MΣc=4385 MeV. All these divergences indicate that the accuracy of our QCD sum rule results is moderate but not good enough to extract the binding energies of the ˉD()Σ()c molecular states. Therefore, our results can suggest but not determine a) whether these ˉD()Σ()c molecular states exist, and b) whether they are bound or resonance states. However, in this study, we are more concerned with the ratios, that is, the relative production rates and relative branching ratios, whose uncertainties can be significantly reduced. Accordingly, the decay constants fX calculated in this section are input parameters that are more important than the masses MX. Note that the decay constants fX can also be used within the QCD sum rule method to directly calculate the partial decay widths through the three-point correlation functions; however, we do not perform this in the present study.

    We summarize all the above sum rule results in Table 1. Our results are consistent with those of Ref. [102], where the authors applied the same QCD sum rule method to study both the I=1/2ˉD()Σ()c and I=3/2 molecular states. Our results support the interpretations of Pc(4440)+ and Pc(4457)+ [5] as the I=1/2ˉDΣc molecular states of JP=1/2 and 3/2. Again, the accuracy of our sum rule results is not good enough to distinguish or identify them. To better understand them, we study their production and decay properties in the following sections, where we find that Pc(4440)+ and Pc(4457)+ can be better interpreted in our framework as |ˉDΣc;3/2 and |ˉDΣc;1/2, respectively.

    Table 1

    Table 1.  Masses and decay constants of X17 extracted from the currents J17.
    CurrentsConfigurationsmin0/GeV2Working regionsPole (%)Mass/GeVfX/GeV6Candidate
    s0/GeV2M2B/GeV2
    J1|ˉDΣc;1/222.424.0±1.03.273.5240484.30+0.100.10(1.19+0.190.18)×103Pc(4312)+
    J2|ˉDΣc;1/225.527.0±1.03.783.9940464.48+0.100.10(2.24+0.340.30)×103Pc(4457)+
    J3|ˉDΣc;3/224.626.0±1.03.513.7240464.46+0.110.10(1.15+0.180.16)×103Pc(4440)+
    J4|ˉDΣc;3/224.225.0±1.03.333.4540444.43+0.100.10(0.65+0.110.10)×103
    J5|ˉDΣc;1/226.027.0±1.03.433.5640444.51+0.100.11(1.12+0.190.17)×103
    J6|ˉDΣc;3/225.327.0±1.03.693.9840484.52+0.110.11(0.85+0.140.13)×103
    J7|ˉDΣc;5/224.726.0±1.03.223.4240464.55+0.150.13(0.65+0.110.10)×103
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    In this section, we study the production of the ˉD()Σ()c molecular states in Λ0b decays using current algebra. We calculate their relative production rates, that is, B(Λ0bPcK):B(Λ0bPcK), with Pc and Pc as two different states. We refer to Refs. [103, 104] for additional relevant studies.

    Pc(4312)+, Pc(4440)+, and Pc(4457)+ were observed by the LHCb in the J/ψp invariant mass spectrum of Λ0bJ/ψpK decays. The quark content of the initial state Λ0b is udb. In this three-body decay process, the b quark first decays into a c quark by emitting a W boson, and the W boson translates into a pair of ˉc and s quarks, both of which are Cabibbo-favored. Then, they obtain a pair of ˉu and u quarks from the vacuum. Finally, they hadronize into the three final states J/ψpK.

    Λ0b=udbudcˉcsudcˉcsˉuuJ/ψpK.

    (63)

    Hence, the total quark content of the final states is udcˉcsˉuu, where the intermediate states D()Σ()++cK and ˉD()0Σ()+cK can also be produced.

    We study the production of theˉD()Σ()c molecular states by investigating the mechanisms depicted in Fig. 4. Note that the u quark from the vacuum must exchange with either the u or d quark of Λ0b because the ud pair of Λ0b is in a state of I=0, whereas Σc and Σc both have I=1.

    Figure 4

    Figure 4.  Production mechanisms of the ˉD()Σ()c molecular states in Λ0b decays.

    As depicted in Fig. 4, the weak interaction only involves the initial b quark and the final cˉcs quarks. Hence, by considering the quark pair produced from the vacuum to be ˉuu+ˉdd of I=0, the isospin of the entire process is also conserved at I=0.

    Λ0budcˉcs(ˉuu+ˉdd)13D()Σ()++cK+13ˉD()0Σ()0cˉK016D()Σ()+cˉK016ˉD()0Σ()+cK.

    (64)

    The four fixed isospin factors allow us to consider only the D()Σ()++cK final state because the results derived from the ˉD()0Σ()+cK final state are the same. Accordingly, we only need to consider the exchange of the u quark from the vacuum and the d quark from Λ0b, which are depicted in Fig. 4(a).

    Summarizing the above discussions, in this section, we calculate the relative production rates of the ˉD()Σ()c molecular states in Λ0b decays by investigating three-body Λ0bD()Σ()++cK decays, whose mechanism is depicted in Fig. 4(a). We develop a Fierz rearrangement to describe this process in Sec. IV.A and use it to perform numerical analyses in Sec. IV.B.

    To describe the production mechanism depicted in Fig. 4(a), we use the color rearrangement given in Eq. (12) twice to obtain

    ϵabcδdeδfg=(ϵebcδda+ϵaecδdb+ϵabeδdc)×δfg=ϵgbcδdaδfe+ϵegcδdaδfb+ϵebgδdaδfc+ϵgecδdbδfa+ϵagcδdbδfe+ϵaegδdbδfc+ϵgbeδdcδfa+ϵageδdcδfb+ϵabgδdcδfe.

    (65)

    Given the initial color structure

    [ϵabcuadbcc][δdeˉcdse][δfgˉufug]

    we require the fifth to be

    [ϵagcuaugcc][δdbˉcddb][δfeˉufse]

    which corresponds to the D()Σ()++cK final state.

    Furthermore, we must apply Fierz transformation twice to (a) interchange the db and ug quarks and (b) interchange the db and se quarks. Note that Fierz rearrangement in Lorentz space is a matrix identity. It is valid if each quark field in the initial and final currents is at the same location.

    The key formula is as follows:

    Λ0bJΛ0b=[ϵabcuTaCγ5dbbc],

    (66)

    weak[ϵabcuTaCγ5dbγρ(1γ5)cc]×[δdeˉcdγρ(1γ5)se],

    (67)

    QPC[ϵabcuTaCγ5dbγρ(1γ5)cc]×[δdeˉcdγρ(1γ5)se]×[δfgˉufug],

    (68)

    color__ϵagcδdbδfe×uTaCγ5dbγρ(1γ5)cc×ˉcdγρ(1γ5)se×ˉufug+,

    (69)

    Fierz:dbug__δdbδfe4×[ϵagcuTaCγμugγρ(1γ5)cc]×ˉcdγρ(1γ5)se×ˉufγμγ5db+,

    (70)

    Fierz:dbse__+1+γ516×[ϵagcuTaCγμugγμγ5cc]×[δdbˉcdγ5db]×[δfeˉufγ5se]+(1+γ5)(gνρiσνρ)32×[ϵagcuTaCγμugγμγ5cc]×[δdbˉcdγνdb]×[δfeˉufγργ5se]+(1+γ5)(gανγρ+gαργν)16×[P3/2αμϵagcuTaCγμugcc]×[δdbˉcdγνdb]×[δfeˉufγργ5se]+,

    (71)

    __+1+γ582×ξ1×[ˉuaγ5sa]+(1+γ5)(gνρiσνρ)162(ξν314γνγ5ξ2)[ˉuaγργ5sa]+(1+γ5)(gανγρ+gαργν)82(ξαν719γαγ5ξν619γνγ5ξα6+29gανξ5)[ˉuaγργ5sa]+.

    (72)

    A brief explanation is given as follows:

    ● Eq. (67) describes the Cabibbo-favored weak decay of bc+ˉcs via the V-A current.

    ● Eq. (68) describes the production of the ˉu and u quark pair from the vacuum via the 3P0 quark pair creation mechanism.

    ● In Eq. (69), we apply the double-color rearrangement given in Eq. (65).

    ● In Eq. (70), we apply Fierz transformation to interchange the db and ug quarks.

    ● In Eq. (71), we apply Fierz transformation to interchange the db and se quarks.

    ● In Eq. (72), we combine the five uaugccˉcddb quarks so that the D()Σ()++c molecular states can be produced.

    In the above expression, we only consider ξ17 defined in Eqs. (34)–(40), which couple to the D()Σ()++c molecular states through an S-wave. In reality, there may be other currents coupling to these states through a P-wave, which are not included in the present study, such as

    ξαβ6=12Pαβ,νρ3/2[δabˉcaγνdb]P3/2ρμ[ϵcdeuTcCγμudce]=Pαβ,νρ3/2DνΣ++c;ρ,

    (73)

    where Pμν,ρσ3/2 is the spin-3/2 projection operator with two antisymmetric Lorentz indices,

    Pμν,ρσ3/2=12gμρgνσ12gμσgνρ+16σμνσρσ14gμργνγσ+14gμσγνγρ14gνσγμγρ+14gνργμγσ.

    (74)

    The current ηαβ6 couples to |DΣ++c;3/2 through

    0|ηαβ6|DΣ++c;3/2=ifT6(pαuβpβuα),

    (75)

    where uα is the spinor of |DΣ++c;3/2. It can also couple to another state of JP=3/2+.

    Consequently, |ˉDΣc;3/2 may still be produced in Λ0b decays, although its directly corresponding current ξα4 (and hence Jα4) does not appear in Eq. (72). Additionally, omission of the "other possible currents" produces theoretical uncertainties.

    In this subsection, we use the Fierz rearrangement given in Eq. (72) to perform numerical analyses. We consider the isospin factors of Eqs. (25) and (64) and directly calculate the relative production rates of the I=1/2ˉD()Σ()c molecular states in Λ0b decays. To achieve this, we require the following couplings to K:

    0|ˉuaγ5sa|K(q)=λK,0|ˉuaγμγ5sa|K(q)=iqμfK,

    (76)

    where fK=155.6 MeV [2], and λK=f2KmKmu+ms.

    We extract from Eq. (72) the following decay channels:

    1. The decay of Λ0b into |ˉDΣc;1/2K is contributed by ξ1×[ˉuaγ5sa].

    Λ0b(q)|ˉDΣc;1/2(q1)K(q2)ciλKf|ˉDΣc;1/2ˉuΛ0b(1+γ516)u,

    (77)

    where uΛ0b and u are spinors of Λ0b and |ˉDΣc;1/2, respectively. The decay constant f|ˉDΣc;1/2 has been calculated in the previous section and given in Table 1. The overall factor c is related to a) the coupling of JΛ0b to Λ0b, b) the weak and 3P0 decay processes described by Eqs. (67) and (68), and c) the isospin factors of Eqs. (25) and (64). We use the same factor c for all seven ˉD()Σ()c molecular states. This can cause a significant theoretical uncertainty, which is not taken into account in this study.

    2. The decay of Λ0b into |ˉDΣc;1/2K is contributed by ξ2×[ˉuaγργ5sa].

    Λ0b(q)|ˉDΣc;1/2(q1)K(q2)cifKf|ˉDΣc;1/2qρ2×ˉuΛ0b((1+γ5)(gνρiσνρ)32(14γνγ5))u,

    (78)

    where u and f|ˉDΣc;1/2 are the spinor and decay constant of |ˉDΣc;1/2, respectively.

    3. The decay of Λ0b into |ˉDΣc;3/2K is contributed by ξν3×[ˉuaγργ5sa].

    Λ0b(q)|ˉDΣc;3/2(q1)K(q2)cifKf|ˉDΣc;3/2qρ2×ˉuΛ0b((1+γ5)(gνρiσνρ)32)uν,

    (79)

    where uν and f|ˉDΣc;3/2 are the spinor and decay constant of |ˉDΣc;3/2, respectively.

    4. The decay of Λ0b into |ˉDΣc;1/2K is contributed by ξ5×[ˉuaγργ5sa]:

    Λ0b(q)|ˉDΣc;1/2(q1)K(q2)cifKf|ˉDΣc;1/2qρ2×ˉuΛ0b((1+γ5)(gανγρ+gαργν)1629gαν)u,

    (80)

    where u and f|ˉDΣc;1/2 are the spinor and decay constant of |ˉDΣc;1/2, respectively.

    5. The decay of Λ0b into |ˉDΣc;3/2K is contributed by ξβ6×[ˉuaγργ5sa].

    Λ0b(q)|ˉDΣc;3/2(q1)K(q2)cifKf|ˉDΣc;3/2qρ2×ˉuΛ0b((1+γ5)(gανγρ+gαργν)16×(19γαγ5gνβ19γνγ5gαβ))uβ,

    (81)

    where uβ and f|ˉDΣc;3/2 are the spinor and decay constant of |ˉDΣc;3/2, respectively.

    6. The decay of Λ0b into |ˉDΣc;5/2K is contributed by ξαν7×[ˉuaγργ5sa].

    Λ0b(q)|ˉDΣc;5/2(q1)K(q2)cifKf|ˉDΣc;5/2qρ2×ˉuΛ0b((1+γ5)(gανγρ+gαργν)16)uαν,

    (82)

    where uαν and f|ˉDΣc;5/2 are the spinor and decay constant of |ˉDΣc;5/2, respectively.

    We find that Pc(4312)+, Pc(4440)+, and Pc(4457)+ can be well interpreted in our framework as |ˉDΣc;1/2, |ˉDΣc;3/2, and |ˉDΣc;1/2, respectively. Accordingly, we assume the masses of the ˉD()Σ()c molecular states to be

    M|ˉDΣc;1/2=MPc(4312)+=4311.9MeV,M|ˉDΣc;1/2=MPc(4457)+=4457.3MeV,M|ˉDΣc;3/2=MPc(4440)+=4440.3MeV,M|ˉDΣc;3/2MD+MΣc=4385MeV,M|ˉDΣc;1/2MD+MΣc=4527MeV,M|ˉDΣc;3/2MD+MΣc=4527MeV,M|ˉDΣc;5/2MD+MΣc=4527MeV.

    (83)

    Now, we can summarize the above production amplitudes to obtain the following partial decay widths:

    Γ(Λ0b|ˉDΣc1/2K)=c26.15×1011GeV17,Γ(Λ0b|ˉDΣc1/2K)=c28.76×1012GeV17,Γ(Λ0b|ˉDΣc3/2K)=c27.52×1012GeV17,Γ(Λ0b|ˉDΣc3/2K)=0Γ(Λ0b|ˉDΣc1/2K)=c23.57×1011GeV17,Γ(Λ0b|ˉDΣc3/2K)=c21.38×1012GeV17,Γ(Λ0b|ˉDΣc5/2K)=0.

    (84)

    From these values, we derive the following relativeproduction rates, R1(Pc)B(Λ0bPcK)/B(Λ0b|ˉDΣc3/2K):

    B(Λ0bK(|ˉDΣc1/2:|ˉDΣc1/2:|ˉDΣc3/2:|ˉDΣc3/2:|ˉDΣc1/2:|ˉDΣc3/2:|ˉDΣc5/2))B(Λ0b|ˉDΣc3/2K)8.2:1.2:1:0:4.8:0.18:0.

    (85)

    We have applied the Fierz rearrangement [105] of the Dirac and color indices to study the decay properties of Pc(4312)+, Pc(4440)+, and Pc(4457)+ as ˉD()Σc molecular states based on the currents J13 [76]. In this section, we follow the same procedures to study the decay properties of the ˉD()Σc molecular states using the currents J47. We study their decays into charmonium mesons and spin-1/2 light baryons as well as charmed mesons and spin-1/2 charmed baryons, such as J/ψp and ˉDΛc.

    We refer to Ref. [76] for detailed discussions. This method has been applied to study the strong decay properties of Zc(3900), X(3872), and X(6900) in Refs. [106108], and a similar arrangement of spin and color indices in the nonrelativistic case has been applied to study the decay properties of the XYZ and Pc states in Refs. [67, 69, 109113].

    To study the decays of the ˉD()Σc molecular states into charmonium mesons and light baryons, we must use the θ(x) currents. We can construct them by combining charmonium operators and light baryon fields, as done in Ref. [76]. In the present study, we require couplings of charmonium operators to charmonium states, which are listed in Table 2. We also require Ioffe's light baryon field [7274, 114118]

    Table 2

    Table 2.  Couplings of meson operators to meson states, where color indices are omitted for simplicity. Taken from Ref. [106].
    Operators IGJPC Mesons IGJPC Couplings Decay constants
    IS=ˉcc0+0++χc0(1P)0+0++0|IS|χc0=mχc0fχc0fχc0=343 MeV [120]
    IP=ˉciγ5c0+0+ηc0+0+0|IP|ηc=ληcληc=(fηcm2ηc)/(2mc)
    IVμ=ˉcγμc 0^-1^{–} J/\psi 0^-1^{–} \langle0| I^{V}_\mu | J/\psi \rangle = m_{J/\psi} f_{J/\psi} \epsilon_\mu f_{J/\psi} = 418 MeV [121]
    I^{A}_\mu = \bar c \gamma_\mu \gamma_5 c 0^+1^{++} \eta_c 0^+0^{-+} \langle 0 | I^{A}_\mu | \eta_c \rangle = {\rm i} p_\mu f_{\eta_c} f_{\eta_c} = 387 MeV [121]
    \chi_{c1}(1P) 0^+1^{++} \langle 0 | I^{A}_\mu | \chi_{c1} \rangle = m_{\chi_{c1}} f_{\chi_{c1}} \epsilon_\mu f_{\chi_{c1}} = 335 MeV [122]
    I^{T}_{\mu\nu} = \bar c \sigma_{\mu\nu} c 0^-1^{\pm-} J/\psi 0^-1^{–} \langle 0 | I^{T}_{\mu\nu} | J/\psi \rangle = {\rm i} f^T_{J/\psi} (p_\mu\epsilon_\nu - p_\nu\epsilon_\mu) f_{J/\psi}^T = 410 MeV [121]
    h_c(1P) 0^-1^{+-} \langle 0 | I^{T}_{\mu\nu} | h_c \rangle = {\rm i} f^T_{h_c} \epsilon_{\mu\nu\alpha\beta} \epsilon^\alpha p^\beta f_{h_c}^T = 235 MeV [121]
    O^{S} = \bar c q 0^{+} \bar D_0^{*} 0^{+} \langle 0 | O^{S} | \bar D_0^{*} \rangle = m_{D_0^{*}} f_{D_0^{*}} f_{D_0^{*}} = 410 MeV [123]
    O^{P} = \bar c i\gamma_5 q 0^{-} \bar D 0^{-} \langle 0 | O^{P} | \bar D \rangle = \lambda_D \lambda_D = {(f_D m_D^2) / {(m_c + m_d)} }
    O^{V}_\mu = \bar c \gamma_\mu q 1^{-} \bar D^{*} 1^{-} \langle0| O^{V}_\mu | \bar D^{*} \rangle = m_{D^*} f_{D^*} \epsilon_\mu f_{D^*} = 253 MeV [124]
    O^{A}_\mu = \bar c \gamma_\mu \gamma_5 q 1^{+} \bar D 0^{-} \langle 0 | O^{A}_\mu | \bar D \rangle = {\rm i} p_\mu f_{D} f_{D} = 211.9 MeV [2]
    \bar D_1 1^{+} \langle 0 | O^{A}_\mu | \bar D_1 \rangle = m_{D_1} f_{D_1} \epsilon_\mu f_{D_1} = 356 MeV [123]
    O^{T}_{\mu\nu} = \bar c \sigma_{\mu\nu} q 1^{\pm} \bar D^{*} 1^{-} \langle 0 | O^{T}_{\mu\nu} | \bar D^{*} \rangle = {\rm i} f_{D^*}^T (p_\mu\epsilon_\nu - p_\nu\epsilon_\mu) f_{D^*}^T \approx 220 MeV
    1^{+}
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    \begin{aligned}[b] N = N_1 - N_2 = \epsilon^{abc} (u_a^T \mathbb{C} d_b) \gamma_5 u_c - \epsilon^{abc} (u_a^T \mathbb{C} \gamma_5 d_b) u_c \, . \end{aligned}

    (86)

    This couples to a proton through

    \langle 0 | N | p \rangle = f_p u_p \, ,

    (87)

    with u_p as the Dirac spinor of the proton. The decay constant f_p has been calculated in Ref. [119] to be

    f_p = 0.011 {\rm\; GeV}^3 \, .

    (88)

    To study the decays of the \bar D^{(*)} \Sigma_c^{*} molecular states into charmed mesons and charmed baryons, we must use the \eta(x) and \xi(x) currents. These are constructed in Sec. II by combining charmed meson operators and charmed baryon fields. In the present study, we require the couplings of charmed meson operators to charmed meson states, which are also listed in Table 2. Furthermore, we require couplings of the charmed baryon fields J_{{\cal{B}}} defined in Eq. (16) to the ground-state charmed baryons {\cal{B}} = \Lambda_c/\Sigma_c .

    \langle 0 | J_{{\cal{B}}} | {\cal{B}} \rangle = f_{{\cal{B}}} u_{{\cal{B}}} \, .

    (89)

    Note that we do not investigate the decays of |\bar D^{(*)} \Sigma_c^{*}; J^P\rangle into the \bar D^{(*)} \Sigma_c^* final states in the present study because some J = 3/2 charmed baryon fields still remain unclear [76]. The decay constants f_{{\cal{B}}} have been calculated in Refs. [7779] to be

    \begin{aligned}[b] f_{\Lambda_c} = 0.015 {\rm\; GeV}^3 \, , \quad f_{\Sigma_c} = 0.036 {\rm\; GeV}^3 \, . \end{aligned}

    (90)

    These values are evaluated using the QCD sum rule method [81, 82] within heavy quark effective theory [8385], while the full QCD decay constant f_p for the proton has been given in Eq. (88). These two different schemes cause some, but not significant, theoretical uncertainties.

    In this subsection, we perform Fierz rearrangement separately for \eta_{4\cdots7} and \xi_{4\cdots7} . The obtained results are used later to study the strong decay properties of the \bar D \Sigma_c^{*} and \bar D^{*} \Sigma_c^{*} molecular states.

    First, however, we note again that Fierz rearrangement in Lorentz space is actually a matrix identity. It is valid if each quark field in the initial and final currents is at the same location, for example, we can apply Fierz rearrangement to transform a non-local current \eta = [\bar c(x) u(x)] \; [u(y) d(y) c(y)] into a combination of many non-local currents \theta = [\bar c(x) c(y)] \; [u(y) d(y) u(x)] with all the quark fields remaining at the same locations. Keeping this in mind, we omit the coordinates in this subsection.

    1   \eta \rightarrow \theta and \xi \rightarrow \theta

    Using the color rearrangement [76]

    \delta^{ab} \epsilon^{cde} = {1\over3}\; \delta^{ae} \epsilon^{bcd} - {1\over2}\; \lambda^{ae}_n \epsilon^{bcf} \lambda^{fd}_n + {1\over2}\; \lambda^{ae}_n \epsilon^{bdf} \lambda^{fc}_n \, ,

    (91)

    along with Fierz rearrangement to interchange the u_b and c_e quark fields, we can transform an η current into a combination of many θ currents.

    \begin{aligned}[b] \eta_4^\alpha \rightarrow & [\bar c_a \gamma_\mu c_a] \left( - {1\over32} g^{\alpha\mu} - {{\rm i}\over96} \sigma^{\alpha\mu} \right) N \\ & + \; [\bar c_a \gamma_\mu \gamma_5 c_a] \left( - {1\over32} g^{\alpha\mu} \gamma_5 - {{\rm i}\over96} \sigma^{\alpha\mu} \gamma_5 \right) N \\ & + \; [\bar c_a \sigma_{\mu\nu} c_a] \left( {{\rm i}\over48} g^{\alpha\mu}\gamma^\nu + {1\over96} \epsilon^{\alpha\mu\nu\rho} \gamma_\rho \gamma_5 \right) N \\ & + \; \cdots \, , \end{aligned}

    (92)

    \begin{aligned}[b] \eta_5 \rightarrow & + {1\over8} \; [\bar c_a c_a] \; \gamma_5 N + {1\over8} \; [\bar c_a \gamma_5 c_a] \; N \\ & + {1\over16} \; [\bar c_a \gamma_\mu c_a] \; \gamma^\mu \gamma_5 N - {1\over16} \; [\bar c_a \gamma_\mu \gamma_5 c_a] \; \gamma^\mu N \\ & + {1\over48} \; [\bar c_a \sigma_{\mu\nu} c_a] \; \sigma^{\mu\nu} \gamma_5 N + \cdots \, , \\[-10pt]\end{aligned}

    (93)

    \begin{aligned} [b] \eta_6^\alpha \rightarrow & [\bar c_a \gamma_\mu c_a] \left( {3\over32} g^{\alpha\mu} + {{\rm i}\over32} \sigma^{\alpha\mu} \right) N \\ & + \; [\bar c_a \gamma_\mu \gamma_5 c_a] \left( - {3\over32} g^{\alpha\mu} \gamma_5 - {{\rm i}\over32} \sigma^{\alpha\mu} \gamma_5 \right) N + \; \cdots \, , \end{aligned}

    (94)

    \begin{aligned}[b] \eta_7^{\alpha\beta}\rightarrow & \Big( {{\rm i}\over144} \sigma^{\alpha\rho}\epsilon^{\beta\mu\nu\rho} + {1\over72} g^{\alpha\mu}\sigma^{\beta\nu}\gamma_5 - {1\over144} g^{\alpha\beta}\sigma^{\mu\nu}\gamma_5 \Big) \\ & \times \; [\bar c_a \sigma_{\mu\nu} c_a] \; N + \cdots \, . \end{aligned}

    (95)

    In the above expressions, we keep all color-singlet-color-singlet meson-baryon terms depending on the J=1/2 light baryon fields but omit a) the color-octet-color-octet meson-baryon terms, such as [\lambda^{ae}_n \bar c_a c_e][\epsilon^{bcf}\lambda^{fd}_n u_b u_c d_d] , and b) terms depending on the J=3/2 light baryon fields.

    Similarly, we can use Eq. (91) along with Fierz rearrangement to interchange the d_b and c_e quark fields and transform a ξ current into a combination of many θ currents.

    \begin{aligned}[b] \sqrt2 \xi_4^\alpha \rightarrow & [\bar c_a \gamma_\mu c_a] \left( {1\over16} g^{\alpha\mu} + {{\rm i}\over48} \sigma^{\alpha\mu} \right) N \\ & + \; [\bar c_a \gamma_\mu \gamma_5 c_a] \left( {1\over16} g^{\alpha\mu} \gamma_5 + {{\rm i}\over48} \sigma^{\alpha\mu} \gamma_5 \right) N \\ & + \; [\bar c_a \sigma_{\mu\nu} c_a] \left( - {i\over24} g^{\alpha\mu}\gamma^\nu - {1\over48} \epsilon^{\alpha\mu\nu\rho} \gamma_\rho \gamma_5 \right) N \\ & + \; \cdots \, , \\[-5pt]\end{aligned}

    (96)

    \begin{aligned}[b] \sqrt2 \xi_5 \rightarrow & - {1\over4} \; [\bar c_a c_a] \; \gamma_5 N - {1\over4} \; [\bar c_a \gamma_5 c_a] \; N \\ & - {1\over8} \; [\bar c_a \gamma_\mu c_a] \; \gamma^\mu \gamma_5 N + {1\over8} \; [\bar c_a \gamma_\mu \gamma_5 c_a] \; \gamma^\mu N \\ & - {1\over24} \; [\bar c_a \sigma_{\mu\nu} c_a] \; \sigma^{\mu\nu} \gamma_5 N + \cdots \, , \end{aligned}

    (97)

    \begin{aligned}[b] \sqrt2 \xi_6^\alpha \rightarrow & [\bar c_a \gamma_\mu c_a] \left( - {3\over16} g^{\alpha\mu} - {{\rm i}\over16} \sigma^{\alpha\mu} \right) N \\ & + \; [\bar c_a \gamma_\mu \gamma_5 c_a] \left( {3\over16} g^{\alpha\mu} \gamma_5 + {{\rm i}\over16} \sigma^{\alpha\mu} \gamma_5 \right) N \\ & + \; \cdots \, , \end{aligned}

    (98)

    \begin{aligned}[b] \sqrt2 \xi_7^{\alpha\beta} \rightarrow & \Big( - {{\rm i}\over72} \sigma^{\alpha\rho}\epsilon^{\beta\mu\nu\rho} - {1\over36} g^{\alpha\mu}\sigma^{\beta\nu}\gamma_5 \\ & + {1\over72} g^{\alpha\beta}\sigma^{\mu\nu}\gamma_5 \Big) \; [\bar c_a \sigma_{\mu\nu} c_a] \; N + \cdots \, . \end{aligned}

    (99)
    2   \eta \rightarrow \eta and \eta \rightarrow \xi

    Using the color rearrangement

    \delta^{ab} \epsilon^{cde} = {1\over3}\; \delta^{ac} \epsilon^{bde} - {1\over2}\; \lambda^{ac}_n \epsilon^{bdf} \lambda^{fe}_n + {1\over2}\; \lambda^{ac}_n \epsilon^{bef} \lambda^{fd}_n \, ,

    (100)

    along with Fierz rearrangement to interchange the u_b and u_c quark fields, we can transform an η current into a combination of many η currents.

    Using another color rearrangement

    \begin{aligned}[b] \delta^{ab} \epsilon^{cde} =& {1\over3}\; \delta^{ad} \epsilon^{cbe} + {1\over2}\; \lambda^{ad}_n \epsilon^{bcf} \lambda^{fe}_n \\&- {1\over2}\; \lambda^{ad}_n \epsilon^{bef} \lambda^{fc}_n \, , \end{aligned}

    (101)

    along with Fierz rearrangement to interchange the u_b and d_d quark fields, we can transform an η current into a combination of many ξ currents.

    Overall, we obtain

    \begin{aligned}[b] \eta_4^\alpha \rightarrow & \left( {1\over16}g^{\alpha\mu} + {{\rm i}\over48}\sigma^{\alpha\mu} \right) \; [\bar c_a \gamma_\mu u_a] \; \Lambda_c^+ \\ &+ \left( {{\rm i}\over384}\sigma^{\alpha\sigma} \epsilon^{\mu\nu\rho\sigma} - {1\over128}\epsilon^{\alpha\mu\nu\rho} \right) [\bar c_a \sigma_{\mu\nu} u_a] \gamma_\rho \gamma_5 \Sigma_c^+ \\ &+ \left( {{\rm i}\sqrt2\over384}\sigma^{\alpha\sigma} \epsilon^{\mu\nu\rho\sigma} - {\sqrt2\over128}\epsilon^{\alpha\mu\nu\rho} \right) \\ & \times \; [\bar c_a \sigma_{\mu\nu} d_a] \; \gamma_\rho \gamma_5 \Sigma_c^{++} + \cdots \, , \end{aligned}

    (102)

    \begin{aligned}[b] \eta_5 \rightarrow & - {1\over4} \; [\bar c_a \gamma_5 u_a] \; \Lambda_c^+ - {1\over48} \; [\bar c_a \sigma_{\mu\nu} u_a] \; \sigma^{\mu\nu}\gamma_5 \Lambda_c^+ \\ & - {1\over32} \; [\bar c_a \gamma_\mu u_a] \; \gamma^\mu \gamma_5 \Sigma_c^+ + {1\over32} \; [\bar c_a \gamma_\mu \gamma_5 u_a] \; \gamma^\mu \Sigma_c^+ \\ & - {\sqrt2\over32} [\bar c_a \gamma_\mu d_a] \gamma^\mu \gamma_5 \Sigma_c^{++} + {\sqrt2\over32} [\bar c_a \gamma_\mu \gamma_5 d_a] \gamma^\mu \Sigma_c^{++} \\ & + \; \cdots \, , \end{aligned}

    (103)

    \begin{aligned}[b] \eta_6^\alpha \rightarrow & \left( {{\rm i}\over16}g^{\alpha\mu}\gamma^\nu + {1\over32}\epsilon^{\alpha\mu\nu\rho}\gamma_\rho\gamma_5 \right) \; [\bar c_a \sigma_{\mu\nu} u_a] \; \Lambda_c^+ \\ &+ \left( {1\over96}g^{\alpha\mu}\gamma^\nu\gamma_5 + {1\over96}g^{\alpha\nu}\gamma^\mu\gamma_5 - {1\over192}g^{\mu\nu}\gamma^\alpha\gamma_5 \right) \\ & \times \; [\bar c_a \gamma_\mu u_a] \; \gamma_\nu \gamma_5 \Sigma_c^+ \\ &+ \left( {1\over64}g^{\alpha\mu}\gamma^\nu - {1\over64}g^{\alpha\nu}\gamma^\mu - {{\rm i}\over64}\epsilon^{\alpha \mu \nu \rho}\gamma_\rho\gamma_5 \right) \\ & \times \; [\bar c_a \gamma_\mu \gamma_5 u_a] \; \gamma_\nu \gamma_5 \Sigma_c^+ \\ &+ \left( {\sqrt2\over96}g^{\alpha\mu}\gamma^\nu\gamma_5 + {\sqrt2\over96}g^{\alpha\nu}\gamma^\mu\gamma_5 - {\sqrt2\over192}g^{\mu\nu}\gamma^\alpha\gamma_5 \right) \\ & \times \; [\bar c_a \gamma_\mu d_a] \; \gamma_\nu \gamma_5 \Sigma_c^{++} \\ &+ \left( {\sqrt2\over64}g^{\alpha\mu}\gamma^\nu - {\sqrt2\over64}g^{\alpha\nu}\gamma^\mu - {{\rm i}\sqrt2\over64}\epsilon^{\alpha \mu \nu \rho}\gamma_\rho\gamma_5 \right) \\ &\times \; [\bar c_a \gamma_\mu \gamma_5 d_a] \; \gamma_\nu \gamma_5 \Sigma_c^{++} + \cdots \, , \end{aligned}

    (104)

    \begin{aligned}[b] \eta_7^{\alpha\beta} \rightarrow & \Big( {1\over36}g^{\alpha\mu}g^{\beta\nu} - {1\over144}g^{\alpha\beta}g^{\mu\nu} + {{\rm i}\over144}g^{\alpha\mu}\sigma^{\beta\nu} \\ & + {{\rm i}\over144}g^{\alpha\nu}\sigma^{\beta\mu} \Big) \; [\bar c_a \gamma_\mu u_a] \; \gamma_\nu \gamma_5 \Sigma_c^+ \\ &+ \Big( {\sqrt2\over36}g^{\alpha\mu}g^{\beta\nu} - {\sqrt2\over144}g^{\alpha\beta}g^{\mu\nu} + {{\rm i}\sqrt2\over144}g^{\alpha\mu}\sigma^{\beta\nu} \\ &+ {{\rm i}\sqrt2\over144}g^{\alpha\nu}\sigma^{\beta\mu} \Big) \; [\bar c_a \gamma_\mu d_a] \; \gamma_\nu \gamma_5 \Sigma_c^{++} + \cdots \, . \end{aligned}

    (105)

    In the above expressions, we keep all color-singlet-color-singlet meson-baryon terms depending on the J^P=1/2^+ charmed baryon fields, that is, J_{\Lambda_c^+} and J_{\Sigma_c^{+/++}} defined in Eqs. (16). However, we omit a) the color-octet-color-octet meson-baryon terms and b) terms depending on the J=3/2 charmed baryon fields.

    3   \xi \rightarrow \eta

    Using Eqs. (100) and (101) along with Fierz rearrangement in Lorentz space, we can transform a ξ current into a combination of many η currents (but without ξ currents).

    \begin{aligned}[b] \sqrt2 \xi_4^\alpha \rightarrow & \left( - {1\over8}g^{\alpha\mu} - {{\rm i}\over24}\sigma^{\alpha\mu} \right) \; [\bar c_a \gamma_\mu u_a] \; \Lambda_c^+ \\ &+ \left( {{\rm i}\over192}\sigma^{\alpha\sigma} \epsilon^{\mu\nu\rho\sigma} - {1\over64}\epsilon^{\alpha\mu\nu\rho} \right) \\ & \times \; [\bar c_a \sigma_{\mu\nu} u_a] \; \gamma_\rho \gamma_5 \Sigma_c^+ + \cdots \, , \end{aligned}

    (106)

    \begin{aligned}[b] \sqrt2 \xi_5 \rightarrow & + {1\over2} \; [\bar c_a \gamma_5 u_a] \; \Lambda_c^+ + {1\over24} \; [\bar c_a \sigma_{\mu\nu} u_a] \; \sigma^{\mu\nu}\gamma_5 \Lambda_c^+ \\ & - {1\over16} [\bar c_a \gamma_\mu u_a] \gamma^\mu \gamma_5 \Sigma_c^+ + {1\over16} [\bar c_a \gamma_\mu \gamma_5 u_a] \gamma^\mu \Sigma_c^+ \\ & + \; \cdots \, , \\[-10pt]\end{aligned}

    (107)

    \begin{aligned}[b] \sqrt2 \xi_6^\alpha \rightarrow & \left( - {{\rm i}\over8}g^{\alpha\mu}\gamma^\nu - {1\over16}\epsilon^{\alpha\mu\nu\rho}\gamma_\rho\gamma_5 \right) \; [\bar c_a \sigma_{\mu\nu} u_a] \; \Lambda_c^+ \\ &+ \left( {1\over48}g^{\alpha\mu}\gamma^\nu\gamma_5 + {1\over48}g^{\alpha\nu}\gamma^\mu\gamma_5 - {1\over96}g^{\mu\nu}\gamma^\alpha\gamma_5 \right) \\ & \times \; [\bar c_a \gamma_\mu u_a] \; \gamma_\nu \gamma_5 \Sigma_c^+ \\ &+ \left( {1\over32}g^{\alpha\mu}\gamma^\nu - {1\over32}g^{\alpha\nu}\gamma^\mu - {{\rm i}\over32}\epsilon^{\alpha \mu \nu \rho}\gamma_\rho\gamma_5 \right) \\ & \times \; [\bar c_a \gamma_\mu \gamma_5 u_a] \; \gamma_\nu \gamma_5 \Sigma_c^+ + \cdots \, , \end{aligned}

    (108)

    \begin{aligned}[b] \sqrt2 \xi_7^{\alpha\beta} \rightarrow & \Big( {1\over18}g^{\alpha\mu}g^{\beta\nu} - {1\over72}g^{\alpha\beta}g^{\mu\nu} + {{\rm i}\over72}g^{\alpha\mu}\sigma^{\beta\nu} \\ & + {{\rm i}\over72}g^{\alpha\nu}\sigma^{\beta\mu} \Big) \; [\bar c_a \gamma_\mu u_a] \; \gamma_\nu \gamma_5 \Sigma_c^+ + \cdots \, . \end{aligned}

    (109)

    Based on the Fierz rearrangements derived in the previous subsection, we now study the strong decay properties of the \bar D^{(*)0} \Sigma_c^{*+} and D^{(*)-} \Sigma_c^{*++} molecular states. As an example, we first investigate |\bar D^0 \Sigma_c^{*+}; 3/2^- \rangle through the \eta_4 current and Fierz rearrangements given in Eqs. (92) and (102). Others are similarly investigated. The obtained results are combined in Sec. V.D to further study the \bar D^{(*)} \Sigma_c^* molecular states of I=1/2 .

    1   \eta_4 \rightarrow \theta / \eta / \xi

    As an example, we investigate |\bar D^0 \Sigma_c^{*+}; 3/2^- \rangle through the \eta_4 current and Fierz rearrangements given in Eqs. (97) and (107).

    First, we study Eq. (92). As depicted in Fig. 5(a), when the \bar c_a and c_e quarks meet and the other three quarks meet simultaneously, |\bar D^0 \Sigma_c^{*+}; 3/2^- \rangle can decay into one charmonium meson and one light baryon.

    Figure 5

    Figure 5.  (color online) Fall-apart decays of the \bar D^{(*)0} \Sigma_c^{(*)+} molecular states investigated using the η currents. There are three possible decay processes: a) \eta \rightarrow \theta, b) \eta \rightarrow \eta, and c) \eta \rightarrow \xi. Their probabilities are the same (33%) if only considering the color degree of freedom. Taken from Ref. [76].

    \begin{aligned}[b] &\;\; \left[\delta^{ab} \bar c_a u_b\right] \; \left[\epsilon^{cde} u_c d_d c_e\right] \\ \underline{\underline {{\rm{color}}}} &\;\; {1\over3}\delta^{ae} \epsilon^{bcd} \; \bar c_au_b \; u_c d_d c_e + \cdots \\ \underline{\underline {{\rm{Fierz}}}} &\;\; {1\over3} \; \left[\delta^{ae}\bar c_a c_e\right] \; \left[\epsilon^{bcd} u_c d_d u_b\right] + \cdots . \end{aligned}

    (110)

    In particular, we must apply Fierz rearrangement in the first and third steps to interchange both the color and Dirac indices of the u_b and c_e quark fields.

    The above decay process can be described by the Fierz rearrangement given in Eq. (92), from which we extract the following two decay channels that are kinematically allowed:

    1. The decay of |\bar D^0 \Sigma_c^{*+}; 3/2^- \rangle into \eta_c p is contributed by [\bar c_a \gamma_\mu \gamma_5 c_a]N .

    \begin{aligned}[b] & \langle \bar D^0 \Sigma_c^{*+}; 3/2^-(q) \; |\; \eta_c(q_1)\; p(q_2) \rangle \\ \approx& {a_4}\; {\rm i} f_{\eta_c} f_p q_1^\mu \; \bar u^\alpha \left( - {1\over32} g_{\alpha\mu} \gamma_5 - {{\rm i}\over96} \sigma_{\alpha\mu} \gamma_5 \right) u_p \, , \end{aligned}

    (111)

    where u_\alpha and u_p are spinors of |\bar D^0 \Sigma_c^{*+}; 3/2^- \rangle and the proton, respectively. a_4 is an overall factor related to the coupling of \eta_4 to |\bar D^0 \Sigma_c^{*+}; 3/2^- \rangle and the dynamical process of Fig. 5(a).

    2. The decay of |\bar D^0 \Sigma_c^{*+}; 3/2^- \rangle into J/\psi p is contributed by both [\bar c_a \gamma_\mu c_a]N and [\bar c_a \sigma_{\mu\nu} c_a]N .

    \begin{aligned}[b] & \langle \bar D^0 \Sigma_c^{*+}; 3/2^-(q) | J/\psi(q_1,\epsilon_1)\; p(q_2) \rangle \\ \approx& {a_4}\; m_{J/\psi} f_{J/\psi} f_p \epsilon_1^\mu \; \bar u^\alpha \left( - {1\over32} g_{\alpha\mu} - {{\rm i}\over96} \sigma_{\alpha\mu} \right) u_p \\ &+ {a_4}\; {\rm i}f^T_{J/\psi} f_p \; \left(q_1^\mu \epsilon_1^\nu - q_1^\nu \epsilon_1^\mu \right) \\ &\times \bar u^\alpha \left( {{\rm i}\over48} g_{\alpha\mu}\gamma_\nu + {1\over96} \epsilon_{\alpha\mu\nu\rho} \gamma^\rho \gamma_5 \right) u_p \, . \end{aligned}

    (112)

    Subsequently, we study Eq. (102). As depicted in Fig. 5(b), when the \bar c_a and u_c quarks meet and the other three quarks meet simultaneously, |\bar D^0 \Sigma_c^{*+}; 3/2^- \rangle can decay into one charmed meson and one charmed baryon. Similarly, we can study the decay process depicted in Fig. 5(c). These two processes can be described by the Fierz rearrangement given in Eq. (102), from which we extract only one decay channel that is kinematically allowed:

    3. The decay of |\bar D^0 \Sigma_c^{*+}; 3/2^- \rangle into \bar D^{*0} \Lambda_c^+ is contributed by [\bar c_a \gamma_\mu u_a]\Lambda_c^+ :

    \begin{aligned}[b] & \langle \bar D^0 \Sigma_c^{*+}; 3/2^-(q) \; |\; \bar D^{*0}(q_1,\epsilon_1)\; \Lambda_c^+(q_2) \rangle \\ \approx& {b_4}\; m_{D^*} f_{D^*} f_{\Lambda_c} \epsilon_1^\mu \; \bar u^\alpha \left( {1\over16}g_{\alpha\mu} + {{\rm i}\over48}\sigma_{\alpha\mu} \right) u_{\Lambda_c} \, , \end{aligned}

    (113)

    where u_{\Lambda_c} is the Dirac spinor of \Lambda_c^+ . b_4 is an overall factor related to the coupling of \eta_4 to |\bar D^0 \Sigma_c^{*+}; 3/2^- \rangle and the dynamical processes of Fig. 5(b, c).

    Assuming the mass of |\bar D^0 \Sigma_c^{*+}; 3/2^- \rangle to be approximately M_{D} + M_{\Sigma_c^*} \approx 4385 MeV, we summarize the above decay amplitudes to obtain the following partial decay widths:

    \begin{aligned}[b] \Gamma(|\bar D^0 \Sigma_c^{*+}; 3/2^- \rangle \to \eta_c p ) =& a_4^2 \; 42 \; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^0 \Sigma_c^{*+}; 3/2^- \rangle \to J/\psi p ) =& a_4^2 \; 60 \; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^0 \Sigma_c^{*+}; 3/2^- \rangle \to \bar D^{*0} \Lambda_c^+ ) =& b_4^2 \; 1.5 \times 10^{4}\; {\rm{GeV}}^7 \, . \end{aligned}

    (114)

    There are two different terms, A \equiv [\bar c_a \gamma_\mu c_a]N and B \equiv [\bar c_a \sigma_{\mu\nu} c_a]N , both of which can contribute to the decay of |\bar D^0 \Sigma_c^{*+}; 3/2^- \rangle into J/\psi p . Their individual contributions are

    \begin{aligned}[b] \Gamma(|\bar D^0 \Sigma_c^{*+}; 3/2^- \rangle \to J/\psi p )\big|_A =& a_4^2 \; 1.0 \times 10^{4}\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^0 \Sigma_c^{*+}; 3/2^- \rangle \to J/\psi p )\big|_B =& a_4^2 \; 1.1 \times 10^{4}\; {\rm{GeV}}^7 \, . \end{aligned}

    (115)

    Hence, their contributions are at the same level but almost cancel each other out, suggesting that their interference is important. However, the phase angle between them, that is, the phase angle between the two coupling constants f_{J/\psi} and f_{J/\psi}^T , cannot be well determined in the present study. We investigate its relevant (theoretical) uncertainty in Appendix B.

    2   \xi_4 \rightarrow \theta / \eta

    To study |D^{-} \Sigma_c^{*++}; 3/2^- \rangle , we use the \xi_4 current and Fierz rearrangements given in Eqs. (96) and (106). Assuming its mass to be the same as that of |\bar D^{0} \Sigma_c^{*+}; 3/2^- \rangle , we obtain the following partial decay widths:

    \begin{aligned}[b] \Gamma(|D^- \Sigma_c^{*++}; 3/2^- \rangle \to \eta_c p ) =& a_4^2 \; 84 \; {\rm{GeV}}^7 \, , \\ \Gamma(|D^- \Sigma_c^{*++}; 3/2^- \rangle \to J/\psi p ) =& a_4^2 \; 120 \; {\rm{GeV}}^7 \, , \\ \Gamma(|D^- \Sigma_c^{*++}; 3/2^- \rangle \to \bar D^{*0} \Lambda_c^+ ) =& b_4^2 \; 3.0 \times 10^{4}\; {\rm{GeV}}^7 \, . \end{aligned}

    (116)

    Here, we use the same overall factors a_4 and b_4 as those for the \eta_4 current.

    3   \eta_5 \rightarrow \theta / \eta / \xi

    To study |\bar D^{*0} \Sigma_c^{*+}; 1/2^- \rangle , we use the \eta_5 current and Fierz rearrangements given in Eqs. (93) and (103). Assuming its mass to be approximately M_{D^*} + M_{\Sigma_c^*} \approx 4527 MeV, we obtain the following partial decay widths:

    \begin{aligned}[b] \Gamma(|\bar D^{*0} \Sigma_c^{*+}; 1/2^- \rangle \to \eta_c p ) =& a_5^2 \; 3.3 \times 10^{5} \; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*0} \Sigma_c^{*+}; 1/2^- \rangle \to J/\psi p ) =& a_5^2 \; 1.0 \times 10^{4} \; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*0} \Sigma_c^{*+}; 1/2^- \rangle \to \chi_{c0} p ) =& a_5^2 \; 3.2 \times 10^{3} \; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*0} \Sigma_c^{*+}; 1/2^- \rangle \to \chi_{c1} p ) =& a_5^2 \; 1.1 \times 10^{3} \; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*0} \Sigma_c^{*+}; 1/2^- \rangle \to h_{c} p ) =& a_5^2 \; 220 \; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*0} \Sigma_c^{*+}; 1/2^- \rangle \to \bar D^{0} \Lambda_c^+ ) =& b_5^2 \; 3.5 \times 10^{5}\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*0} \Sigma_c^{*+}; 1/2^- \rangle \to \bar D^{*0} \Lambda_c^+ ) =& b_5^2 \; 1.6 \times 10^{4}\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*0} \Sigma_c^{*+}; 1/2^- \rangle \to \bar D^{0} \Sigma_c^+ )=& b_5^2 \; 1.4 \times 10^{4}\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*0} \Sigma_c^{*+}; 1/2^- \rangle \to D^- \Sigma_c^{++} ) =& b_5^2 \; 2.9 \times 10^{4}\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*0} \Sigma_c^{*+}; 1/2^- \rangle \to \bar D^{*0} \Sigma_c^+ ) =& b_5^2 \; 3.3 \times 10^{4}\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*0} \Sigma_c^{*+}; 1/2^- \rangle \to D^{*-} \Sigma_c^{++} ) =& b_5^2 \; 6.6 \times 10^{4}\; {\rm{GeV}}^7 \, , \end{aligned}

    (117)

    where a_5 and b_5 are two overall factors.

    4   \xi_5 \rightarrow \theta / \eta

    To study |D^{*-} \Sigma_c^{*++}; 1/2^- \rangle , we use the \xi_5 current and the Fierz rearrangements given in Eqs. (97) and (107). Assuming its mass to be the same as that of |\bar D^{*0} \Sigma_c^{*+}; 1/2^- \rangle , we obtain the following partial decay widths:

    \begin{aligned}[b] \Gamma(|D^{*-} \Sigma_c^{*++}; 1/2^- \rangle \to \eta_c p ) =& a_5^2 \; 6.5 \times 10^{5} \; {\rm{GeV}}^7 \, , \\ \Gamma(|D^{*-} \Sigma_c^{*++}; 1/2^- \rangle \to J/\psi p ) =& a_5^2 \; 2.1 \times 10^{4} \; {\rm{GeV}}^7 \, , \\ \Gamma(|D^{*-} \Sigma_c^{*++}; 1/2^- \rangle \to \chi_{c0} p ) =& a_5^2 \; 6.4 \times 10^{3} \; {\rm{GeV}}^7 \, , \\ \Gamma(|D^{*-} \Sigma_c^{*++}; 1/2^- \rangle \to \chi_{c1} p ) =& a_5^2 \; 2.1 \times 10^{3} \; {\rm{GeV}}^7 \, , \\ \Gamma(|D^{*-} \Sigma_c^{*++}; 1/2^- \rangle \to h_{c} p ) =& a_5^2 \; 450 \; {\rm{GeV}}^7 \, , \\ \Gamma(|D^{*-} \Sigma_c^{*++}; 1/2^- \rangle \to \bar D^{0} \Lambda_c^+ ) =& b_5^2 \; 7.0 \times 10^{5}\; {\rm{GeV}}^7 \, , \\ \Gamma(|D^{*-} \Sigma_c^{*++}; 1/2^- \rangle \to \bar D^{*0} \Lambda_c^+ ) =& b_5^2 \; 3.1 \times 10^{4}\; {\rm{GeV}}^7 \, , \\ \Gamma(|D^{*-} \Sigma_c^{*++}; 1/2^- \rangle \to \bar D^{0} \Sigma_c^+ ) =& b_5^2 \; 2.9 \times 10^{4}\; {\rm{GeV}}^7 \, , \\ \Gamma(|D^{*-} \Sigma_c^{*++}; 1/2^- \rangle \to \bar D^{*0} \Sigma_c^+ ) =& b_5^2 \; 6.6 \times 10^{4}\; {\rm{GeV}}^7 \, . \end{aligned}

    (118)
    5   \eta_6 \rightarrow \theta / \eta / \xi

    To study |\bar D^{*0} \Sigma_c^{*+}; 3/2^- \rangle , we use the \eta_6 current and Fierz rearrangements given in Eqs. (94) and (104). Assuming its mass to be the same as that of |\bar D^{*0} \Sigma_c^{*+}; 1/2^- \rangle , we obtain the following partial decay widths:

    \begin{aligned}[b] \Gamma(|\bar D^{*0} \Sigma_c^{*+}; 3/2^- \rangle \to \eta_c p ) =& a_6^2 \; 750 \; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*0} \Sigma_c^{*+}; 3/2^- \rangle \to J/\psi p ) =& a_6^2 \; 1.2 \times 10^{5} \; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*0} \Sigma_c^{*+}; 3/2^- \rangle \to \chi_{c0} p ) =& a_6^2 \; 960 \; {\rm{GeV}}^7 \, ,\\ \Gamma(|\bar D^{*0} \Sigma_c^{*+}; 3/2^- \rangle \to \bar D^{*0} \Lambda_c^+ )=& b_6^2 \; 4.5 \times 10^{4}\; {\rm{GeV}}^7 \, , \\ \end{aligned}

    \begin{aligned}[b] \Gamma(|\bar D^{*0} \Sigma_c^{*+}; 3/2^- \rangle \to \bar D^{0} \Sigma_c^+ ) =& b_6^2 \; 36\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*0} \Sigma_c^{*+}; 3/2^- \rangle \to D^- \Sigma_c^{++} ) =& b_6^2 \; 71\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*0} \Sigma_c^{*+}; 3/2^- \rangle \to \bar D^{*0} \Sigma_c^+ ) =& b_6^2 \; 4.3 \times 10^{4}\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*0} \Sigma_c^{*+}; 3/2^- \rangle \to D^{*-} \Sigma_c^{++} ) =& b_6^2 \; 8.7 \times 10^{4}\; {\rm{GeV}}^7 \, , \end{aligned}

    (119)

    where a_6 and b_6 are two overall factors.

    6   \xi_6 \rightarrow \theta / \eta

    To study |D^{*-} \Sigma_c^{*++}; 3/2^- \rangle , we use the \xi_6 current and Fierz rearrangements given in Eqs. (98) and (108). Assuming its mass to be the same as that of |\bar D^{*0} \Sigma_c^{*+}; 1/2^- \rangle , we obtain the following partial decay widths:

    \begin{aligned}[b] \Gamma(|D^{*-} \Sigma_c^{*++}; 3/2^- \rangle \to \eta_c p ) =& a_6^2 \; 1.5 \times 10^{3} \; {\rm{GeV}}^7 \, , \\ \Gamma(|D^{*-} \Sigma_c^{*++}; 3/2^- \rangle \to J/\psi p ) =& a_6^2 \; 2.3 \times 10^{5} \; {\rm{GeV}}^7 \, , \\ \Gamma(|D^{*-} \Sigma_c^{*++}; 3/2^- \rangle \to \chi_{c0} p ) =& a_6^2 \; 1.9 \times 10^{3} \; {\rm{GeV}}^7 \, , \\ \Gamma(|D^{*-} \Sigma_c^{*++}; 3/2^- \rangle \to \bar D^{*0} \Lambda_c^+ ) =& b_6^2 \; 9.1 \times 10^{4}\; {\rm{GeV}}^7 \, , \\ \Gamma(|D^{*-} \Sigma_c^{*++}; 3/2^- \rangle \to \bar D^{0} \Sigma_c^+ ) =& b_6^2 \; 71\; {\rm{GeV}}^7 \, , \\ \Gamma(|D^{*-} \Sigma_c^{*++}; 3/2^- \rangle \to \bar D^{*0} \Sigma_c^+ ) =& b_6^2 \; 8.7 \times 10^{4}\; {\rm{GeV}}^7 \, . \end{aligned}

    (120)
    7   \eta_7 \rightarrow \theta / \eta / \xi and \xi_7 \rightarrow \theta / \eta

    To study |\bar D^{*0} \Sigma_c^{*+}; 5/2^- \rangle , we use the \eta_7 current and Fierz rearrangements given in Eqs. (95) and (105); however, we do not obtain any non-zero decay channels. This state probably mainly decays into spin-1 mesons and spin-3/2 baryons, such as J/\psi N^* and D^* \Sigma_c^* . However, these final states are not investigated in the present study. The same results are obtained for |D^{*-} \Sigma_c^{*++}; 5/2^- \rangle .

    In this subsection, we collect the results calculated in the previous subsection to further study the decay properties of the \bar D^{(*)} \Sigma_c^* molecular states with I=1/2 .

    Combining the results of Sec. V.C.1 and Sec. V.C.2, we obtain the following partial decay widths for |\bar D \Sigma_c^{*}; 3/2^- \rangle of I=1/2 :

    \begin{aligned}[b] \Gamma(|\bar D \Sigma_c^{*}; 3/2^- \rangle \to \eta_c p ) =& a_4^2 \; 130 \; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D \Sigma_c^{*}; 3/2^- \rangle \to J/\psi p ) =& a_4^2 \; 180 \; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D \Sigma_c^{*}; 3/2^- \rangle \to \bar D^{*0} \Lambda_c^+ ) =& b_4^2 \; 4.5 \times 10^{4}\; {\rm{GeV}}^7 \, . \end{aligned}

    (121)

    Combining the results of Sec. V.C.3 and Sec. V.C.4, we obtain the following partial decay widths for |\bar D^* \Sigma_c^{*}; 1/2^- \rangle of I=1/2 :

    \begin{aligned}[b] \Gamma(|\bar D^{*} \Sigma_c^{*}; 1/2^- \rangle \to \eta_c p ) =a_5^2 \; 9.8 \times 10^{5} \; {\rm{GeV}}^7 \, , \end{aligned}

    \begin{aligned}[b] \Gamma(|\bar D^{*} \Sigma_c^{*}; 1/2^- \rangle \to J/\psi p ) =& a_5^2 \; 3.1 \times 10^{4} \; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c^{*}; 1/2^- \rangle \to \chi_{c0} p ) =& a_5^2 \; 9.5 \times 10^{3} \; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c^{*}; 1/2^- \rangle \to \chi_{c1} p ) =& a_5^2 \; 3.2 \times 10^{3} \; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c^{*}; 1/2^- \rangle \to h_{c} p ) =& a_5^2 \; 670 \; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c^{*}; 1/2^- \rangle \to \bar D^{0} \Lambda_c^+ ) =& b_5^2 \; 1.1 \times 10^{6}\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c^{*}; 1/2^- \rangle \to \bar D^{*0} \Lambda_c^+ ) =& b_5^2 \; 4.7 \times 10^{4}\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c^{*}; 1/2^- \rangle \to \bar D^{0} \Sigma_c^+ ) =& b_5^2 \; 4.8 \times 10^{3}\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c^{*}; 1/2^- \rangle \to D^- \Sigma_c^{++} ) =& b_5^2 \; 9.6 \times 10^{3}\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c^{*}; 1/2^- \rangle \to \bar D^{*0} \Sigma_c^+ ) =& b_5^2 \; 1.1 \times 10^{4}\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c^{*}; 1/2^- \rangle \to D^{*-} \Sigma_c^{++} ) =& b_5^2 \; 2.2 \times 10^{4}\; {\rm{GeV}}^7 \, . \end{aligned}

    (122)

    Combining the results of Sec. V.C.5 and Sec. V.C.6, we obtain the following partial decay widths for |\bar D^* \Sigma_c^{*}; 3/2^- \rangle of I=1/2 :

    \begin{aligned}[b] \Gamma(|\bar D^{*} \Sigma_c^{*}; 3/2^- \rangle \to \eta_c p ) =& a_6^2 \; 2.2 \times 10^{3} \; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c^{*}; 3/2^- \rangle \to J/\psi p ) =& a_6^2 \; 3.5 \times 10^{5} \; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c^{*}; 3/2^- \rangle \to \chi_{c0} p ) =& a_6^2 \; 2.9 \times 10^{3} \; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c^{*}; 3/2^- \rangle \to \bar D^{*0} \Lambda_c^+ ) =& b_6^2 \; 1.4 \times 10^{5}\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c^{*}; 3/2^- \rangle \to \bar D^{0} \Sigma_c^+ ) =& b_6^2 \; 12\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c^{*}; 3/2^- \rangle \to D^- \Sigma_c^{++} ) =& b_6^2 \; 24\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c^{*}; 3/2^- \rangle \to \bar D^{*0} \Sigma_c^+ ) =& b_6^2 \; 1.4 \times 10^{4}\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c^{*}; 3/2^- \rangle \to D^{*-} \Sigma_c^{++} ) =& b_6^2 \; 2.9 \times 10^{4}\; {\rm{GeV}}^7 \, . \end{aligned}

    (123)

    We do not obtain any non-zero decay channels for |\bar D^* \Sigma_c^{*}; 5/2^- \rangle of I=1/2 . This state probably mainly decays into spin-1 mesons and spin-3/2 baryons, such as J/\psi N^* and \bar D^* \Sigma_c^* . However, these final states are not investigated in the present study.

    The decay properties of the \bar D^{(*)} \Sigma_c molecular states havebeen investigated in Ref. [76], including |\bar D \Sigma_c; 1/2^- \rangle , |\bar D^{*} \Sigma_c; 1/2^- \rangle , and |\bar D^{*} \Sigma_c; 3/2^- \rangle . There, we used them to explain P_c(4312)^+ , P_c(4440)^+ , and P_c(4457)^+ , respectively. However, we find that P_c(4440)^+ and P_c(4457)^+ can be better interpreted in our framework as |\bar D^{*} \Sigma_c; 3/2^- \rangle and |\bar D^{*} \Sigma_c; 1/2^- \rangle , respectively/inversely.

    Accordingly, we assume the masses of |\bar D \Sigma_c; 1/2^- \rangle , |\bar D^{*} \Sigma_c; 1/2^- \rangle , and |\bar D^{*} \Sigma_c; 3/2^- \rangle to be M_{P_c(4312)^+} = 4311.9 MeV, M_{P_c(4457)^+} = 4457.3 MeV, and M_{P_c(4440)^+} = 4440.3 MeV, respectively. Recalculations are performed, and we summarize the results here. Note that a) some errors were detected in the results of Ref. [76] when calculating \Gamma(|\bar D^* \Sigma_c; 1/2^- \rangle \to J/\psi p) , and b) different notations are used here for the overall factors.

    For |\bar D \Sigma_c; 1/2^- \rangle of I=1/2 , we find

    \begin{aligned}[b] \Gamma(|\bar D \Sigma_c; 1/2^- \rangle \to \eta_c p ) =a_1^2 \; 3.2 \times 10^{5}\; {\rm{GeV}}^7 \, , \end{aligned}

    \begin{aligned}[b] \Gamma(|\bar D \Sigma_c; 1/2^- \rangle \to J/\psi p ) =& a_1^2 \; 8.5 \times 10^{4}\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D \Sigma_c; 1/2^- \rangle \to \bar D^{*0} \Lambda_c^+ ) =& b_1^2 \; 5.9 \times 10^{4}\; {\rm{GeV}}^7 \, . \end{aligned}

    (124)

    For |\bar D^{*} \Sigma_c; 1/2^- \rangle of I=1/2 , we find

    \begin{aligned}[b] \Gamma(|\bar D^{*} \Sigma_c; 1/2^- \rangle \to \eta_c p ) =& a_2^2 \; 1.8 \times 10^{5}\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c; 1/2^- \rangle \to J/\psi p ) =& a_2^2 \; 5.1 \times 10^{5}\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c; 1/2^- \rangle \to \chi_{c0} p ) =& a_2^2 \; 8.0 \times 10^{3}\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c; 1/2^- \rangle \to \chi_{c1} p ) =& a_2^2 \; 200\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c; 1/2^- \rangle \to \bar D^{0} \Lambda_c^+ ) =& b_2^2 \; 1.7 \times 10^{6}\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c; 1/2^- \rangle \to \bar D^{*0} \Lambda_c^+ ) =& b_2^2 \; 6.0 \times 10^{5}\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c; 1/2^- \rangle \to \bar D^{0} \Sigma_c^+ ) =& b_2^2 \; 5.9 \times 10^{4}\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c; 1/2^- \rangle \to D^- \Sigma_c^{++} ) =& b_2^2 \; 1.2 \times 10^{5}\; {\rm{GeV}}^7 \, . \end{aligned}

    (125)

    For |\bar D^{*} \Sigma_c; 3/2^- \rangle of I=1/2 , we find

    \begin{aligned}[b] \Gamma(|\bar D^{*} \Sigma_c; 3/2^- \rangle \to \eta_c p ) =& a_3^2 \; 670\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c; 3/2^- \rangle \to J/\psi p ) =& a_3^2 \; 1.4 \times 10^{5}\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c; 3/2^- \rangle \to \bar D^{*0} \Lambda_c^+ ) =& b_3^2 \; 4.6 \times 10^{4}\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c; 3/2^- \rangle \to \bar D^{0} \Sigma_c^+ ) =& b_3^2 \; 1.4 \; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c; 3/2^- \rangle \to D^- \Sigma_c^{++} ) =& b_3^2 \; 2.7 \; {\rm{GeV}}^7 \, . \end{aligned}

    (126)

    We use the above partial decay widths to further derive their corresponding relative branching ratios. The obtained results are summarized in Table 3, where a new parameter t \equiv {b_i^2 / a_i^2} ( i=1\cdots7 ) is introduced to measure which processes occur more easily, the process depicted in Fig. 5(a) or the processes depicted in Fig. 5(b, c). We discuss these results in Sec. VI.

    Table 3

    Table 3.  Relative branching ratios of the \bar D^{(*)} \Sigma_c^{(*)} hadronic molecular states and their relative production rates in \Lambda_b^0 decays. In the 2rd-12th columns, we show the branching ratios relative to the J/\psi p channel, such as {{\cal{B}}(P_c \to \eta_c p)\over{\cal{B}}(P_c \to J/\psi p)} in the 3rd column. The parameter t \equiv {b_i^2 / a_i^2} ( i=1\cdots7 ) is introduced to measure which processes occur more easily, the process depicted in Fig. 5(a) or the processes depicted in Fig. 5(b, c). In the 13th column, we show the ratio {\cal{R}}_1(P_c) \equiv {{\cal{B}}\left(\Lambda_b^0 \rightarrow P_c K^- \right) \over {\cal{B}}\left(\Lambda_b^0 \rightarrow |\bar D^* \Sigma_c \rangle_{3/2^-} K^- \right)} , and in the 14th column, we show the ratio {\cal{R}}_2(P_c) \equiv { {\cal{B}}(\Lambda_b^0 \to P_c K^- \to J/\psi p K^-) \over {\cal{B}}(\Lambda_b^0 \to |\bar D^* \Sigma_c \rangle_{3/2^-} K^- \to J/\psi p K^-) } . To calculate {\cal{R}}_2 , we a) simply assume t=1 and b) neglect all the spin-3/2 baryons that P_c can decay into, such as the J/\psi N^* and \bar D \Sigma_c^* final states.
    ConfigurationDecay channelsProductions
    J/\psi p\eta_c p\chi_{c0} p\chi_{c1} ph_c p\bar D^{0} \Lambda_c^+\bar D^{*0} \Lambda_c^+\bar D^{0} \Sigma_c^+D^{-} \Sigma_c^{++}\bar D^{*0} \Sigma_c^+D^{*-} \Sigma_c^{++}{\cal{R}}_1{\cal{R}}_2
    |\bar D \Sigma_c; 1/2^- \rangle13.80.69t8.22.0
    |\bar D^{*} \Sigma_c; 1/2^- \rangle10.350.01610^{-4}3.4t1.2t0.12t0.23t1.20.25
    |\bar D^{*} \Sigma_c; 3/2^- \rangle10.0050.34t10^{-5}t10^{-5}t\bf1\bf1
    |\bar D \Sigma_c^*; 3/2^- \rangle10.70250t
    |\bar D^* \Sigma_c^*; 1/2^- \rangle1310.300.100.0234t1.5t0.15t0.30t0.35t0.70t4.80.09
    |\bar D^* \Sigma_c^*; 3/2^- \rangle10.0060.0080.39t10^{-5}t10^{-4}t0.04t0.08t0.180.16
    |\bar D^* \Sigma_c^*; 5/2^- \rangle
    DownLoad: CSV
    Show Table

    In this paper, we systematically investigate the seven possible \bar D^{(*)} \Sigma_c^{(*)} hadronic molecular states of I=1/2 , including \bar D \Sigma_c of J^P = {1/2}^- , \bar D^* \Sigma_c of J^P = {(1/2)}^-/ {(3/2)}^- , \bar D \Sigma_c^* of J^P = {3/2}^- , and \bar D^* \Sigma_c^* of J^P = {(1/2)}^-/ {(3/2)}^-/ {(5/2)}^-.

    First, we systematically construct their corresponding interpolating currents and calculate their masses and decay constants using QCD sum rules. The results are summarized in Table 1, supporting the interpretations of P_c(4312)^+ , P_c(4440)^+ , and P_c(4457)^+ [5] as the \bar D \Sigma_c and \bar D^* \Sigma_c molecular states. However, the accuracy of our sum rule results is not good enough to distinguish or indentify them. To better understand them, we further study their production and decay properties. The decay constants f_X extracted using QCD sum rules are important input parameters.

    Second, we use current algebra to study the production of \bar D^{(*)} \Sigma_c^{(*)} molecular states in \Lambda_b^0 decays. We derive the relative production rates

    {\cal{R}}_1(P_c) \equiv {{\cal{B}}\left(\Lambda_b^0 \rightarrow P_c K^- \right) \over {\cal{B}}\left(\Lambda_b^0 \rightarrow |\bar D^* \Sigma_c \rangle_{3/2^-} K^- \right)} \, ,

    (127)

    and the obtained results are summarized in Table 3.

    Third, we use the Fierz rearrangement of the Dirac and color indices to study the decay properties of the \bar D^{(*)} \Sigma_c^{*} molecular states, including their decays into charmonium mesons and spin-1/2 light baryons as well as charmed mesons and spin-1/2 charmed baryons, such as J/\psi p and \bar D \Lambda_c . We calculate their relative branching ratios, and the obtained results are also summarized in Table 3. The parameter t \equiv {b_i^2 / a_i^2} ( i=1\cdots7 ) is introduced to measure which processes occur more easily, the process depicted in Fig. 5(a) or the processes depicted in Fig. 5(b, c). Generally, the exchange of one light quark with another light quark may be easier than its exchange with a heavy quark [125]; therefore, it can be the case that t \geq 1 .

    In Table 3, we simply assume t=1 to further calculate the ratio {\cal{R}}_1 in the J/\psi p mass spectrum, that is,

    {\cal{R}}_2(P_c) \equiv { {\cal{B}}(\Lambda_b^0 \to P_c K^- \to J/\psi p K^-) \over {\cal{B}}(\Lambda_b^0 \to |\bar D^* \Sigma_c \rangle_{3/2^-} K^- \to J/\psi p K^-) } \, .

    (128)

    To calculate this ratio, we neglect all spin-3/2 baryons that P_c can decay into, such as the J/\psi N^* and \bar D \Sigma_c^* final states.

    Before drawing conclusions, we would like to note the following:

    ● When studying the masses and decay constants of the \bar D^{(*)} \Sigma_c^{(*)} molecular states using QCD sum rules, we calculate two-point correlation functions at the quark-gluon level as inputs, whereas the masses of charmed mesons and baryons at the hadron level are not used as input parameters. Accordingly, the uncertainty/accuracy is moderate but not sufficient to extract the binding energy. This means that our sum rule results can only suggest but not determine a) whether these \bar D^{(*)} \Sigma_c^{(*)} molecular states exist, and b) whether they are bound or resonance states. Instead, we must assume their existence. We may then use the extracted decay constants to further study their production and decay properties.

    ● When studying the relative production rates of the \bar D^{(*)} \Sigma_c^{(*)} molecular states in \Lambda_b^0 decays using current algebra, we only investigate the hidden-charm pentaquark currents that can couple to these states through an S-wave, that is, J_{1\cdots7} defined in Eqs. (26)–(40). There may be other currents coupling to these states through a P-wave, which are not considered in the present study. Accordingly, |\bar D \Sigma_c^*; 3/2^- \rangle and |\bar D^* \Sigma_c^*; 5/2^- \rangle may still be produced in \Lambda_b^0 decays through these "P-wave" currents. Note that their omission produces theoretical uncertainties.

    ● When studying the decay properties of the \bar D^{(*)} \Sigma_c^{*} molecular states via Fierz rearrangement, we consider the leading-order fall-apart decays described by color-singlet-color-singlet meson-baryon currents but neglect the {\cal{O}}(\alpha_s) corrections described by color-octet-color-octet meson-baryon currents; therefore, there may be other possible decay channels. Moreover, we do not consider the light/charmed baryon fields of J=3/2 ; hence, we cannot study their decays into the J/\psi N^* and \bar D \Sigma_c^* final states. However, we keep all light/charmed baryon fields that couple to the ground-state light/charmed baryons of J^P=1/2^+ ; hence, their decays into these final states are well investigated in this paper.

    Now, we can discuss our uncertainties. The uncertainty on our QCD sum rule results is moderate, whereas the uncertainties on the relative branching ratios as well as the two ratios {\cal{R}}_1 and {\cal{R}}_2 are significantly larger. In the present study, we work under the naïve factorization scheme; therefore, our uncertainties are significantly larger than those of the well-developed QCD factorization scheme [126128], whose uncertainty is at the 5% level when investigating conventional (heavy) hadrons [129]. However, in this paper, we only calculate the ratios, which significantly reduces our uncertainties. Accordingly, we approximately estimate the uncertainty on the relative branching ratios to be at the X^{+100\%}_{-\; 50\%} level. Owing to the omission of the "P-wave" pentaquark currents, the uncertainty on the ratio {\cal{R}}_1 is approximately estimated to be at the X^{+200\%}_{-\; 67\%} level. We further estimate the uncertainty on the ratio {\cal{R}}_2 to be at the X^{+300\%}_{-\; 75\%} level (or even larger due to the assumption that t=1 and the omission of the spin-3/2 baryons that P_c can decay into).

    Finally, we can draw conclusions using the results summarized in Table 3. The LHCb experiment [5] discovered P_c(4312)^+ , P_c(4440)^+ , and P_c(4457)^+ and, at the same time, measured their relative contributions {\cal{R}}\; \equiv \;{\cal{B}}\;(\Lambda^0_b \to P_c^+ K^-)\,{\cal{B}}\,(P_c^+ \to J/\psi p)\,/\,{\cal{B}}\,(\,\Lambda^0_b \to J/\psi p K^-) to be

    \begin{aligned}[b] {\cal{R}}(P_c(4312)^+) =& 0.30 \pm 0.07 ^{+0.34}_{-0.09} \% \, , \\ {\cal{R}}(P_c(4440)^+) =& 1.11 \pm 0.33 ^{+0.22}_{-0.10} \% \, , \\ {\cal{R}}(P_c(4457)^+) =& 0.53 \pm 0.16 ^{+0.15}_{-0.13} \% \, , \end{aligned}

    (129)

    from which we can derive

    \begin{aligned}[b] {{\cal{R}}(P_c(4312)^+) \over {\cal{R}}(P_c(4440)^+)} =& 0.27^{+0.32}_{-0.14} \, , \\ {{\cal{R}}(P_c(4457)^+) \over {\cal{R}}(P_c(4440)^+)} =& 0.48^{+0.25}_{-0.25} \, . \end{aligned}

    (130)

    These two values are approximately consistent with our results,

    \begin{aligned}[b] {\cal{R}}_2(|\bar D \Sigma_c; 1/2^- \rangle) =& {{\cal{R}}_2(|\bar D \Sigma_c; 1/2^- \rangle) \over {\cal{R}}_2(|\bar D^* \Sigma_c; 3/2^- \rangle)} \approx 2.0 \, , \\ {\cal{R}}_2(|\bar D^* \Sigma_c; 1/2^- \rangle) =& {{\cal{R}}_2(|\bar D^* \Sigma_c; 1/2^- \rangle) \over {\cal{R}}_2(|\bar D^* \Sigma_c; 3/2^- \rangle)} \approx 0.25 \, , \end{aligned}

    (131)

    given that their uncertainties are approximately at the X^{+300\%}_{-\; 75\%} level.

    Therefore, our results support the interpretations of P_c(4312)^+ , P_c(4440)^+ , and P_c(4457)^+ as \bar D \Sigma_c of J^P = {1/2}^- , \bar D^* \Sigma_c of J^P = {3/2}^- , and \bar D^* \Sigma_c of J^P = {1/2}^- , respectively. For completeness, we also investigate the interpretations of P_c(4440)^+ and P_c(4457)^+ as the \bar D^* \Sigma_c molecular states of J^P = {1/2}^- and {3/2}^- , respectively, and the results are given in Appendix C.

    Our results suggest that the \bar D^* \Sigma_c^* molecular states of J^P = 1/2^- and 3/2^- may also be observed in the J/\psi p invariant mass spectrum of \Lambda_b^0 \to J/\psi p K^- decays, and their relative contributions are estimated to be

    \begin{aligned}[b] { {\cal{B}}(\Lambda_b^0 \to |\bar D^* \Sigma_c^* \rangle_{1/2^-} K^- \to J/\psi p K^-) \over {\cal{B}}(\Lambda^0_b \to J/\psi p K^-) } \approx 0.1{\text{%}} \, , \end{aligned}

    \begin{aligned}[b] { {\cal{B}}(\Lambda_b^0 \to |\bar D^* \Sigma_c^* \rangle_{3/2^-} K^- \to J/\psi p K^-) \over {\cal{B}}(\Lambda^0_b \to J/\psi p K^-) } \approx 0.2{\text{%}} \, . \end{aligned}

    (132)

    Their relative branching ratios to the \eta_c p , \chi_{c0} p , \chi_{c1} p , h_c p , \bar D^{0} \Lambda_c^+ , \bar D^{*0} \Lambda_c^+ , \bar D^{0} \Sigma_c^+ , D^{-} \Sigma_c^{++} , \bar D^{*0} \Sigma_c^+ , and D^{*-} \Sigma_c^{++} final states are also given for future experimental searches.

    In this appendix, we list the spectral densities \rho_{1\cdots7}(s) extracted for the currents J_{1\cdots7} . In the following expressions, {\cal{F}}(s)=\left[(\alpha+\beta) m_{c}^{2}-\alpha \beta s\right], {\cal{H}}(s)=\left[m_{c}^{2}-\alpha(1-\alpha) s\right], and the integration limits are \alpha_{\rm min}={(1-\sqrt{1-4m_c^2/s})}/{2} , \alpha_{\rm max}={(1+\sqrt{1-4m_c^2/s})}/{2} , \beta_{\rm min}={(\alpha m_c^2)}/{(\alpha s-m_c^2)} , and \beta_{\rm max}=1-\alpha .

    The spectral density \rho_{1}(s) extracted for the current J_{1} is

    \begin{aligned}[b]\\[-6pt] \rho_{1}(s) =& m_c \left( \rho^{\rm pert}_{1a}(s) + \rho^{{\langle\bar qq\rangle}}_{1a}(s) + \rho^{{\langle GG\rangle}}_{1a}(s)+ \rho^{{\langle\bar qGq\rangle}}_{1a}(s) + \rho^{{\langle\bar qq\rangle}^2}_{1a}(s) + \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{1a}(s)+ \rho^{{\langle\bar qGq\rangle}^2}_{1a}(s) + \rho^{{\langle\bar qq\rangle}^3}_{1a}(s) \right) \\ &+ \not q \; \; \left( \rho^{\rm pert}_{1b}(s) + \rho^{{\langle\bar qq\rangle}}_{1b}(s) + \rho^{{\langle GG\rangle}}_{1b}(s)+ \rho^{{\langle\bar qGq\rangle}}_{1b}(s) + \rho^{{\langle\bar qq\rangle}^2}_{1b}(s) + \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{1b}(s)+ \rho^{{\langle\bar qGq\rangle}^2}_{1b}(s) + \rho^{{\langle\bar qq\rangle}^3}_{1b}(s) \right) \, , \end{aligned}\tag{A1}

    where

    \begin{aligned}[b] & \rho^{\rm pert}_{1a}(s) = {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^5 \times \frac{13 (1 - \alpha - \beta)^3}{983040 \pi ^8 \alpha ^5 \beta ^4} \Bigg\} \, , \\ & \rho^{{\langle\bar qq\rangle}}_{1a}(s) = {m_c {\langle\bar qq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^3 \times \frac{-(1 - \alpha - \beta)^2}{768 \pi ^6 \alpha ^3 \beta ^3} \Bigg\} \, , \\& \rho^{{\langle GG\rangle}}_{1a}(s) = {{\langle g_s^2GG\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta}\Bigg\{ m_c^2 {\cal{F}}(s)^2 \times \frac{13 (1 - \alpha - \beta)^3 \left(\alpha ^3+\beta ^3\right)}{1179648 \pi ^8 \alpha ^5 \beta ^4} \\ & \quad\quad\quad\quad + {\cal{F}}(s)^3 \times \frac{(\alpha +\beta -1) \left(80 \alpha ^3+\alpha ^2 (206 \beta -79)+\alpha \left(28 \beta ^2-27 \beta -1\right)-26 (\beta -1)^2 \beta \right)}{2359296 \pi ^8 \alpha ^5 \beta ^3} \Bigg\} \, , \end{aligned}

    \begin{aligned}[b] & \rho^{{\langle\bar qGq\rangle}}_{1a}(s) = {m_c{\langle g_s\bar q\sigma Gq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \times \frac{ (1 - \alpha - \beta) \left(14 \alpha ^2+2 \alpha (15 \beta -7)+(\beta -1) \beta \right)}{8192 \pi ^6 \alpha ^3 \beta ^3} \Bigg\} \, , \\ & \rho^{{\langle\bar qq\rangle}^2}_{1a}(s)= {{\langle\bar qq\rangle}^2 } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \times \frac{-29}{1536 \pi ^4 \alpha ^2 \beta } \Bigg\} \, , \\& \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{1a}(s)= {{\langle\bar qq\rangle}{\langle g_s\bar q\sigma Gq\rangle} } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta \Bigg\{ {\cal{F}}(s) \times \frac{-6 \alpha -29 \beta}{3072 \pi ^4 \alpha ^2 \beta } \Bigg\} + {\cal{H}}(s) \times \frac{55 }{3072 \pi ^4 \alpha } \Bigg\} \, , \end{aligned}

    \begin{aligned}[b] &\rho^{{\langle\bar qGq\rangle}^2}_{1a}(s)= {{\langle g_s\bar q\sigma Gq\rangle}^2 } \Bigg\{\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \frac{52 \alpha ^2-75 \alpha +29}{12288 \pi ^4 \alpha } \Bigg\} + \int^{1}_{0}{\rm d}\alpha \Bigg\{ m_c^2 \delta\left(s - {m_c^2 \over \alpha(1-\alpha)}\right) \times \frac{-13}{6144 \pi ^4 \alpha } \Bigg\}\Bigg\} \, , \\ &\rho^{{\langle\bar qq\rangle}^3}_{1a}(s)= {m_c{\langle\bar qq\rangle}^3 } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \frac{13 }{288 \pi ^2} \Bigg\} \, , \\& \rho^{\rm pert}_{1b}(s) = {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^5 \times \frac{13 (1 - \alpha - \beta)^3}{491520 \pi ^8 \alpha ^4 \beta ^4} \Bigg\} \, , \end{aligned}

    \begin{aligned}[b] &\rho^{{\langle\bar qq\rangle}}_{1b}(s) ={m_c {\langle\bar qq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^3 \times \frac{-29 (1 - \alpha - \beta)^2}{12288 \pi ^6 \alpha ^2 \beta ^3} \Bigg\} \, , \\& \rho^{{\langle GG\rangle}}_{1b}(s) ={{\langle g_s^2GG\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta}\Bigg\{ m_c^2 {\cal{F}}(s)^2 \times \frac{13 (1 - \alpha - \beta)^3 \left(\alpha ^3+\beta ^3\right)}{589824 \pi ^8 \alpha ^4 \beta ^4} \\ &\quad\quad\quad\quad + {\cal{F}}(s)^3 \times \frac{(\alpha +\beta -1) \left(167 \alpha ^2+\alpha (223 \beta -166)+80 \beta ^2-79 \beta -1\right)}{2359296 \pi ^8 \alpha ^3 \beta ^3} \Bigg\} \, , \\ & \rho^{{\langle\bar qGq\rangle}}_{1b}(s) = {m_c{\langle g_s\bar q\sigma Gq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \times \frac{ (1 - \alpha - \beta) \left(110 \alpha ^2+\alpha (217 \beta -110)+3 (\beta -1) \beta \right)}{32768 \pi ^6 \alpha ^2 \beta ^3} \Bigg\} \, , \end{aligned}

    \begin{aligned}[b]& \rho^{{\langle\bar qq\rangle}^2}_{1b}(s)= {{\langle\bar qq\rangle}^2 } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \times \frac{-1}{96 \pi ^4 \alpha \beta } \Bigg\} \, , \\& \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{1b}(s)= {{\langle\bar qq\rangle}{\langle g_s\bar q\sigma Gq\rangle} } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta \Bigg\{ {\cal{F}}(s) \times \frac{-5 \alpha -15 \beta }{3072 \pi ^4 \alpha \beta } \Bigg\} + {\cal{H}}(s) \times \frac{31 }{3072 \pi ^4} \Bigg\} \, , \\& \rho^{{\langle\bar qGq\rangle}^2}_{1b}(s)= {{\langle g_s\bar q\sigma Gq\rangle}^2 } \Bigg\{ \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \frac{30 \alpha ^2-40 \alpha +15}{12288 \pi ^4} \Bigg\} + \int^{1}_{0}{\rm d}\alpha \Bigg\{ m_c^2 \delta\left(s - {m_c^2 \over \alpha(1-\alpha)}\right) \times \frac{-5 }{4096 \pi ^4} \Bigg\} \Bigg\} \, , \\ & \rho^{{\langle\bar qq\rangle}^3}_{1b}(s)= {m_c{\langle\bar qq\rangle}^3 } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \frac{13 \alpha }{576 \pi ^2} \Bigg\} \, . \end{aligned}

    The spectral density \rho_{2}(s) extracted for the current J_{2} is

    \begin{aligned}[b] \rho_{2}(s)=& m_c \left( \rho^{\rm pert}_{2a}(s) + \rho^{{\langle\bar qq\rangle}}_{2a}(s) + \rho^{{\langle GG\rangle}}_{2a}(s)+ \rho^{{\langle\bar qGq\rangle}}_{2a}(s) + \rho^{{\langle\bar qq\rangle}^2}_{2a}(s) + \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{2a}(s)+ \rho^{{\langle\bar qGq\rangle}^2}_{2a}(s) + \rho^{{\langle\bar qq\rangle}^3}_{2a}(s) \right) \\ &+ \not q \; \; \left( \rho^{pert}_{2b}(s) + \rho^{{\langle\bar qq\rangle}}_{2b}(s) + \rho^{{\langle GG\rangle}}_{2b}(s)+ \rho^{{\langle\bar qGq\rangle}}_{2b}(s) + \rho^{{\langle\bar qq\rangle}^2}_{2b}(s) + \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{2b}(s)+ \rho^{{\langle\bar qGq\rangle}^2}_{2b}(s) + \rho^{{\langle\bar qq\rangle}^3}_{2b}(s) \right) \, , \\ \end{aligned}\tag{A2}

    where

    \begin{aligned}[b] &\rho^{\rm pert}_{2a}(s)= {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^5 \times \frac{(1 -\alpha -\beta)^3}{49152 \pi ^8 \alpha ^5 \beta ^4} \Bigg\} \, , \\& \rho^{{\langle\bar qq\rangle}}_{2a}(s) = {m_c {\langle\bar qq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^3 \times \frac{-13 (1 -\alpha -\beta)^2}{3072 \pi ^6 \alpha ^3 \beta ^3} \Bigg\} \, , \\& \rho^{{\langle GG\rangle}}_{2a}(s) = {{\langle g_s^2GG\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta}\Bigg\{ m_c^2 {\cal{F}}(s)^2 \times \frac{5 (1 - \alpha - \beta)^3 \left(\alpha ^3+\beta ^3\right)}{294912 \pi ^8 \alpha ^5 \beta ^4} \\ & \quad\quad\quad\quad + {\cal{F}}(s)^3 \times \frac{(1 - \alpha - \beta) \left(32 \alpha ^3-\alpha ^2 (16 \beta +31)+\alpha \left(-14 \beta ^2+15 \beta -1\right)+10 (\beta -1)^2 \beta \right)}{589824 \pi ^8 \alpha ^5 \beta ^3} \Bigg\} \, ,\\& \rho^{{\langle\bar qGq\rangle}}_{2a}(s) = {m_c{\langle g_s\bar q\sigma Gq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \times \frac{ (1 - \alpha - \beta) (23 \alpha +2 \beta -2)}{4096 \pi ^6 \alpha ^3 \beta ^2} \Bigg\} \, , \\ & \rho^{{\langle\bar qq\rangle}^2}_{2a}(s)= {{\langle\bar qq\rangle}^2 } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \times \frac{-5}{192 \pi ^4 \alpha ^2 \beta } \Bigg\} \, , \\ & \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{2a}(s)= {{\langle\bar qq\rangle}{\langle g_s\bar q\sigma Gq\rangle} } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta \Bigg\{ {\cal{F}}(s) \times \frac{7 \alpha -20 \beta}{1536 \pi ^4 \alpha ^2 \beta } \Bigg\} + {\cal{H}}(s) \times \frac{11 }{512 \pi ^4 \alpha } \Bigg\} \, , \\& \rho^{{\langle\bar qGq\rangle}^2}_{2a}(s)= {{\langle g_s\bar q\sigma Gq\rangle}^2 } \Bigg\{ \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \frac{26 \alpha ^2-53 \alpha +20}{6144 \pi ^4 \alpha } \Bigg\} + \int^{1}_{0}{\rm d}\alpha \Bigg\{ m_c^2 \delta\left(s - {m_c^2 \over \alpha(1-\alpha)}\right) \times \frac{-13}{6144 \pi ^4 \alpha } \Bigg\} \Bigg\} \, , \end{aligned}

    \begin{aligned}[b] \rho^{{\langle\bar qq\rangle}^3}_{2a}(s)= {m_c{\langle\bar qq\rangle}^3 } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \frac{23 }{144 \pi ^2} \Bigg\} \, , \end{aligned}

    \begin{aligned}[b] & \rho^{\rm pert}_{2b}(s) = {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^5 \times \frac{23 (1 -\alpha -\beta)^3}{245760 \pi ^8 \alpha ^4 \beta ^4} \Bigg\} \, , \\& \rho^{{\langle\bar qq\rangle}}_{2b}(s) ={m_c {\langle\bar qq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^3 \times \frac{-5(1 -\alpha -\beta)^2}{1536 \pi ^6 \alpha ^2 \beta ^3} \Bigg\} \, , \\ & \rho^{{\langle GG\rangle}}_{2b}(s) = {{\langle g_s^2GG\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta}\Bigg\{ m_c^2 {\cal{F}}(s)^2 \times \frac{23(1 - \alpha - \beta)^3 \left(\alpha ^3+\beta ^3\right)}{294912 \pi ^8 \alpha ^4 \beta ^4} \\ &\quad\quad\quad\quad + {\cal{F}}(s)^3 \times \frac{(1 - \alpha - \beta) \left(\alpha ^2-\alpha (11 \beta +1)-24 (\beta -1) \beta \right)}{196608 \pi ^8 \alpha ^3 \beta ^3} \Bigg\} \, , \end{aligned}

    \begin{aligned}[b] &\rho^{{\langle\bar qGq\rangle}}_{2b}(s) = {m_c{\langle g_s\bar q\sigma Gq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \times \frac{13 (1 - \alpha - \beta)}{4096 \pi ^6 \alpha \beta ^2} \Bigg\} \, , \\& \rho^{{\langle\bar qq\rangle}^2}_{2b}(s)= {{\langle\bar qq\rangle}^2 } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \times \frac{-13}{384 \pi ^4 \alpha \beta } \Bigg\} \, , \end{aligned}

    \begin{aligned}[b] & \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{2b}(s)= {{\langle\bar qq\rangle}{\langle g_s\bar q\sigma Gq\rangle} } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta \Bigg\{ {\cal{F}}(s) \times \frac{ - 5 \alpha - 24 \beta}{1536 \pi ^4 \alpha \beta } \Bigg\} + {\cal{H}}(s) \times \frac{47 }{1536 \pi ^4} \Bigg\} \, , \\& \rho^{{\langle\bar qGq\rangle}^2}_{2b}(s)= {{\langle g_s\bar q\sigma Gq\rangle}^2 } \Bigg\{ \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \frac{42 \alpha ^2-61 \alpha +24}{6144 \pi ^4} \Bigg\} +\int^{1}_{0}{\rm d}\alpha \Bigg\{ m_c^2 \delta\left(s - {m_c^2 \over \alpha(1-\alpha)}\right) \times \frac{-7}{2048 \pi ^4} \Bigg\} \Bigg\} \, , \\& \rho^{{\langle\bar qq\rangle}^3}_{2b}(s)= {m_c{\langle\bar qq\rangle}^3 } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \frac{5 \alpha }{144 \pi ^2} \Bigg\} \, . \end{aligned}

    The spectral density \rho_{3}(s) extracted for the current J_{3} is

    \begin{aligned}[b] \rho_{3}(s) =& m_c \left( \rho^{\rm pert}_{3a}(s) + \rho^{{\langle\bar qq\rangle}}_{3a}(s) + \rho^{{\langle GG\rangle}}_{3a}(s)+ \rho^{{\langle\bar qGq\rangle}}_{3a}(s) + \rho^{{\langle\bar qq\rangle}^2}_{3a}(s) + \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{3a}(s)+ \rho^{{\langle\bar qGq\rangle}^2}_{3a}(s) + \rho^{{\langle\bar qq\rangle}^3}_{3a}(s) \right) \\ &+ \not q \; \; \left( \rho^{\rm pert}_{3b}(s) + \rho^{{\langle\bar qq\rangle}}_{3b}(s) + \rho^{{\langle GG\rangle}}_{3b}(s)+ \rho^{{\langle\bar qGq\rangle}}_{3b}(s) + \rho^{{\langle\bar qq\rangle}^2}_{3b}(s) + \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{3b}(s)+ \rho^{{\langle\bar qGq\rangle}^2}_{3b}(s) + \rho^{{\langle\bar qq\rangle}^3}_{3b}(s) \right) \, ,\ \end{aligned}\tag{A3}

    where

    \begin{aligned}[b] & \rho^{\rm pert}_{3a}(s) = {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^5 \times \frac{7 (1 - \alpha - \beta)^3 (\alpha +\beta +4)}{3932160 \pi ^8 \alpha ^5 \beta ^4} \Bigg\} \, , \\& \rho^{{\langle\bar qq\rangle}}_{3a}(s) = {m_c {\langle\bar qq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^3 \times \frac{- (1 - \alpha - \beta)^2 (8 \alpha +8 \beta +157)}{147456 \pi ^6 \alpha ^3 \beta ^3} \Bigg\} \, , \\& \rho^{{\langle GG\rangle}}_{3a}(s) = {{\langle g_s^2GG\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta}\Bigg\{ m_c^2 {\cal{F}}(s)^2 \times \frac{7 (1 - \alpha - \beta)^3 (\alpha +\beta +4) \left(\alpha ^3+\beta ^3\right)}{4718592 \pi ^8 \alpha ^5 \beta ^4} \\ &\quad\quad\quad\quad + {\cal{F}}(s)^3 \times \Bigg( \frac{53 \alpha ^5+\alpha ^4 (530 \beta -464)+45 \alpha ^3 \left(22 \beta ^2-16 \beta +17\right)+70 \alpha ^2 \left(8 \beta ^3-3 \beta ^2-5\right)}{28311552 \pi ^8 \alpha ^5 \beta ^3} \\ &\quad\quad\quad\quad+ \frac{\alpha (\beta -1)^2 \left(5 \beta ^2+14 \beta -4\right)-42 (\beta -1)^3 \beta (\beta +4)}{28311552 \pi ^8 \alpha ^5 \beta ^3} \Bigg) \Bigg\} \, , \end{aligned}

    \begin{aligned}[b] & \rho^{{\langle\bar qGq\rangle}}_{3a}(s) = {m_c{\langle g_s\bar q\sigma Gq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \; \frac{(1 - \alpha - \beta) \left(42 \alpha ^2+\alpha (50 \beta +311)+8 \beta ^2+14 \beta -22\right)}{196608 \pi ^6 \alpha ^3 \beta ^2} \Bigg\} \, , \\ &\rho^{{\langle\bar qq\rangle}^2}_{3a}(s)= {{\langle\bar qq\rangle}^2 } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \times \frac{-4 \alpha -4 \beta -1}{384 \pi ^4 \alpha ^2 \beta } \Bigg\} \, , \end{aligned}

    \begin{aligned}[b] & \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{3a}(s)= {{\langle\bar qq\rangle}{\langle g_s\bar q\sigma Gq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s) \times \frac{4 \alpha ^2+\alpha (49-1128 \beta )-96 \beta (4 \beta +1)}{73728 \pi ^4 \alpha ^2 \beta } \Bigg\} \\ &\quad\quad\quad\;\;\quad\quad+ {{\langle\bar qq\rangle}{\langle g_s\bar q\sigma Gq\rangle} } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ {\cal{H}}(s) \times \frac{935 }{73728 \pi ^4 \alpha } \Bigg\} \, , \\& \rho^{{\langle\bar qGq\rangle}^2}_{3a}(s)= {{\langle g_s\bar q\sigma Gq\rangle}^2 } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta \Bigg\{ \frac{\alpha -96 \beta}{73728 \pi ^4 \alpha } \Bigg\} + \frac{546 \alpha ^2-1079 \alpha +480}{294912 \pi ^4 \alpha } \Bigg\} \\ &\quad\quad\quad\;\;\quad+ {{\langle g_s\bar q\sigma Gq\rangle}^2 } \int^{1}_{0}{\rm d}\alpha \Bigg\{ m_c^2 \delta\left(s - {m_c^2 \over \alpha(1-\alpha)}\right) \times \frac{-455 }{294912 \pi ^4 \alpha } \Bigg\} \, , \\& \rho^{{\langle\bar qq\rangle}^3}_{3a}(s)= {m_c{\langle\bar qq\rangle}^3 } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \frac{9}{256 \pi ^2} \Bigg\} \, , \\ & \rho^{\rm pert}_{3b}(s) = {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^5 \times \frac{9 (1 - \alpha - \beta)^3 (\alpha +\beta +2)}{1310720 \pi ^8 \alpha ^4 \beta ^4} \Bigg\} \, , \end{aligned}

    \begin{aligned}[b] & \rho^{{\langle\bar qq\rangle}}_{3b}(s) = {m_c {\langle\bar qq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^3 \times \frac{-5 (1 - \alpha - \beta)^2}{3072 \pi ^6 \alpha ^2 \beta ^3} \Bigg\} \, , \\& \rho^{{\langle GG\rangle}}_{3b}(s) = {{\langle g_s^2GG\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta}\Bigg\{ m_c^2 {\cal{F}}(s)^2 \times \frac{3 (1 - \alpha - \beta)^3 (\alpha +\beta +2) \left(\alpha ^3+\beta ^3\right)}{524288 \pi ^8 \alpha ^4 \beta ^4} + {\cal{F}}(s)^3 \\ &\quad\quad\quad\quad\times \frac{(\alpha +\beta -1) \left(243 \alpha ^3+\alpha ^2 (673 \beta -834)+\alpha \left(761 \beta ^2-743 \beta +588\right)+331 \beta ^3+103 \beta ^2-437 \beta +3\right)}{28311552 \pi ^8 \alpha ^3 \beta ^3} \Bigg\} \, , \\& \rho^{{\langle\bar qGq\rangle}}_{3b}(s) = {m_c{\langle g_s\bar q\sigma Gq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \times \frac{5 (1 - \alpha - \beta) (94 \alpha +3 \beta -3)}{196608 \pi ^6 \alpha ^2 \beta ^2} \Bigg\} \, , \\& \rho^{{\langle\bar qq\rangle}^2}_{3b}(s)= {{\langle\bar qq\rangle}^2 } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \times \frac{-5 (12 \alpha +12 \beta -1)}{6144 \pi ^4 \alpha \beta } \Bigg\} \, , \end{aligned}

    The spectral density \rho_{4}(s) extracted for the current J_{4} is

    \begin{aligned}[b] \rho_{4}(s) =& m_c \left( \rho^{pert}_{4a}(s) + \rho^{{\langle\bar qq\rangle}}_{4a}(s) + \rho^{{\langle GG\rangle}}_{4a}(s)+ \rho^{{\langle\bar qGq\rangle}}_{4a}(s) + \rho^{{\langle\bar qq\rangle}^2}_{4a}(s) + \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{4a}(s)+ \rho^{{\langle\bar qGq\rangle}^2}_{4a}(s) + \rho^{{\langle\bar qq\rangle}^3}_{4a}(s) \right) \\ &+ \not q \; \; \left( \rho^{pert}_{4b}(s) + \rho^{{\langle\bar qq\rangle}}_{4b}(s) + \rho^{{\langle GG\rangle}}_{4b}(s)+ \rho^{{\langle\bar qGq\rangle}}_{4b}(s) + \rho^{{\langle\bar qq\rangle}^2}_{4b}(s) + \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{4b}(s)+ \rho^{{\langle\bar qGq\rangle}^2}_{4b}(s) + \rho^{{\langle\bar qq\rangle}^3}_{4b}(s) \right) \, , \end{aligned}\tag{A4}

    where

    \begin{aligned}[b] & \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{3b}(s)= {{\langle\bar qq\rangle}{\langle g_s\bar q\sigma Gq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s) \times \frac{- 24 \alpha ^2 - \alpha (1088 \beta -61) - 4 \beta (94 \beta -21)}{73728 \pi ^4 \alpha \beta } \Bigg\} \\ &\quad\quad\quad\quad\;\;\quad+ {{\langle\bar qq\rangle}{\langle g_s\bar q\sigma Gq\rangle} } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ {\cal{H}}(s) \times \frac{661 }{73728 \pi ^4} \Bigg\} \, , \end{aligned}

    \begin{aligned}[b] &\rho^{{\langle\bar qGq\rangle}^2}_{3b}(s)= {{\langle g_s\bar q\sigma Gq\rangle}^2 } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta \Bigg\{ \frac{ - 3 \alpha - 47 \beta }{36864 \pi ^4} \Bigg\} + \frac{334 \alpha ^2-663 \alpha +292}{294912 \pi ^4} \Bigg\} \\ &\quad\;\;\quad\quad\quad+ {{\langle g_s\bar q\sigma Gq\rangle}^2 } \int^{1}_{0}{\rm d}\alpha \Bigg\{ m_c^2 \delta\left(s - {m_c^2 \over \alpha(1-\alpha)}\right) \times \frac{-331}{294912 \pi ^4} \Bigg\} \, , \\ &\rho^{{\langle\bar qq\rangle}^3}_{3b}(s)= {m_c{\langle\bar qq\rangle}^3 } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \frac{35 \alpha }{2304 \pi ^2} \Bigg\} \, .\\ & \rho^{\rm pert}_{4a}(s) = {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^5 \times \frac{13 (1 - \alpha - \beta)^3 (\alpha +\beta +4)}{15728640 \pi ^8 \alpha ^5 \beta ^4} \Bigg\} \, , \\& \rho^{{\langle\bar qq\rangle}}_{4a}(s) = {m_c {\langle\bar qq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^3 \times \frac{-(1 - \alpha -\beta)^2 (14 \alpha +14 \beta +43)}{147456 \pi ^6 \alpha ^3 \beta ^3} \Bigg\} \, , \end{aligned}

    \begin{aligned}[b] & \rho^{{\langle GG\rangle}}_{4a}(s) = {{\langle g_s^2GG\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta}\Bigg\{ m_c^2 {\cal{F}}(s)^2 \times \frac{13 (1 - \alpha - \beta)^3 (\alpha +\beta +4) \left(\alpha ^3+\beta ^3\right)}{18874368 \pi ^8 \alpha ^5 \beta ^4} \\ &\quad\quad\quad\quad + {\cal{F}}(s)^3 \times \Bigg\{ \frac{341 \alpha ^5+\alpha ^4 (598 \beta +220)-9 \alpha ^3 \left(10 \beta ^2-130 \beta +163\right)}{113246208 \pi ^8 \alpha ^5 \beta ^3} \\ & \quad\quad\quad\quad + \frac{\alpha ^2 \left(-688 \beta ^3+714 \beta ^2-936 \beta +910\right)-\alpha (\beta -1)^2 \left(419 \beta ^2+1152 \beta +4\right)-78 (\beta -1)^3 \beta (\beta +4)}{113246208 \pi ^8 \alpha ^5 \beta ^3} \Bigg\} \, , \\& \rho^{{\langle\bar qGq\rangle}}_{4a}(s) = {m_c{\langle g_s\bar q\sigma Gq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \\ &\quad\quad\quad\quad \times \frac{(1 - \alpha - \beta) \left(164 \alpha ^3+4 \alpha ^2 (137 \beta +74)+\alpha \left(382 \beta ^2+693 \beta -460\right)-2 \beta \left(\beta ^2+4 \beta -5\right)\right)}{1179648 \pi ^6 \alpha ^3 \beta ^3} \Bigg\} \, , \end{aligned}

    \begin{aligned}[b] & \rho^{{\langle\bar qq\rangle}^2}_{4a}(s)= {{\langle\bar qq\rangle}^2 } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \times \frac{- 4 \alpha - 4 \beta -85 }{24576 \pi ^4 \alpha ^2 \beta } \Bigg\} \, , \\& \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{4a}(s)= {{\langle\bar qq\rangle}{\langle g_s\bar q\sigma Gq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s) \times \frac{- 16 \alpha ^2 - \alpha (40 \beta +46) + \beta (4 \beta +85)}{147456 \pi ^4 \alpha ^2 \beta } \Bigg\} \\ &\quad\quad\;\quad\quad\quad+ {{\langle\bar qq\rangle}{\langle g_s\bar q\sigma Gq\rangle} } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ {\cal{H}}(s) \times \frac{509}{147456 \pi ^4 \alpha } \Bigg\} \, , \\ &\rho^{{\langle\bar qGq\rangle}^2}_{4a}(s)= {{\langle g_s\bar q\sigma Gq\rangle}^2 } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta \Bigg\{ \frac{- 4 \alpha + \beta }{147456 \pi ^4 \alpha } \Bigg\} + \frac{468 \alpha ^2-317 \alpha -89}{589824 \pi ^4 \alpha } \Bigg\} \\&\quad\quad\quad\;\;\quad+ {{\langle g_s\bar q\sigma Gq\rangle}^2 } \int^{1}_{0}{\rm d}\alpha \Bigg\{ m_c^2 \delta\left(s - {m_c^2 \over \alpha(1-\alpha)}\right) \times \frac{-121 }{294912 \pi ^4 \alpha } \Bigg\} \, , \\&\rho^{{\langle\bar qq\rangle}^3}_{4a}(s)= {m_c{\langle\bar qq\rangle}^3 } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \frac{13 }{1536 \pi ^2} \Bigg\} \, , \\& \rho^{\rm pert}_{4b}(s) = {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^5 \times \frac{13 (1 - \alpha - \beta)^3 (\alpha +\beta +2)}{7864320 \pi ^8 \alpha ^4 \beta ^4} \Bigg\} \, , \\& \rho^{{\langle\bar qq\rangle}}_{4b}(s) = {m_c {\langle\bar qq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^3 \times \frac{- (1 - \alpha - \beta)^2 (112 \alpha +112 \beta +155)}{589824 \pi ^6 \alpha ^2 \beta ^3} \Bigg\} \, , \\ & \rho^{{\langle GG\rangle}}_{4b}(s) = {{\langle g_s^2GG\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta}\Bigg\{ m_c^2 {\cal{F}}(s)^2 \times \frac{13 (1 - \alpha - \beta)^3 \left(\alpha ^4+\alpha ^3 (\beta +2)+\alpha \beta ^3+\beta ^3 (\beta +2)\right)}{9437184 \pi ^8 \alpha ^4 \beta ^4} \end{aligned}

    \begin{aligned}[b] & \quad\quad\quad\quad + {\cal{F}}(s)^3 \times \frac{5 (\alpha +\beta -1) \left(136 \alpha ^3+\alpha ^2 (176 \beta +29)+\alpha \left(40 \beta ^2+69 \beta -166\right)-80 \beta ^2+79 \beta +1\right)}{113246208 \pi ^8 \alpha ^3 \beta ^3} \Bigg\} \, , \\& \rho^{{\langle\bar qGq\rangle}}_{4b}(s) = {m_c{\langle g_s\bar q\sigma Gq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \\ &\quad\quad\quad\quad\times \frac{(1 - \alpha - \beta) \left(1312 \alpha ^3+\alpha ^2 (4400 \beta +358)+\alpha \left(3088 \beta ^2+1441 \beta -1670\right)-45 (\beta -1) \beta \right)}{4718592 \pi ^6 \alpha ^2 \beta ^3} \Bigg\} \, , \end{aligned}

    \begin{aligned}[b] &\rho^{{\langle\bar qq\rangle}^2}_{4b}(s)= {{\langle\bar qq\rangle}^2 } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \times \frac{- 2 \alpha - 2 \beta - 17}{6144 \pi ^4 \alpha \beta } \Bigg\} \, , \\& \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{4b}(s)= {{\langle\bar qq\rangle}{\langle g_s\bar q\sigma Gq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s) \times \frac{- 32 \alpha ^2 - \alpha (88 \beta +27) + 75 \beta}{147456 \pi ^4 \alpha \beta } \Bigg\} \\ &\quad\quad\quad\quad\;\;\quad+{{\langle\bar qq\rangle}{\langle g_s\bar q\sigma Gq\rangle} } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ {\cal{H}}(s) \times \frac{437 }{147456 \pi ^4} \Bigg\} \, , \end{aligned}

    \begin{aligned}[b] & \rho^{{\langle\bar qGq\rangle}^2}_{4b}(s)={{\langle g_s\bar q\sigma Gq\rangle}^2 } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta \Bigg\{ \frac{-\alpha }{18432 \pi ^4} \Bigg\} + \frac{386 \alpha ^2-252 \alpha -75}{589824 \pi ^4} \Bigg\} \\ &\quad\;\;\quad\quad\quad+ {{\langle g_s\bar q\sigma Gq\rangle}^2 } \int^{1}_{0}{\rm d}\alpha \Bigg\{ m_c^2 \delta\left(s - {m_c^2 \over \alpha(1-\alpha)}\right) \times \frac{-209 }{589824 \pi ^4}\Bigg\} \, , \\ & \rho^{{\langle\bar qq\rangle}^3}_{4b}(s)= {m_c{\langle\bar qq\rangle}^3 } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \frac{65 \alpha }{9216 \pi ^2} \Bigg\} \, . \end{aligned}

    The spectral density \rho_{5}(s) extracted for the current J_{5} is

    \begin{aligned}[b] \rho_{5}(s) =& m_c \left( \rho^{\rm pert}_{5a}(s) + \rho^{{\langle\bar qq\rangle}}_{5a}(s) + \rho^{{\langle GG\rangle}}_{5a}(s)+ \rho^{{\langle\bar qGq\rangle}}_{5a}(s) + \rho^{{\langle\bar qq\rangle}^2}_{5a}(s) + \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{5a}(s)+ \rho^{{\langle\bar qGq\rangle}^2}_{5a}(s) + \rho^{{\langle\bar qq\rangle}^3}_{5a}(s) \right) \\ &+ \not q \; \; \left( \rho^{\rm pert}_{5b}(s) + \rho^{{\langle\bar qq\rangle}}_{5b}(s) + \rho^{{\langle GG\rangle}}_{5b}(s)+ \rho^{{\langle\bar qGq\rangle}}_{5b}(s) + \rho^{{\langle\bar qq\rangle}^2}_{5b}(s) + \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{5b}(s)+ \rho^{{\langle\bar qGq\rangle}^2}_{5b}(s) + \rho^{{\langle\bar qq\rangle}^3}_{5b}(s) \right) \, , \\ \end{aligned}\tag{A5}

    where

    \begin{aligned}[b] & \rho^{\rm pert}_{5a}(s) ={\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^5 \times \frac{3 (1 - \alpha - \beta)^3}{262144 \pi ^8 \alpha ^5 \beta ^4} \Bigg\} \, , \\& \rho^{{\langle\bar qq\rangle}}_{5a}(s) = {m_c {\langle\bar qq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^3 \times \frac{-11(1-\alpha -\beta)^2}{16384 \pi ^6 \alpha ^3 \beta ^3} \Bigg\} \, , \end{aligned}

    \begin{aligned}[b] & \rho^{{\langle GG\rangle}}_{5a}(s) = {{\langle g_s^2GG\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta}\Bigg\{ m_c^2 {\cal{F}}(s)^2 \times \frac{5 (1 -\alpha -\beta)^3 \left(\alpha ^3+\beta ^3\right)}{524288 \pi ^8 \alpha ^5 \beta ^4} \\ &\quad\quad\quad\quad + {\cal{F}}(s)^3 \times \frac{ (1 - \alpha -\beta) \left(4 \alpha ^3+\alpha ^2 (92 \beta -5)+\alpha \left(94 \beta ^2-95 \beta +1\right)+30 (\beta -1)^2 \beta \right)}{3145728 \pi ^8 \alpha ^5 \beta ^3} \Bigg\} \, , \\& \rho^{{\langle\bar qGq\rangle}}_{5a}(s) = {m_c{\langle g_s\bar q\sigma Gq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \times \frac{45 (1 - \alpha - \beta)}{65536 \pi ^6 \alpha ^2 \beta ^2} \Bigg\} \, , \\& \rho^{{\langle\bar qq\rangle}^2}_{5a}(s)= {{\langle\bar qq\rangle}^2 } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \times \frac{-5}{1024 \pi ^4 \alpha ^2 \beta } \Bigg\} \, , \end{aligned}

    \begin{aligned}[b] & \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{5a}(s)= {{\langle\bar qq\rangle}{\langle g_s\bar q\sigma Gq\rangle} } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta \Bigg\{ {\cal{F}}(s) \times \frac{-\alpha +20 \beta}{24576 \pi ^4 \alpha ^2 \beta } \Bigg\} + {\cal{H}}(s) \times \frac{97 }{24576 \pi ^4 \alpha } \Bigg\} \, , \\ & \rho^{{\langle\bar qGq\rangle}^2}_{5a}(s)={{\langle g_s\bar q\sigma Gq\rangle}^2 } \Bigg\{ \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \frac{74 \alpha ^2-53 \alpha -20}{98304 \pi ^4 \alpha } \Bigg\} + \int^{1}_{0}{\rm d}\alpha \Bigg\{ m_c^2 \delta\left(s - {m_c^2 \over \alpha(1-\alpha)}\right) \times \frac{-37}{98304 \pi ^4 \alpha } \Bigg\}\Bigg\} \, , \\& \rho^{{\langle\bar qq\rangle}^3}_{5a}(s)= {m_c{\langle\bar qq\rangle}^3 } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \frac{7}{256 \pi ^2} \Bigg\} \, , \\& \rho^{\rm pert}_{5b}(s) ={\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^5 \times \frac{21 (1-\alpha -\beta)^3}{1310720 \pi ^8 \alpha ^4 \beta ^4} \Bigg\} \, , \end{aligned}

    \begin{aligned}[b] & \rho^{{\langle\bar qq\rangle}}_{5b}(s) = {m_c {\langle\bar qq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^3 \times \frac{-5(1-\alpha -\beta)^2}{8192 \pi ^6 \alpha ^2 \beta ^3} \Bigg\} \, , \\& \rho^{{\langle GG\rangle}}_{5b}(s) = {{\langle g_s^2GG\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta}\Bigg\{ m_c^2 {\cal{F}}(s)^2 \times \frac{7(1 - \alpha -\beta)^3 \left(\alpha ^3+\beta ^3\right)}{524288 \pi ^8 \alpha ^4 \beta ^4} \\ & \quad\quad\;\;\quad\quad+ {\cal{F}}(s)^3 \times \frac{(\alpha +\beta -1) \left(17 \alpha ^2-\alpha (179 \beta +13)-64 \beta ^2+68 \beta -4\right)}{9437184 \pi ^8 \alpha ^3 \beta ^3} \Bigg\} \, , \end{aligned}

    \begin{aligned}[b] &\rho^{{\langle\bar qGq\rangle}}_{5b}(s) = {m_c{\langle g_s\bar q\sigma Gq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \times \frac{(35 \alpha -2 \beta +2) (1-\alpha -\beta)}{65536 \pi ^6 \alpha ^2 \beta ^2} \Bigg\} \, , \\& \rho^{{\langle\bar qq\rangle}^2}_{5b}(s)= {{\langle\bar qq\rangle}^2 } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \times \frac{-11}{2048 \pi ^4 \alpha \beta } \Bigg\} \, , \\& \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{5b}(s)= {{\langle\bar qq\rangle}{\langle g_s\bar q\sigma Gq\rangle} } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta \Bigg\{ {\cal{F}}(s) \times \frac{-13 \alpha +16 \beta }{24576 \pi ^4 \alpha \beta } \Bigg\} + {\cal{H}}(s) \times \frac{37 }{8192 \pi ^4} \Bigg\} \, , \end{aligned}

    \begin{aligned}[b] & \rho^{{\langle\bar qGq\rangle}^2}_{5b}(s)= {{\langle g_s\bar q\sigma Gq\rangle}^2 } \Bigg\{ \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \frac{90 \alpha ^2-61 \alpha -16}{98304 \pi ^4} \Bigg\} + \int^{1}_{0}{\rm d}\alpha \Bigg\{ m_c^2 \delta\left(s - {m_c^2 \over \alpha(1-\alpha)}\right) \times \frac{-15}{32768 \pi ^4} \Bigg\} \Bigg\} \, , \\& \rho^{{\langle\bar qq\rangle}^3}_{5b}(s)= {m_c{\langle\bar qq\rangle}^3 } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \frac{5 \alpha }{256 \pi ^2} \Bigg\} \, . \end{aligned}

    The spectral density \rho_{6}(s) extracted for the current J_{6} is

    \begin{aligned}[b] \rho_{6}(s) =& m_c \left( \rho^{\rm pert}_{6a}(s) + \rho^{{\langle\bar qq\rangle}}_{6a}(s) + \rho^{{\langle GG\rangle}}_{6a}(s)+ \rho^{{\langle\bar qGq\rangle}}_{6a}(s) + \rho^{{\langle\bar qq\rangle}^2}_{6a}(s) + \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{6a}(s)+ \rho^{{\langle\bar qGq\rangle}^2}_{6a}(s) + \rho^{{\langle\bar qq\rangle}^3}_{6a}(s) \right) \\ &+\not q \; \; \left( \rho^{\rm pert}_{6b}(s) + \rho^{{\langle\bar qq\rangle}}_{6b}(s) + \rho^{{\langle GG\rangle}}_{6b}(s)+ \rho^{{\langle\bar qGq\rangle}}_{6b}(s) + \rho^{{\langle\bar qq\rangle}^2}_{6b}(s) + \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{6b}(s)+ \rho^{{\langle\bar qGq\rangle}^2}_{6b}(s) + \rho^{{\langle\bar qq\rangle}^3}_{6b}(s) \right) \, , \end{aligned}\tag{A6}

    where

    \begin{aligned}[b]& \rho^{\rm pert}_{6a}(s) = {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^5 \times \frac{7 (1 - \alpha - \beta)^3 (\alpha +\beta +4)}{15728640 \pi ^8 \alpha ^5 \beta ^4} \Bigg\} \, , \\& \rho^{{\langle\bar qq\rangle}}_{6a}(s) = {m_c {\langle\bar qq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^3 \times \frac{-5(1 - \alpha - \beta)^2 (8 \alpha +8 \beta +31)}{196608 \pi ^6 \alpha ^3 \beta ^3} \Bigg\} \, , \\& \rho^{{\langle GG\rangle}}_{6a}(s) = {{\langle g_s^2GG\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta}\Bigg\{ m_c^2 {\cal{F}}(s)^2 \times \frac{7(1 - \alpha - \beta)^3 (\alpha +\beta +4) \left(\alpha ^3+\beta ^3\right)}{18874368 \pi ^8 \alpha ^5 \beta ^4} \end{aligned}

    \begin{aligned}[b] &\quad\quad\quad\quad+ {\cal{F}}(s)^3 \times \Bigg\{ \frac{-391 \alpha^5 - 2 \alpha ^4 (839 \beta +326) - 3 \alpha ^3 \left(766 \beta ^2-96 \beta -819\right) - 42 (\beta -1)^3 \beta (\beta +4)}{113246208 \pi ^8 \alpha ^5 \beta ^3} \\ &\quad\quad\quad\quad+ \frac{-2 \alpha ^2 \left(584 \beta ^3-417 \beta ^2-864 \beta +697\right) - \alpha (\beta -1)^2 \left(199 \beta ^2+546 \beta +20\right)}{113246208 \pi ^8 \alpha ^5 \beta ^3} \Bigg\} \Bigg\} \, , \\& \rho^{{\langle\bar qGq\rangle}}_{6a}(s) = {m_c{\langle g_s\bar q\sigma Gq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \times \frac{(1 - \alpha - \beta) (110 \alpha +110 \beta +243)}{262144 \pi ^6 \alpha ^2 \beta ^2} \Bigg\} \, , \\& \rho^{{\langle\bar qq\rangle}^2}_{6a}(s)= {{\langle\bar qq\rangle}^2 } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \times \frac{4 \alpha +4 \beta -11}{2048 \pi ^4 \alpha ^2 \beta } \Bigg\} \, , \end{aligned}

    \begin{aligned}[b] &\rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{6a}(s)= {{\langle\bar qq\rangle}{\langle g_s\bar q\sigma Gq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s) \times \frac{28 \alpha ^2+\alpha (168 \beta +67)+8 \beta (11-4 \beta )}{98304 \pi ^4 \alpha ^2 \beta } \Bigg\} \\ &\quad\quad\quad\;\;\quad\quad+ {{\langle\bar qq\rangle}{\langle g_s\bar q\sigma Gq\rangle} } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ {\cal{H}}(s) \times \frac{301 }{98304 \pi ^4 \alpha } \Bigg\} \, , \\& \rho^{{\langle\bar qGq\rangle}^2}_{6a}(s)= {{\langle g_s\bar q\sigma Gq\rangle}^2 } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta \Bigg\{ \frac{7 \alpha -8 \beta}{98304 \pi ^4 \alpha } \Bigg\} + \frac{342 \alpha ^2-381 \alpha -56}{393216 \pi ^4 \alpha } \Bigg\} \\&\quad\;\;\quad\quad\quad+ {{\langle g_s\bar q\sigma Gq\rangle}^2 } \int^{1}_{0}{\rm d}\alpha \Bigg\{ m_c^2 \delta\left(s - {m_c^2 \over \alpha(1-\alpha)}\right) \times \frac{-133}{393216 \pi ^4 \alpha } \Bigg\} \, , \end{aligned}

    \begin{aligned}[b] & \rho^{{\langle\bar qq\rangle}^3}_{6a}(s)= {m_c{\langle\bar qq\rangle}^3 } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \frac{25 }{1024 \pi ^2} \Bigg\} \, , \\& \rho^{\rm pert}_{6b}(s) = {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^5 \times \frac{5(1 - \alpha - \beta)^3 (\alpha +\beta +2)}{1048576 \pi ^8 \alpha ^4 \beta ^4} \Bigg\} \, , \\& \rho^{{\langle\bar qq\rangle}}_{6b}(s) = {m_c {\langle\bar qq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^3 \times \frac{-(1 - \alpha - \beta)^2 (16 \alpha +16 \beta +5)}{49152 \pi ^6 \alpha ^2 \beta ^3} \Bigg\} \, , \\& \rho^{{\langle GG\rangle}}_{6b}(s) = {{\langle g_s^2GG\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta}\Bigg\{ m_c^2 {\cal{F}}(s)^2 \times \frac{25 (1 - \alpha - \beta)^3 \left(\alpha ^4+\alpha ^3 (\beta +2)+\alpha \beta ^3+\beta ^3 (\beta +2)\right)}{6291456 \pi ^8 \alpha ^4 \beta ^4} \\ &\quad\quad\quad\quad + {\cal{F}}(s)^3 \times \Bigg\{ \frac{(1 - \alpha - \beta) \left(261 \alpha ^3+\alpha ^2 (1799 \beta -738)+\alpha \left(1615 \beta ^2-1117 \beta +516\right)\right)}{113246208 \pi ^8 \alpha ^3 \beta ^3} \\ & \quad\quad\quad\quad + \frac{(1 - \alpha - \beta) \left(77 \beta ^3+761 \beta ^2-799 \beta -39\right)}{113246208 \pi ^8 \alpha ^3 \beta ^3} \Bigg\} \Bigg\} \, , \end{aligned}

    \begin{aligned}[b] &\rho^{{\langle\bar qGq\rangle}}_{6b}(s) = {m_c{\langle g_s\bar q\sigma Gq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \; \frac{ (1 - \alpha - \beta) \left(472 \alpha ^2+\alpha (488 \beta -68)+16 \beta ^2-11 \beta -5\right)}{786432 \pi ^6 \alpha ^2 \beta ^2} \Bigg\} , \\& \rho^{{\langle\bar qq\rangle}^2}_{6b}(s)= {{\langle\bar qq\rangle}^2 } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \times \frac{-20 \alpha -20 \beta -45}{8192 \pi ^4 \alpha \beta } \Bigg\} \, , \\& \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{6b}(s)= {{\langle\bar qq\rangle}{\langle g_s\bar q\sigma Gq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s) \times \frac{- 24 \alpha ^2 - \alpha (224 \beta +9) + 12 \beta (2 \beta +7)}{98304 \pi ^4 \alpha \beta } \Bigg\} \\ &\quad\quad\;\;\quad\quad\quad+ {{\langle\bar qq\rangle}{\langle g_s\bar q\sigma Gq\rangle} } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ {\cal{H}}(s) \times \frac{743 }{98304 \pi ^4} \Bigg\} \, , \\ & \rho^{{\langle\bar qGq\rangle}^2}_{6b}(s)={{\langle g_s\bar q\sigma Gq\rangle}^2 } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta \Bigg\{ \frac{ (\beta -\alpha )}{16384 \pi ^4} \Bigg\} + \frac{602 \alpha ^2-461 \alpha -108}{393216 \pi ^4} \Bigg\} \end{aligned}

    \begin{aligned}[b] &\quad\quad\quad\quad+ {{\langle g_s\bar q\sigma Gq\rangle}^2 } \int^{1}_{0}{\rm d}\alpha \Bigg\{ m_c^2 \delta\left(s - {m_c^2 \over \alpha(1-\alpha)}\right) \times \frac{-353}{393216 \pi ^4} \Bigg\} \, , \\ &\rho^{{\langle\bar qq\rangle}^3}_{6b}(s)= {m_c{\langle\bar qq\rangle}^3 } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \frac{35 \alpha }{9216 \pi ^2} \Bigg\} \, . \end{aligned}

    The spectral density \rho_{7}(s) extracted for the current J_{7} is

    \begin{aligned}[b] \rho_{7}(s) =& m_c \left( \rho^{\rm pert}_{7a}(s) + \rho^{{\langle\bar qq\rangle}}_{7a}(s) + \rho^{{\langle GG\rangle}}_{7a}(s)+ \rho^{{\langle\bar qGq\rangle}}_{7a}(s) + \rho^{{\langle\bar qq\rangle}^2}_{7a}(s) + \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{7a}(s)+ \rho^{{\langle\bar qGq\rangle}^2}_{7a}(s) + \rho^{{\langle\bar qq\rangle}^3}_{7a}(s) \right) \\ &+ \not q \; \; \left( \rho^{\rm pert}_{7b}(s) + \rho^{{\langle\bar qq\rangle}}_{7b}(s) + \rho^{{\langle GG\rangle}}_{7b}(s)+ \rho^{{\langle\bar qGq\rangle}}_{7b}(s) + \rho^{{\langle\bar qq\rangle}^2}_{7b}(s) + \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{7b}(s)+ \rho^{{\langle\bar qGq\rangle}^2}_{7b}(s) + \rho^{{\langle\bar qq\rangle}^3}_{7b}(s) \right) \, , \end{aligned}\tag{A7}

    where

    \begin{aligned}[b] \rho^{\rm pert}_{7a}(s) =& {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^5 \times \frac{7 (1 - \alpha - \beta)^3 \left(3 \alpha ^2+2 \alpha (3 \beta +7)+3 \beta ^2+14 \beta +33\right)}{88473600 \pi ^8 \alpha ^5 \beta ^4} \Bigg\} \, , \\ \rho^{{\langle\bar qq\rangle}}_{7a}(s) =& {m_c {\langle\bar qq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^3 \times \frac{-(1 - \alpha - \beta)^2 (10 \alpha +10 \beta +23)}{73728 \pi ^6 \alpha ^3 \beta ^3} \Bigg\} \, , \end{aligned}

    \begin{aligned}[b] \rho^{{\langle GG\rangle}}_{7a}(s) =& {{\langle g_s^2GG\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta}\Bigg\{m_c^2 {\cal{F}}(s)^2 \times \Bigg\{ \frac{7(1 - \alpha - \beta)^3 \left(3 \alpha ^5+2 \alpha ^4 (3 \beta +7)+\alpha ^3 \left(3 \beta ^2+14 \beta +33\right)+3 \alpha ^2 \beta ^3\right)}{106168320 \pi ^8 \alpha ^5 \beta ^4} \\ & + \frac{7(1 - \alpha - \beta)^3 \left(2 \alpha \beta ^3 (3 \beta +7)+\beta ^3 \left(3 \beta ^2+14 \beta +33\right)\right)}{106168320 \pi ^8 \alpha ^5 \beta ^4} \Bigg\} \\ &+ {\cal{F}}(s)^3 \times \Bigg\{ \frac{(\alpha +\beta -1) \left(252 \alpha ^5-\alpha ^4 (324 \beta +1273)-\alpha ^3 \left(2136 \beta ^2+3771 \beta +3733\right)\right)}{1274019840 \pi ^8 \alpha ^5 \beta ^3} \\ & + \frac{(\alpha +\beta -1) \left(\alpha ^2 \left(2544 \beta ^3+5595 \beta ^2+818 \beta -4817\right)-84 (\beta -1)^2 \beta \left(3 \beta ^2+14 \beta +33\right)\right)}{1274019840 \pi ^8 \alpha ^5 \beta ^3} \\ & + \frac{(\alpha +\beta -1) \left(-\alpha \left(1236 \beta ^4+3769 \beta ^3+1717 \beta ^2-6785 \beta +63\right)\right)}{1274019840 \pi ^8 \alpha ^5 \beta ^3} \Bigg\} \Bigg\} \, , \end{aligned}

    \begin{aligned}[b] \rho^{{\langle\bar qGq\rangle}}_{7a}(s) =& {m_c{\langle g_s\bar q\sigma Gq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \times \frac{-530 \alpha ^3 - 105 \alpha ^2 (10 \beta +1) - 102 \alpha \left(5 \beta ^2+\beta -6\right) + (\beta -1)^2 (10 \beta +23)}{1769472 \pi ^6 \alpha ^3 \beta ^2} \Bigg\} \, , \\ \rho^{{\langle\bar qq\rangle}^2}_{7a}(s)=& {{\langle\bar qq\rangle}^2 } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \times \frac{- 10 \alpha - 10 \beta - 1}{3072 \pi ^4 \alpha ^2 \beta } \Bigg\} \, , \end{aligned}

    \begin{aligned}[b] & \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{7a}(s)= {{\langle\bar qq\rangle}{\langle g_s\bar q\sigma Gq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s) \times \frac{ 10 \alpha ^2-140 \alpha \beta +\alpha +3 \beta (10 \beta +1) }{55296 \pi ^4 \alpha ^2 \beta } \Bigg\} \\ &\quad\;\quad\quad\quad\quad+{{\langle\bar qq\rangle}{\langle g_s\bar q\sigma Gq\rangle} } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ {\cal{H}}(s) \times \frac{11 }{3072 \pi ^4 \alpha } \Bigg\} \, , \\& \rho^{{\langle\bar qGq\rangle}^2}_{7a}(s)={{\langle g_s\bar q\sigma Gq\rangle}^2 } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta \Bigg\{ \frac{5 \alpha + 15 \beta}{110592 \pi ^4 \alpha } \Bigg\} + \frac{108 \alpha ^2-86 \alpha -33}{221184 \pi ^4 \alpha } \Bigg\} \\ &\quad\quad\;\;\quad\quad+ {{\langle g_s\bar q\sigma Gq\rangle}^2 } \int^{1}_{0}{\rm d}\alpha \Bigg\{ m_c^2 \delta\left(s - {m_c^2 \over \alpha(1-\alpha)}\right) \times \frac{-11}{24576 \pi ^4 \alpha } \Bigg\} \, , \end{aligned}

    \begin{aligned}[b] & \rho^{{\langle\bar qq\rangle}^3}_{7a}(s)= {m_c{\langle\bar qq\rangle}^3 } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \frac{7 }{864 \pi ^2} \Bigg\} \, , \\ & \rho^{\rm pert}_{7b}(s) = {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^5 \times \frac{7 (1 - \alpha - \beta)^3 \left(6 \alpha ^2+\alpha (12 \beta +13)+6 \beta ^2+13 \beta +21\right)}{58982400 \pi ^8 \alpha ^4 \beta ^4} \Bigg\} \, , \\ &\rho^{{\langle\bar qq\rangle}}_{7b}(s) = {m_c {\langle\bar qq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^3 \times \frac{- (1 - \alpha - \beta)^2 (13 \alpha +13 \beta +20)}{73728 \pi ^6 \alpha ^2 \beta ^3} \Bigg\} \, , \\& \rho^{{\langle\bar qq\rangle}^2}_{7b}(s)= {{\langle\bar qq\rangle}^2 } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \times \frac{- 13 \alpha - 13 \beta + 2}{3072 \pi ^4 \alpha \beta } \Bigg\} \, , \\& \rho^{{\langle\bar qq\rangle}^3}_{7b}(s)= {m_c{\langle\bar qq\rangle}^3 } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \frac{35 \alpha}{5184 \pi ^2} \Bigg\} \, . \end{aligned}

    However, \rho^{{\langle GG\rangle}}_{7b}(s) , \rho^{{\langle\bar qGq\rangle}}_{7b}(s) , \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{7b}(s) , and \rho^{{\langle\bar qGq\rangle}^2}_{7b}(s) are too complicated for extraction.

    There are two different terms, A \equiv [\bar c_a \gamma_\mu c_a]N and B \equiv [\bar c_a \sigma_{\mu\nu} c_a]N , both of which can contribute to the decay of |\bar D \Sigma_c^{*}; 3/2^- \rangle into J/\psi p . Their relevant effective Lagrangians are

    {\cal{L}}^A_{\psi p} = g_A\; \bar P_c^\alpha \left( t_1 g_{\alpha\mu} + t_2 \sigma_{\alpha\mu} \right) N\; \psi^\mu \, , \tag{B1}

    {\cal{L}}^B_{\psi p} = g_B\; \bar P_c^\alpha \left( t_3 g_{\alpha\mu}\gamma_\nu + t_4 \epsilon_{\alpha\mu\nu\rho} \gamma^\rho \gamma_5 \right) N\; \partial^\mu\psi^\nu \, , \tag{B2}

    where t_i are free parameters. The two terms A and B can also contribute to the decays of |\bar D^{*} \Sigma_c; 1/2^- \rangle and |\bar D^{*} \Sigma_c^{*}; 1/2^- \rangle into J/\psi p . Now, the two effective Lagrangians are

    {\cal{L}}^C_{\psi p} = g_C\; \bar P_c \gamma_\mu \gamma_5 N\; \psi^\mu \, ,\tag{B3}

    {\cal{L}}^D_{\psi p}= g_D\; \bar P_c \sigma_{\mu\nu} \gamma_5 N\; \partial^\mu\psi^\nu \, . \tag{B4}

    There are two different terms, C \equiv [\bar c_a \gamma_5 c_a]N and D \equiv [\bar c_a \gamma_\mu \gamma_5 c_a]N , both of which can contribute to the decays of |\bar D \Sigma_c; 1/2^- \rangle , |\bar D^{*} \Sigma_c; 1/2^- \rangle , and |\bar D^{*} \Sigma_c^{*}; 1/2^- \rangle into \eta_c p . Their relevant effective Lagrangians are

    {\cal{L}}^E_{\eta_c p}=g_E\; \bar P_c N\; \eta_c \, , \tag{B5}

    {\cal{L}}^F_{\eta_c p} = g_F\; \bar P_c \gamma_\mu N\; \partial^\mu\eta_c \, . \tag{B6}

    There may be phase angles between g_A/g_B , g_C/g_D , and g_E/g_F , none of which can be well determined in the present study. In this appendix, we rotate these phase angles and redo all calculations. Their relevant (theoretical) uncertainties are summarized in Table B1.

    Table B1

    Table B1.  Relative branching ratios of the \bar D^{(*)} \Sigma_c^{(*)} hadronic molecular states and their relative production rates in \Lambda_b^0 decays. See the caption of Table 3 for detailed explanations. In this table, we consider the (theoretical) uncertainties due to the phase angles between g_A/g_B , g_C/g_D , and g_E/g_F .
    ConfigurationDecay channelsProductions
    J/\psi p\eta_c p\chi_{c0} p\chi_{c1} ph_c p\bar D^{0} \Lambda_c^+\bar D^{*0} \Lambda_c^+\bar D^{0} \Sigma_c^+D^{-} \Sigma_c^{++}\bar D^{*0} \Sigma_c^+D^{*-} \Sigma_c^{++}{\cal{R}}_1{\cal{R}}_2
    |\bar D \Sigma_c; 1/2^- \rangle10.53.80.69t8.22.0-5.0
    |\bar D^{*} \Sigma_c; 1/2^- \rangle0.91.60.33.10.01610^{-4}3.4t1.2t0.12t0.23t1.20.20.4
    |\bar D^{*} \Sigma_c; 3/2^- \rangle10.0050.34t10^{-5}t10^{-5}t\bf1\bf1
    |\bar D \Sigma_c^*; 3/2^- \rangle17100.70250t
    |\bar D^* \Sigma_c^*; 1/2^- \rangle1253310.300.100.0234t1.5t0.15t0.30t0.35t0.70t4.80.12.4
    |\bar D^* \Sigma_c^*; 3/2^- \rangle10.0060.0080.39t10^{-5}t10^{-4}t0.04t0.08t0.180.16
    |\bar D^* \Sigma_c^*; 5/2^- \rangle
    DownLoad: CSV
    Show Table

    In this paper, we intend to interpret P_c(4440)^+ and P_c(4457)^+ as the \bar D^* \Sigma_c molecular states of J^P = 3/2^- and 1/2^- , respectively. However, they can also be interpreted as the \bar D^* \Sigma_c molecular states of J^P = 1/2^- and 3/2^- , respectively. Based on the latter interpretations, we assume the masses of the \bar D^{(*)} \Sigma_c^{(*)} molecular states to be

    \begin{aligned}[b] M_{|\bar D \Sigma_c; 1/2^- \rangle} =& M_{P_c(4312)^+} = 4311.9\; {\rm{MeV}} \, , \\ M_{|\bar D^{*} \Sigma_c; 1/2^- \rangle} =& M_{P_c(4440)^+} = 4440.3\; {\rm{MeV}} \, , \\ M_{|\bar D^{*} \Sigma_c; 3/2^- \rangle} =& M_{P_c(4457)^+} = 4457.3\; {\rm{MeV}} \, , \end{aligned}

    \begin{aligned}[b] M_{|\bar D \Sigma_c^{*}; 3/2^- \rangle} \approx& M_{D} + M_{\Sigma_c^*} = 4385\; {\rm{MeV}} \, , \\ M_{|\bar D^{*} \Sigma_c^*; 1/2^- \rangle} \approx& M_{D^*} + M_{\Sigma_c^*} = 4527\; {\rm{MeV}} \, , \\ M_{|\bar D^{*} \Sigma_c^*; 3/2^- \rangle} \approx& M_{D^*} + M_{\Sigma_c^*} = 4527\; {\rm{MeV}} \, , \\ M_{|\bar D^{*} \Sigma_c^*; 5/2^- \rangle} \approx& M_{D^*} + M_{\Sigma_c^*} = 4527\; {\rm{MeV}} \, , \end{aligned}\tag{C1}

    and redo all calculations. We summarize the obtained results in Table C1. Even when considering the uncertainty on {\cal{R}}_2 to be at the X^{+300\%}_{-\; 75\%} level, these results do not appear to easily explain the relative contributions {\cal{R}} \equiv {\cal{B}}(\Lambda^0_b \to P_c^+ K^-){\cal{B}}(P_c^+ \to J/\psi p)/{\cal{B}}(\Lambda^0_b \to J/\psi p K^-) measured by the LHCb experiment [5], as given in Eqs. (129).

    Table C1

    Table C1.  Relative branching ratios of the \bar D^{(*)} \Sigma_c^{(*)} hadronic molecular states and their relative production rates in \Lambda_b^0 decays. See the caption of Table 3 for detailed explanations. In this table, we work under the assumption that P_c(4440)^+ and P_c(4457)^+ are interpreted as the \bar D^* \Sigma_c molecular states of J^P = 1/2^- and 3/2^- , respectively.
    ConfigurationDecay channelsProductions
    J/\psi p\eta_c p\chi_{c0} p\chi_{c1} ph_c p\bar D^{0} \Lambda_c^+\bar D^{*0} \Lambda_c^+\bar D^{0} \Sigma_c^+D^{-} \Sigma_c^{++}\bar D^{*0} \Sigma_c^+D^{*-} \Sigma_c^{++}{\cal{R}}_1{\cal{R}}_2
    |\bar D \Sigma_c; 1/2^- \rangle13.80.69t8.62.1
    |\bar D^{*} \Sigma_c; 1/2^- \rangle10.360.0133.4t1.2t0.11t0.22t1.30.28
    |\bar D^{*} \Sigma_c; 3/2^- \rangle10.00510^{-4}0.35t10^{-5}t10^{-5}t\bf1\bf1
    |\bar D \Sigma_c^*; 3/2^- \rangle10.70250t
    |\bar D^* \Sigma_c^*; 1/2^- \rangle1310.300.100.0234t1.5t0.15t0.30t0.35t0.70t5.00.10
    |\bar D^* \Sigma_c^*; 3/2^- \rangle10.0060.0080.39t10^{-5}t10^{-4}t0.04t0.08t0.190.17
    |\bar D^* \Sigma_c^*; 5/2^- \rangle
    DownLoad: CSV
    Show Table
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3. Wu, Q., Chen, D.-Y. Production of Pψs Λ (4338) from Ξb decay[J]. Physical Review D, 2024, 109(9): 094003. doi: 10.1103/PhysRevD.109.094003
4. Wang, F.-L., Liu, X. Surveying the mass spectra and the electromagnetic properties of the Ξc (′,∗) D (∗) molecular pentaquarks[J]. Physical Review D, 2024, 109(1): 014043. doi: 10.1103/PhysRevD.109.014043
5. Lin, J.-X., Chen, H.-X., Liang, W.-H. et al. Molecular pentaquark states with open charm and bottom flavors[J]. European Physical Journal A, 2024, 60(1): 15. doi: 10.1140/epja/s10050-024-01240-7
6. Özdem, U.. Electromagnetic properties of D¯(⁎)Ξc′, D¯(⁎)Λc, D¯s(⁎)Λc and D¯s(⁎)Ξc pentaquarks[J]. Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, 2023. doi: 10.1016/j.physletb.2023.138267
7. Azizi, K., Sarac, Y., Sundu, H. Investigation of the strange pentaquark candidate Pψs Λ (4338)0 recently observed by LHCb[J]. Physical Review D, 2023, 108(7): 074010. doi: 10.1103/PhysRevD.108.074010
8. Wang, F.-L., Liu, X. Higher molecular Pψs Λ/ ς pentaquarks arising from the Ξc (′,∗) D ¯ 1/ Ξc (′,∗) D ¯ 2∗ interactions[J]. Physical Review D, 2023, 108(5): 054028. doi: 10.1103/PhysRevD.108.054028
9. Xin, Q., Yang, X.-S., Wang, Z.-G. The singly charmed pentaquark molecular states via the QCD sum rules[J]. International Journal of Modern Physics A, 2023, 38(22-23): 2350123. doi: 10.1142/S0217751X23501233
10. Wang, F.-L., Luo, S.-Q., Zhou, H.-Y. et al. Exploring the electromagnetic properties of the Ξc (′,∗) D ¯ s∗ and ωc (∗) D ¯ s∗ molecular states[J]. Physical Review D, 2023, 108(3): 034006. doi: 10.1103/PhysRevD.108.034006
11. Huang, H., Deng, C., Liu, X. et al. Tetraquarks and Pentaquarks from Quark Model Perspective[J]. Symmetry, 2023, 15(7): 1298. doi: 10.3390/sym15071298
12. Meng, L., Wang, B., Wang, G.-J. et al. Chiral perturbation theory for heavy hadrons and chiral effective field theory for heavy hadronic molecules[J]. Physics Reports, 2023. doi: 10.1016/j.physrep.2023.04.003
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Hua-Xing Chen. Hidden-charm pentaquark states through the current algebra: From their productions to decays[J]. Chinese Physics C. doi: 10.1088/1674-1137/ac6ed2
Hua-Xing Chen. Hidden-charm pentaquark states through the current algebra: From their productions to decays[J]. Chinese Physics C.  doi: 10.1088/1674-1137/ac6ed2 shu
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Hidden-charm pentaquark states through current algebra: from their production to decay

  • School of Physics, Southeast University, Nanjing 210094, China

Abstract: There may be seven \bar D^{(*)} \Sigma_c^{(*)} hadronic molecular states. We construct their corresponding interpolating currents and calculate their masses and decay constants using QCD sum rules. Based on these results, we calculate their relative production rates in \Lambda_b^0 decays using current algebra, that is, {\cal{B}}(\Lambda_b^0 \to P_c K^-):{\cal{B}}(\Lambda_b^0 \to P_c^\prime K^-) , where P_c and P_c^\prime are two different states. We also study their decay properties via Fierz rearrangement and further calculate these ratios in the J/\psi p mass spectrum, that is, {\cal{B}}(\Lambda_b^0 \to P_c K^- \to J/\psi p K^-):{\cal{B}}(\Lambda_b^0 \to P_c^\prime K^- \to J/\psi p K^-) . Our results suggest that the \bar D^{*} \Sigma_c^{*} molecular states of J^P = 1/2^- and 3/2^- may be observed in future experiments.

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    I.   INTRODUCTION
    • Since the discovery of X(3872) by Belle in 2003 [1], many charmonium-like XYZ states have been discovered [2]. Some of these structures may contain four quarks, \bar c c \bar q q ( q=u/d ), and are therefore good candidates for hidden-charm tetraquark states.

      In recent years, the LHCb Collaboration has continuously observed as many as five interesting exotic structures:

      ● In 2015, the LHCb experiment observed two structures, P_c(4380)^+ and P_c(4450)^+ , in the J/\psi p invariant mass spectrum of the \Lambda_b^0\to J/\psi p K^- decays [3]:

      \begin{aligned}[b] P_c(4380)^+: M=& 4380 \pm 8 \pm 29 \rm{ MeV} \, ,\\ \Gamma=& 205 \pm 18 \pm 86 \rm{ MeV} \, , \end{aligned}

      (1)

      \begin{aligned}[b] P_c(4450)^+: M=& 4449.8 \pm 1.7 \pm 2.5 \rm{ MeV} \, , \\ \Gamma=& 39 \pm 5 \pm 19 \rm{ MeV} \, . \end{aligned}

      (2)

      This observation was later supported by a subsequent LHCb experiment investigating the J/\psi p invariant mass spectrum of the \Lambda_b^0\to J/\psi p \pi^- decays [4].

      ● In 2019, the LHCb experiment observed a new structure, P_c(4312)^+ , and further separated P_c(4450)^+ into two substructures, P_c(4440)^+ and P_c(4457)^+ , again in the J/\psi p invariant mass spectrum of the \Lambda_b^0\to J/\psi p K^- decays [5].

      \begin{aligned}[b] P_c(4312)^+: M=& 4311.9 \pm 0.7 ^{+6.8}_{-0.6} \rm{ MeV} \, , \\ \Gamma=& 9.8 \pm 2.7 ^{+3.7}_{-4.5} \rm{ MeV} \, , \end{aligned}

      (3)

      \begin{aligned}[b] P_c(4440)^+: M=& 4440.3 \pm 1.3 ^{+4.1}_{-4.7} \rm{ MeV} \, ,\\ \Gamma=& 20.6 \pm 4.9 ^{+8.7}_{-10.1} \rm{ MeV} \, , \end{aligned}

      (4)

      \begin{aligned}[b] P_c(4457)^+: M=& 4457.3 \pm 0.6 ^{+4.1}_{-1.7} \rm{ MeV} \, ,\\ \Gamma=& 6.4 \pm 2.0 ^{+5.7}_{-1.9} \rm{ MeV} \, .\\ \end{aligned}

      (5)

      ● In 2020, the LHCb experiment reported evidence of a hidden-charm pentaquark state with strangeness, P_{cs}(4459)^0 , in the J/\psi \Lambda invariant mass spectrum of the \Xi_b^- \to J/\psi \Lambda K^- decays [6].

      \begin{aligned}[b] P_{cs}(4459)^0: M=& 4458.8 \pm 2.9^{+4.7}_{-1.1} \rm{ MeV} \, , \\ \Gamma=& 17.3 \pm 6.5^{+8.0}_{-5.7} \rm{ MeV} \, . \end{aligned}

      (6)

      These structures contain at least five quarks, \bar c c u u d or \bar c c u d s ; therefore, they are perfect candidates for hidden-charm pentaquark states. The charmonium-like XYZ and hidden-charm pentaquark states have attracted significant attention, and studies on these states have greatly improved our understanding of the non-perturbative behaviors of the strong interaction in the low energy region [718].

      To understand the P_c and P_{cs} states, various theoretical interpretations have been proposed, such as loosely-bound hadronic molecular states [1940], tightly-bound compact pentaquark states [4151], and kinematical effects [5255]. In particular, the three narrow states P_c(4312)^+ , P_c(4440)^+ , and P_c(4457)^+ are just below the \bar D \Sigma_c and \bar D^{*} \Sigma_c thresholds; therefore, it is natural to describe them as \bar D^{(*)} \Sigma_c hadronic molecular states, whose existence was predicted in Refs. [5660] before the 2015 LHCb experiment [3]. The other narrow state, P_{cs}(4459)^0 , is just below the \bar D^{*} \Xi_c threshold; hence, it is natural to describe it as the \bar D^{*} \Xi_c molecular state [61, 62].

      However, these exotic structures were only observed in the LHCb experiment [36]. It is crucial to search for their partner states as well as other potential decay channels to further understand their nature. There have been several theoretical studies on this subject using, for example, effective approaches [6366], the quark interchange model [67, 68], heavy quark symmetry [69, 70], and QCD sum rules [71]. We refer to reviews [718] and the references therein for detailed discussions.

      In this paper, we systematically investigate hidden-charm pentaquark states as \bar D^{(*)} \Sigma_c^{(*)} hadronic molecular states through their corresponding hidden-charm pentaquark interpolating currents. We systemically construct all the relevant currents and apply QCD sum rules to calculate their masses and decay constants. The obtained results are used to further study their production and decay properties.

      Our strategy is fairly straightforward. First, we construct a hidden-charm pentaquark current, such as

      \begin{aligned}[b] \sqrt2 \xi_1(x) =& [\delta^{ab} \bar c_a(x) \gamma_5 d_b(x)] \\ & \times [\epsilon^{cde} u_c^T(x) \mathbb{C} \gamma_\mu u_d(x) \gamma^\mu \gamma_5 c_e(x)] \, , \end{aligned}

      (7)

      where a \cdots e are color indices. This is the best coupling of the current to the D^- \Sigma_c^{++} molecular state of J^P = 1/2^- through

      \langle 0 | \xi_1 | D^- \Sigma_c^{++}; 1/2^-(q) \rangle = f_1 u(q) \, ,

      (8)

      where u(q) is the Dirac spinor of | D^- \Sigma_c^{++}; 1/2^- \rangle . Its decay constant f_1 can be calculated using QCD sum rules.

      Second, we investigate three-body \Lambda_b^0 \to J/\psi p K^- decays. The total quark content of the final states is udc \bar c s \bar u u , where the intermediate states D^{(*)-} \Sigma_c^{(*)++} K^- can be produced. We apply Fierz rearrangement to carefully examine the combination of these seven quarks, from which we select the current \xi_1 and evaluate the relative production rate of | D^- \Sigma_c^{++}; 1/2^- \rangle .

      Third, we apply the Fierz rearrangement of the Dirac and color indices to transform the current \xi_1 into

      \sqrt2 \xi_1 \rightarrow {1\over6} \; [\bar c_a \gamma_5 c_a]\; N - {1\over12} \; [\bar c_a \gamma_\mu c_a]\; \gamma^\mu \gamma_5 N + \cdots \, ,

      (9)

      where N = \epsilon^{abc} (u_a^T \mathbb{C} d_b) \gamma_5 u_c - \epsilon^{abc} (u_a^T \mathbb{C} \gamma_5 d_b) u_c is Ioffe's light baryon field coupling to a proton [7274]. Accordingly, \xi_1 couples to the \eta_c p and J/\psi p channels simultaneously:

      \begin{aligned}[b] \langle 0 | \xi_1 | \eta_c p \rangle \approx& {\sqrt2\over12} \langle 0 | \bar c_{a} \gamma_5 c_a | \eta_c \rangle\; \langle 0 | N | p \rangle + \cdots \, , \\ \langle 0 | \xi_1 | \psi p \rangle \approx & -{\sqrt2\over24} \langle 0 | \bar c_{a} \gamma_\mu c_a | \psi \rangle\; \gamma^\mu \gamma_5 \langle 0 | N | p \rangle + \cdots \, . \end{aligned}

      (10)

      We can use these two equations to straightforwardly calculate the relative branching ratio of the | D^- \Sigma_c^{++}; 1/2^- \rangle decay into \eta_c p to its decay into J/\psi p [75]. We refer to Ref. [76] for detailed discussions. There, we applied the same method to study the decay properties of P_c(4312)^+ , P_c(4440)^+ , and P_c(4457)^+ as \bar D^{(*)} \Sigma_c molecular states, and in this paper, we apply it to study the decay properties of the \bar D^{(*)} \Sigma_c^* molecular states.

      This paper is organized as follows. In Sec. II, we systematically construct the hidden-charm pentaquark currents corresponding to the \bar D^{(*)} \Sigma_c^{(*)} hadronic molecular states. We use them to perform QCD sum rule analyses in Sec. III and calculate their masses and decay constants. The obtained results are used in Sec. IV to study their production in \Lambda_b^0 decays using current algebra. In Sec. V, we use the Fierz rearrangement of the Dirac and color indices to study the decay properties of the \bar D^{(*)} \Sigma_c^{*} molecular states and calculate several of their relative branching ratios. The obtained results are summarized and discussed in Sec. VI.

    II.   HIDDEN-CHARM PENTAQUARK INTERPOLATING CURRENTS
    • In this section, we use the \bar c , c, u, u, and d ( q=u/d ) quarks to construct hidden-charm pentaquark interpolating currents. We consider the following three types of currents:

      \begin{aligned}[b] \theta(x) =& [\bar c_a(x) \Gamma^\theta_1 c_b(x)] \; \Big[[q^T_c(x) \mathbb{C} \Gamma^\theta_2 q_d(x)] \; \Gamma^\theta_3 q_e(x)\Big] \, , \\ \eta(x) =& [\bar c_a(x) \Gamma^\eta_1 u_b(x)] \; \Big[[u^T_c(x) \mathbb{C} \Gamma^\eta_2 d_d(x)] \; \Gamma^\eta_3 c_e(x) \Big] \, ,\\ \xi(x) =& [\bar c_a(x) \Gamma^\xi_1 d_b(x)] \; \Big[[u^T_c(x) \mathbb{C} \Gamma^\xi_2 u_d(x)] \; \Gamma^\xi_3 c_e(x) \Big] \, , \end{aligned}

      (11)

      where a \cdots e are color indices, \Gamma_{1/2/3}^{\theta/\eta/\xi} are Dirac matrices, and \mathbb{C} = {\rm i}\gamma_2 \gamma_0 is the charge-conjugation operator. We illustrate these in Fig. 1. These three configurations can be related using Fierz rearrangement in Lorentz space and color rearrangement.

      Figure 1.  (color online) Three types of hidden-charm pentaquark interpolating currents, \theta(x), \eta(x), and \xi(x). Quarks are shown in red/green/blue, and antiquarks are shown in cyan/magenta/yellow. Taken from Ref. [76].

      \delta^{ab} \epsilon^{cde} = \delta^{ac} \epsilon^{bde} + \delta^{ad} \epsilon^{cbe} + \delta^{ae} \epsilon^{cdb} \, .

      (12)

      This is discussed in detail in Sec. V, where we construct the \theta(x) currents by combining charmonium operators and light baryon fields.

      In this section, we construct the \eta(x) and \xi(x) currents and use them to construct currents corresponding to the \bar D^{(*)} \Sigma_c^{(*)} hadronic molecular states. To achieve this, we combine charmed meson operators and charmed baryon fields. There are five independent charmed meson operators:

      \begin{aligned}[b]& \quad\quad\quad\quad\quad \bar c_a q_a \, [0^+] \, , \quad \, \bar c_a \gamma_5 q_a \, [0^-] \, ,\quad\\&\bar c_a \gamma_\mu q_a \, [1^-] \, ,\quad \, \bar c_a \gamma_\mu \gamma_5 q_a \, [1^+] \, , \,\quad \bar c_a \sigma_{\mu\nu} q_a \, [1^\pm] \, .\end{aligned}

      (13)

      There is another, \bar c_d \sigma_{\mu\nu} \gamma_5 q_d ; however, it is related to \bar c_d \sigma_{\mu\nu} q_d through

      \sigma_{\mu\nu} \gamma_5 = {{\rm i}\over2} \epsilon_{\mu\nu\rho\sigma} \sigma^{\rho\sigma} \, .

      (14)

      In particular, we require the J^P = 0^- and 1^- operators to construct the \eta(x) and \xi(x) currents, which couple to the ground-state charmed mesons {\cal{D}} = D/D^{*} .

      J_{D} = \bar c_a \gamma_5 q_a \, , \quad J_{D^{*}} = \bar c_a \gamma_\mu q_a \, .

      (15)

      Charmed baryon fields have been systematically constructed and studied in Refs. [7780] using the method of QCD sum rules [81, 82] within heavy quark effective theory [8385]. In this paper, we require the following charmed baryon fields, J_{{\cal{B}}} , which couple to the ground-state charmed baryons {\cal{B}} = \Lambda_c/\Sigma_c/\Sigma_c^{*} :

      \begin{aligned}[b] J_{\Lambda_c^+} =& \epsilon^{abc} [u_a^T \mathbb{C} \gamma_{5} d_b] c_c \, , \\ \sqrt2 J_{\Sigma_c^{++}} =& \epsilon^{abc} [u_a^T \mathbb{C} \gamma_{\mu} u_b] \gamma^{\mu}\gamma_{5} c_c \, , \\ J_{\Sigma_c^+} =& \epsilon^{abc} [u_a^T \mathbb{C} \gamma_{\mu} d_b] \gamma^{\mu}\gamma_{5} c_c \, , \\ \sqrt2 J_{\Sigma_c^{0}} =& \epsilon^{abc} [d_a^T \mathbb{C} \gamma_{\mu} d_b] \gamma^{\mu}\gamma_{5} c_c \, , \\ \sqrt2 J^\alpha_{\Sigma_c^{*++}} =& \epsilon^{abc} P_{3/2}^{\alpha\mu} [u_a^T \mathbb{C} \gamma_{\mu} u_b] c_c \, , \\ J^\alpha_{\Sigma_c^{*+}} =& \epsilon^{abc} P_{3/2}^{\alpha\mu} [u_a^T \mathbb{C} \gamma_{\mu} d_b] c_c \, , \\ \sqrt2 J^\alpha_{\Sigma_c^{*0}} =& \epsilon^{abc} P_{3/2}^{\alpha\mu} [d_a^T \mathbb{C} \gamma_{\mu} d_b] c_c \, . \end{aligned}

      (16)

      Here, P_{3/2}^{\mu\nu} is the spin-3/2 projection operator

      P_{3/2}^{\mu\nu} = g^{\mu\nu} - {1 \over 4} \gamma^\mu\gamma^\nu \, .

      (17)

      In the molecular picture, P_c(4312)^+ , P_c(4440)^+ , and P_c(4457)^+ are usually interpreted as the \bar D \Sigma_c and \bar D^* \Sigma_c hadronic molecular states [20, 21, 60]. Their relevant currents have been constructed in Ref. [76]. In this paper, we further construct the \bar D \Sigma_c^{*} and \bar D^* \Sigma_c^{*} currents; they are all summarized here for completeness.

      Altogether, there can be seven \bar D^{(*)} \Sigma_c^{(*)} hadronic molecular states, which are \bar D \Sigma_c of J^P = {1/2}^-, \bar D^* \Sigma_c of J^P = {(1/2)}^-/{(3/2)}^- , \bar D \Sigma_c^* of J^P = {3/2}^-, and \bar D^* \Sigma_c^* of J^P = {(1/2)}^-/{(3/2)}^-/{(5/2)}^-:

      \begin{aligned}[b] | \bar D \Sigma_c; {1/2}^- ; \theta \rangle =& \cos\theta\; | \bar D^0 \Sigma_c^+;1/2^- \rangle\\& + \sin\theta\; | D^- \Sigma_c^{++};1/2^- \rangle \, , \end{aligned}

      (18)

      \begin{aligned}[b] | \bar D^* \Sigma_c; {1/2}^- ; \theta \rangle =& \cos\theta\; | \bar D^{*0} \Sigma_c^+;1/2^- \rangle \\&+ \sin\theta\; | D^{*-} \Sigma_c^{++};1/2^- \rangle \, , \end{aligned}

      (19)

      \begin{aligned}[b] | \bar D^* \Sigma_c; {3/2}^- ; \theta \rangle =& \cos\theta\; | \bar D^{*0} \Sigma_c^+;3/2^- \rangle \\&+ \sin\theta\; | D^{*-} \Sigma_c^{++};3/2^- \rangle \, , \end{aligned}

      (20)

      \begin{aligned}[b] | \bar D \Sigma_c^*; {3/2}^- ; \theta \rangle =& \cos\theta\; | \bar D^{0} \Sigma_c^{*+};3/2^- \rangle \\&+ \sin\theta\; | D^- \Sigma_c^{*++};3/2^- \rangle \, , \end{aligned}

      (21)

      \begin{aligned}[b] | \bar D^* \Sigma_c^*; {1/2}^- ; \theta \rangle =& \cos\theta\; | \bar D^{*0} \Sigma_c^{*+};1/2^- \rangle \\&+ \sin\theta\; | D^{*-} \Sigma_c^{*++};1/2^- \rangle \, ,\end{aligned}

      (22)

      \begin{aligned}[b] | \bar D^* \Sigma_c^*; {3/2}^- ; \theta \rangle =& \cos\theta\; | \bar D^{*0} \Sigma_c^{*+};3/2^- \rangle \\&+ \sin\theta\; | D^{*-} \Sigma_c^{*++};3/2^- \rangle \, , \end{aligned}

      (23)

      \begin{aligned}[b] | \bar D^* \Sigma_c^*; {5/2}^- ; \theta \rangle =& \cos\theta\; | \bar D^{*0} \Sigma_c^{*+};5/2^- \rangle\\& + \sin\theta\; | D^{*-} \Sigma_c^{*++};5/2^- \rangle \, , \end{aligned}

      (24)

      where θ is an isospin parameter satisfying \theta = -55^{\rm{o}} for I=1/2 and \theta = 35^{\rm{o}} for I=3/2 . In the present study, we concentrate on the former I=1/2 states, so that we may simplify the notations to

      \begin{aligned}[b] | \bar D^{(*)} \Sigma_c^{(*)}; J^P \rangle =& {\sqrt{1/3}}\; | \bar D^{(*)0} \Sigma_c^{(*)+}; J^P \rangle \\&- {\sqrt{2/3}}\; | D^{(*)-} \Sigma_c^{(*)++}; J^P \rangle . \end{aligned}

      (25)

      Their relevant interpolating currents are

      J_i = \cos\theta\; \eta_i + \sin\theta\; \xi_i \, ,

      (26)

      where

      \begin{aligned}[b] \eta_1 =& [\delta^{ab} \bar c_a \gamma_5 u_b] \; [\epsilon^{cde} u_c^T \mathbb{C} \gamma_\mu d_d \gamma^\mu \gamma_5 c_e] \\ =& \bar D^0 \; \Sigma_c^+ \, , \end{aligned}

      (27)

      \begin{aligned}[b] \eta_2 =& [\delta^{ab} \bar c_a \gamma_\nu u_b] \; \gamma^\nu \gamma_5 \; [\epsilon^{cde} u_c^T \mathbb{C} \gamma_\mu d_d \gamma^\mu \gamma_5 c_e] \\ =& \bar D^{*0}_\nu \; \gamma^\nu \gamma_5 \; \Sigma_c^+ \, , \end{aligned}

      (28)

      \begin{aligned}[b] \eta_3^\alpha =& P_{3/2}^{\alpha\nu} \; [\delta^{ab} \bar c_a \gamma_\nu u_b] \; [\epsilon^{cde} u_c^T \mathbb{C} \gamma_\mu d_d \gamma^\mu \gamma_5 c_e] \\ =& P_{3/2}^{\alpha\nu} \; \bar D^{*0}_\nu \; \Sigma_c^+ \, , \end{aligned}

      (29)

      \begin{aligned}[b] \eta_4^\alpha =& [\delta^{ab} \bar c_a \gamma_5 u_b] \; P_{3/2}^{\alpha\mu} [\epsilon^{cde} u_c^T \mathbb{C} \gamma_\mu d_d c_e] \\ =& \bar D^0 \; \Sigma_c^{*+;\alpha} \, , \end{aligned}

      (30)

      \begin{aligned}[b] \eta_5 =& [\delta^{ab} \bar c_a \gamma_\nu u_b] \; P_{3/2}^{\nu\mu} [\epsilon^{cde} u_c^T \mathbb{C} \gamma_\mu d_d c_e] \\ =& \bar D^{*0}_\nu \; \Sigma_c^{*+;\nu} \, , \end{aligned}

      (31)

      \begin{aligned}[b] \eta_6^{\alpha} =& [\delta^{ab} \bar c_a \gamma_\nu u_b] \; P_{3/2}^{\alpha\rho} \; \gamma^\nu \gamma_5 \; P^{3/2}_{\rho\mu} [\epsilon^{cde} u_c^T \mathbb{C} \gamma^\mu d_d c_e] \\ =& \bar D^{*0}_\nu \; P_{3/2}^{\alpha\rho} \; \gamma^\nu \gamma_5 \; \Sigma_{c;\rho}^{*+} \, , \end{aligned}

      (32)

      \begin{aligned}[b] \eta_7^{\alpha\beta} =& P^{\alpha\beta,\nu\rho}_{5/2} \; [\delta^{ab} \bar c_a \gamma_\nu u_b] \; P^{3/2}_{\rho\mu} [\epsilon^{cde} u_c^T \mathbb{C} \gamma^\mu d_d c_e] \\ =& P^{\alpha\beta,\nu\rho}_{5/2} \; \bar D^{*0}_\nu \; \Sigma_{c;\rho}^{*+} \, , \end{aligned}

      (33)

      and

      \begin{aligned}[b] \xi_1 =& {1\over\sqrt2} \; [\delta^{ab} \bar c_a \gamma_5 d_b] \; [\epsilon^{cde} u_c^T \mathbb{C} \gamma_\mu u_d \gamma^\mu \gamma_5 c_e] \\ =& D^- \; \Sigma_c^{++} \, , \end{aligned}

      (34)

      \begin{aligned}[b] \xi_2 =& {1\over\sqrt2} \; [\delta^{ab} \bar c_a \gamma_\nu d_b] \; \gamma^\nu \gamma_5 \; [\epsilon^{cde} u_c^T \mathbb{C} \gamma_\mu u_d \gamma^\mu \gamma_5 c_e] \\ =& D^{*-}_\nu \; \gamma^\nu \gamma_5 \; \Sigma_c^{++} \, , \end{aligned}

      (35)

      \begin{aligned}[b] \xi_3^\alpha =& {1\over\sqrt2} \; P_{3/2}^{\alpha\nu} \; [\delta^{ab} \bar c_a \gamma_\nu d_b] \; [\epsilon^{cde} u_c^T \mathbb{C} \gamma_\mu u_d \gamma^\mu \gamma_5 c_e] \\ =& P_{3/2}^{\alpha\nu} \; D^{*-}_\nu \; \Sigma_c^{++} \, , \end{aligned}

      (36)

      \begin{aligned}[b] \xi_4^\alpha =& {1\over\sqrt2} \; [\delta^{ab} \bar c_a \gamma_5 d_b] \; P_{3/2}^{\alpha\mu} [\epsilon^{cde} u_c^T \mathbb{C} \gamma_\mu u_d c_e] \\ =& D^- \; \Sigma_c^{*++;\alpha} \, , \end{aligned}

      (37)

      \begin{aligned}[b] \xi_5 =& {1\over\sqrt2} \; [\delta^{ab} \bar c_a \gamma_\nu d_b] \; P_{3/2}^{\nu\mu} [\epsilon^{cde} u_c^T \mathbb{C} \gamma_\mu u_d c_e] \\ =& D^{*-}_\nu \; \Sigma_c^{*++;\nu} \, , \end{aligned}

      (38)

      \begin{aligned}[b] \xi_6^{\alpha} =& {1\over\sqrt2} \; [\delta^{ab} \bar c_a \gamma_\nu d_b] \; P_{3/2}^{\alpha\rho} \gamma^\nu \gamma_5 \; P^{3/2}_{\rho\mu} [\epsilon^{cde} u_c^T \mathbb{C} \gamma^\mu u_d c_e] \\ =& D^{*-}_\nu \; P_{3/2}^{\alpha\rho} \; \gamma^\nu \gamma_5 \; \Sigma_{c;\rho}^{*++} \, ,\\[-10pt] \end{aligned}

      (39)

      \begin{aligned}[b] \xi_7^{\alpha\beta} =& {1\over\sqrt2} \; P^{\alpha\beta,\nu\rho}_{5/2} \; [\delta^{ab} \bar c_a \gamma_\nu d_b] \; P^{3/2}_{\rho\mu} [\epsilon^{cde} u_c^T \mathbb{C} \gamma^\mu u_d c_e] \\ =& P^{\alpha\beta,\nu\rho}_{5/2} \; D^{*-}_\nu \; \Sigma_{c;\rho}^{*++} \, . \\[-10pt]\end{aligned}

      (40)

      In the above expressions, we use {\cal{D}} and {\cal{B}} to denote the charmed meson operators J_{{\cal{D}}} and charmed baryon fields J_{{\cal{B}}} for simplicity; P_{5/2}^{\mu\nu,\rho\sigma} is the spin-5/2 projection operator

      \begin{aligned}[b] P_{5/2}^{\mu\nu,\rho\sigma} =& {1\over2} g^{\mu\rho} g^{\nu\sigma} + {1\over2} g^{\mu\sigma} g^{\nu\rho} - {1 \over 6} g^{\mu\nu} g^{\rho\sigma} - {1 \over 12} g^{\mu\rho} \gamma^{\nu}\gamma^{\sigma}\\& - {1 \over 12} g^{\mu\sigma} \gamma^{\nu}\gamma^{\rho} - {1 \over 12} g^{\nu\sigma} \gamma^{\mu}\gamma^{\rho} - {1 \over 12} g^{\nu\rho} \gamma^{\mu}\gamma^{\sigma} \, . \end{aligned}

      (41)
    III.   MASSES AND DECAY CONSTANTS THROUGH QCD SUM RULES
    • In this section, we use QCD sum rules [81, 82] to study \bar D^{(*)} \Sigma_c^{(*)} molecular states through the currents J_{1\cdots7} , that is, J_{1,2,5} of J^P = 1/2^- , J^\alpha_{3,4,6} of J^P = 3/2^- , and J_{7}^{\alpha\beta} of J^P = 5/2^- . We calculate their masses and decay constants, and the obtained results are used in the next section to further calculate their relative production rates. Several of these calculations have been performed in Refs. [19, 8688], and we refer to Refs. [3840, 50, 61] for more relevant QCD sum rule studies.

    • A.   Correlation functions

    • We assume that the currents J_{1\cdots7} couple to the \bar D^{(*)} \Sigma_c^{(*)} molecular states X_{1\cdots7} through

      \begin{aligned}[b] \langle 0 | J_{1,2,5} | X_{1,2,5}; 1/2^- \rangle =& f_{X_{1,2,5}} u (p) \, , \\ \langle 0 | J_{3,4,6}^\alpha | X_{3,4,6}; 3/2^- \rangle =& f_{X_{3,4,6}} u^\alpha (p) \, , \\ \langle 0 | J_{7}^{\alpha\beta} | X_{7}; 5/2^- \rangle =& f_{X_7} u^{\alpha\beta} (p) \, , \end{aligned}

      (42)

      where u(p) , u^\alpha(p) , and u^{\alpha\beta}(p) are spinors of X_{1\cdots7} . The two-point correlation functions extracted from these currents can be written as

      \begin{aligned}[b] \Pi_{1,2,5}\left(q^2\right) =& {\rm i} \int {\rm d}^4x {\rm e}^{{\rm i}q\cdot x} \langle 0 | T\left[J_{1,2,5}(x) \bar J_{1,2,5}(0)\right] | 0 \rangle \\ =& (\not q + M_{X_{1,2,5}}) \; \Pi_{1,2,5}\left(q^2\right) \, ,\\[-10pt] \end{aligned}

      (43)

      \begin{aligned}[b] \Pi^{\alpha \alpha^\prime}_{3,4,6}\left(q^2\right) =& {\rm i} \int {\rm d}^4x {\rm e}^{{\rm i}q\cdot x} \langle 0 | T\left[J^{\alpha}_{3,4,6}(x) \bar J^{\alpha^\prime}_{3,4,6}(0)\right] | 0 \rangle \\ =& {\cal{G}}_{3/2}^{\alpha \alpha^\prime} (\not q + M_{X_{3,4,6}})\; \Pi_{3,4,6}\left(q^2\right) \, , \\[-8pt]\end{aligned}

      (44)

      \begin{aligned}[b] \Pi^{\alpha \beta,\alpha^\prime \beta^\prime}_7\left(q^2\right) =& {\rm i} \int {\rm d}^4x {\rm e}^{{\rm i}q\cdot x} \langle 0 | T\left[J^{\alpha \beta}_7(x) \bar J^{\alpha^\prime \beta^\prime}_7(0)\right] | 0 \rangle \\ =& {\cal{G}}_{5/2}^{\alpha \beta,\alpha^\prime \beta^\prime} (\not q + M_{X_7})\; \Pi_7\left(q^2\right) \, , \end{aligned}

      (45)

      where {\cal{G}}_{3/2}^{\mu\nu} and {\cal{G}}_{5/2}^{\mu \nu,\,\rho \sigma} are coefficients of the spin-3/2 and spin-5/2 propagators, respectively.

      {\cal{G}}_{3/2}^{\mu\nu}(p) = g^{\mu\nu} - {1\over3} \gamma^\mu \gamma^\nu - {p^\mu\gamma^\nu - p^\nu\gamma^{\mu} \over 3m} - {2p^{\mu}p^\nu \over 3m^2} \, ,

      (46)

      \begin{aligned}[b] {\cal{G}}_{5/2}^{\mu \nu,\rho \sigma}(p) =& \frac{1}{2}(g^{\mu\rho}g^{\nu\sigma}+g^{\mu\sigma}g^{\nu\rho}) - \frac{1}{5}g^{\mu\nu}g^{\rho\sigma} \\ &- \frac{1}{10}(g^{\mu\rho}\gamma^\nu\gamma^\sigma + g^{\mu\sigma}\gamma^\nu\gamma^\rho + g^{\nu\rho}\gamma^\mu\gamma^\sigma + g^{\nu\sigma}\gamma^\mu\gamma^\rho) \end{aligned}

      \begin{aligned}[b] &+ \frac{1}{10m}\Bigl(g^{\mu\rho}(p^\nu\gamma^\sigma - p^\sigma\gamma^\nu) + g^{\mu\sigma}(p^\nu\gamma^\rho - p^\rho\gamma^\nu) \\ & + g^{\nu\rho}(p^\mu\gamma^\sigma - p^\sigma\gamma^\mu) + g^{\nu\sigma}(p^\mu\gamma^\rho - p^\rho\gamma^\mu)\Bigr) \\ &+ \frac{1}{5m^2}(g^{\mu\nu}p^\rho p^\sigma + g^{\rho\sigma}p^\mu p^\nu) \\ &- \frac{2}{5m^2}(g^{\mu\rho}p^\nu p^\sigma + g^{\mu\sigma}p^\nu p^\rho + g^{\nu\rho}p^\mu p^\sigma + g^{\nu\sigma}p^\mu p^\rho) \\ &+ \frac{1}{10m^2}\Bigl(\gamma^\mu p^\nu (\gamma^\rho p^\sigma + \gamma^\sigma p^\rho) + \gamma^\nu p^\mu (\gamma^\rho p^\sigma + \gamma^\sigma p^\rho)\Bigl) \\ &+ \frac{1}{5m^3}\Bigl(p^\rho p^\sigma (\gamma^\mu p^\nu + \gamma^\nu p^\mu ) - p^\mu p^\nu (\gamma^\rho p^\sigma + \gamma^\sigma p^\rho ) \Bigl) \\ &+ \frac{2}{5m^4}p^\mu p^\nu p^\rho p^\sigma \, . \end{aligned}

      (47)

      In the above expressions, we assume that the states X_{1\cdots7} have the same spin-parity quantum numbers as the currents J_{1\cdots7} so that we may use the "non- \gamma_5 coupling" in Eq. (42). Conversely, we must use the " \gamma_5 coupling,"

      \langle 0 | J_{1\cdots7} | X_{1\cdots7}^\prime \rangle = f_{X^\prime_{1\cdots7}} \gamma_5 u (p) \, ,

      (48)

      if the states X^\prime_{1\cdots7} have an opposite parity to the currents J_{1\cdots7} . We may alternatively use the partner currents \gamma_5 J_{1\cdots7} , which also have opposite parity.

      \langle 0 | \gamma_5 J_{1\cdots7} | X_{1\cdots7} \rangle = f_{X_{1\cdots7}} \gamma_5 u (p) \, .

      (49)

      From Eqs. (48) and (49), we can derive another "non- \gamma_5 coupling" between \gamma_5 J_{1\cdots7} and X^\prime_{1\cdots7} , expressed as

      \langle 0 | \gamma_5 J_{1\cdots7} | X_{1\cdots7}^\prime \rangle = f_{X^\prime_{1\cdots7}} u (p) \, .

      (50)

      We refer to Refs. [8992] for detailed discussions.

      The two-point correlation functions derived from Eqs. (48) and (49) are similar to Eqs. (43)–(45) but with (\not q + M_{X}) replaced by (- \not q + M_{X}) . Based on this feature, we can extract the parities of X_{1\cdots7} ; we use the terms proportional to \bf 1 to evaluate the masses of X_{1\cdots7} , which are then compared with the terms proportional to \not q to extract their parities.

      In QCD sum rule studies, we must calculate the two-point correlation function \Pi\left(q^2\right) at both the hadron and quark-gluon levels. At the hadron level, we use the dispersion relation to express this as

      \Pi(q^2)={\frac{1}{\pi}}\int^\infty_{s_<}\frac{{\rm{Im}} \Pi(s)}{s-q^2-{\rm i}\varepsilon}{\rm d}s \, ,

      (51)

      with s_< the physical threshold. We define the imaginary part of the correlation function as the spectral density \rho(s) , which can be evaluated at the hadron level by inserting the intermediate hadron states \sum_n|n\rangle\langle n| as follows:

      \begin{aligned}[b] \rho_{\rm{phen}}(s) \equiv& {\rm{Im}}\Pi(s)/\pi \\ =& \sum_n\delta(s-M^2_n)\langle 0|\eta|n\rangle\langle n|{\eta^\dagger}|0\rangle \\ =& f_X^2\delta(s-m_X^2)+ \rm{continuum}. \end{aligned}

      (52)

      In the last step, we adopt typical parametrization of one-pole dominance for the ground state X along with a continuum contribution.

      At the quark-gluon level, we calculate \Pi\left(q^2\right) using the method of operator product expansion (OPE) and extract its corresponding spectral density \rho_{\rm{OPE}}(s) . After performing the Borel transformation at both the hadron and quark-gluon levels, we approximate the continuum using the spectral density above a threshold value s_0 (quark-hadron duality) and arrive at the sum rule equation

      \Pi(s_0, M_{\rm B}^2) \equiv f^2_X {\rm e}^{-M_X^2/M_{\rm B}^2} = \int^{s_0}_{s_<} {\rm e}^{-s/M_{\rm B}^2}\rho_{\rm{OPE}}(s){\rm d}s \, .

      (53)

      This can be used to further calculate M_X and f_X through

      M^2_X(s_0, M_{\rm B}) = \frac{\displaystyle\int^{s_0}_{s_<} {\rm e}^{-s/M_{\rm B}^2}s\rho_{\rm{OPE}}(s){\rm d}s}{\displaystyle\int^{s_0}_{s_<} {\rm e}^{-s/M_{\rm B}^2}\rho_{\rm{OPE}}(s){\rm d}s} \, ,

      (54)

      f_X^2(s_0, M_{\rm B}) = {\rm e}^{(M_X^2(s_0, M_{\rm B}))/ M_{\rm B}^2} \int^{s_0}_{s_<} {\rm e}^{-s/M_{\rm B}^2}\rho_{\rm{OPE}}(s){\rm d}s \, .

      (55)

      In this study, we calculate OPEs at the leading order of \alpha_s and up to the D({\rm{imension}}) = 10 terms, including the perturbative term, charm quark mass, quark condensate \langle \bar q q \rangle ,gluon condensate \langle g_s^2 GG \rangle , quark-gluon mixed condensate \langle g_s \bar q \sigma G q \rangle , and their combinations \langle \bar q q \rangle^2 , \langle \bar q q \rangle\langle g_s \bar q \sigma G q \rangle , \langle \bar q q \rangle^3 , and \langle g_s \bar q \sigma G q \rangle^2 . We summarize the obtained spectral densities \rho_{1\cdots7}(s) in Appendix A, which are extracted from the currents J_{1\cdots7} , respectively.

      In these calculations, we ignore chirally suppressed terms with light quark masses and adoptthe factorization assumption of vacuum saturation for higher dimensional condensates, that is, \langle (\bar q q)^2 \rangle = \langle \bar q q \rangle^2 , \langle (\bar q q) (g_s \bar q \sigma G q) \rangle = \langle \bar q q \rangle\langle g_s \bar q \sigma G q \rangle , \langle (\bar q q)^3 \rangle = \langle \bar q q \rangle^3 , and \langle (g_s \bar q \sigma G q)^2 \rangle = \langle g_s \bar q \sigma G q \rangle^2 . We find that the D=3 quark condensate {\langle\bar qq\rangle} and the D=5 mixed condensate \langle g_s \bar q \sigma G q \rangle are both multiplied by the charm quark mass m_c and are thus important power corrections.

      In the following subsection, we use the spectral densities \rho_{1\cdots7}(s) to perform numerical analyses and calculate the masses and decay constants of X_{1\cdots7} . First, however, let us investigate the current J_1 as an example. This has the quantum number J^P = 1/2^- and couples to the \bar D \Sigma_c molecular state X_1 . Its spectral density \rho_1(s) is given in Eq. (A1). We find that the terms multiplied by m_c are almost positively proportional to the terms multiplied by \not q . Hence, the extracted parity of X_1 is found to be negative, which is the same as J_1 . In other words, J_1 mainly couples to a negative-parity state. Similarly, all the \bar D^{(*)} \Sigma_c^{(*)} molecular states defined in Eqs. (18)–(24) are found to have negative parity.

    • B.   Mass analyses

    • In this subsection, we use the spectral densities \rho_{1\cdots7}(s) extracted from the currents J_{1\cdots7} to perform numerical analyses and calculate the masses and decay constants of X_{1\cdots7} . As discussed in the previous subsection, we only use the terms proportional to m_c to achieve this.

      We use the current J_1 as an example, whose spectral density \rho_1(s) can be found in Eq. (A1), and apply the following QCD sum rule parameter values [93101]:

      \begin{aligned}[b] m_c=& 1.275 ^{+0.025}_{-0.035} \rm{ GeV} \, , \\ \langle \bar qq \rangle =& - (0.24 \pm 0.01)^3 \rm{ GeV}^3 \, , \\ \langle g_s^2GG\rangle =& (0.48 \pm 0.14) \rm{ GeV}^4\, , \\ \langle g_s \bar q \sigma G q \rangle =& M_0^2 \times \langle \bar qq \rangle\, , \\ M_0^2 =& (0.8 \pm 0.2) \rm{ GeV}^2 \, , \end{aligned}

      (56)

      where the running mass in the \overline{MS} scheme is used for the charm quark.

      There are two free parameters in Eqs. (54) and (55), the Borel mass M_{\rm B} and threshold value s_0 . We use two criteria to constrain the Borel mass M_{\rm B} for a fixed s_0 . The first criterion is to ensure the convergence of the OPE series. This is achieved by requiring the D=10 terms ( m_c \langle \bar q q \rangle^3 and \langle g_s \bar q \sigma G q \rangle^2 ) to be less than 10% so that the lower limit of M_{\rm B} can be determined.

      \rm{Convergence} \equiv \left|\frac{ \Pi^{D=10}(\infty, M_{\rm B}) }{ \Pi(\infty, M_{\rm B}) }\right| \leq 10\% \, .

      (57)

      We show this function in Fig. 2 using the solid curve and find that OPE convergence improves with increasing M_{\rm B} . This criterion leads to \left(M_{\rm B}^{\rm min}\right)^2 = 3.27 GeV2 when setting s_0 = 24 GeV ^2 .

      Figure 2.  Convergence (solid curve, defined in Eq. (57)) and pole-contribution (dashed curve, defined in Eq. (58)) as functions of the Borel mass M_{\rm B} . These curves are obtained using the current J_1 when setting s_0 = 24 GeV ^2 .

      The second criterion is to ensure the validity of one-pole parametrization. This is achieved by requiring the pole contribution to be larger than 40% so that the upper limit of M_{\rm B} can be determined.

      \rm{Pole-Contribution} \equiv \frac{ \Pi(s_0, M_{\rm B}) }{ \Pi(\infty, M_{\rm B}) } \geq 40\% \, .

      (58)

      We show this function in Fig. 2 using the dashed curve and find that it decreases with increasing M_{\rm B} . This criterion leads to \left(M_{\rm B}^{\rm max}\right)^2 = 3.52 GeV ^2 when setting s_0 = 24 GeV ^2 .

      Altogether, we extract the working region of the Borel mass to be 3.27 < M_{\rm B}^2 < 3.52 GeV ^2 for the current J_1 with the threshold value s_0 = 24 GeV ^2 . We show variations in M_{X_1} and f_{X_1} with respect to the Borel mass M_{\rm B} in Fig. 3. They are shown in a broader region, 3.0 \leq M_{\rm B}^2 \leq 4.0 GeV ^2 , and are more stable inside the above Borel window.

      Figure 3.  Variations in the mass M_{X} (left) and decay constant f_{X} (right) with respect to the Borel mass M_{\rm B}, calculated using the current J_1. In both panels, the short-dashed, solid, and long-dashed curves are obtained by setting s_0 = 23, 24, and 25 GeV^2, respectively.

      Redoing the same procedures by changing s_0 , we find that there are non-vanishing Borel windows as long as s_0 \geq s_0^{\rm min} = 22.4 GeV ^2 . Accordingly, we choose s_0 to be slightly larger with an uncertainty of \pm1.0 GeV, that is, s_0 = 24.0 \pm 1.0 GeV ^2 . Overall, our working regions for the current J_1 are determined to be 23.0 \leq s_0\leq 25.0 GeV ^2 and 3.27 \leq M_{\rm B}^2 \leq 3.52 GeV ^2 , for which we calculate the mass and decay constant of X_1 to be

      \begin{aligned}[b] M_{X_1} =& 4.30^{+0.10}_{-0.10} \rm{ GeV} \, , \\ f_{X_1} =& \left(1.19^{+0.19}_{-0.18}\right) \times 10^{-3} \rm{ GeV}^6 \, . \end{aligned}

      (59)

      Here, the central values correspond to M_{\rm B}^2=3.40 GeV ^2 and s_0 = 24.0 GeV ^2 . Their uncertainties originate from the threshold value s_0 , Borel mass M_{\rm B} , charm quark mass m_c , and various QCD sum rule parameters listed in Eq. (56). This mass value is consistent with the experimental mass of P_c(4312)^+ [5], revealing it to be the I = 1/2 \bar D \Sigma_c molecular state of J^P=1/2^- .

      Similarly, we use the spectral densities \rho_{2\cdots7}(s) extracted from the currents J_{2\cdots7} to perform numerical analyses and calculate the masses and decay constants of X_{2\cdots7} . In particular, the sum rule results extracted from the currents J_6^\alpha and J_7^{\alpha\beta} are

      \begin{aligned}[b] M_{X_6} =& 4.64^{+0.10}_{-0.10} \rm{ GeV} \, , \quad f_{X_6} = \left(1.01^{+0.15}_{-0.14}\right) \times 10^{-3} \rm{ GeV}^6 \, , \\ M_{X_7} =& 4.64^{+0.14}_{-0.12} \rm{ GeV} \, , \quad f_{X_7} = \left(0.77^{+0.12}_{-0.11}\right) \times 10^{-3} \rm{ GeV}^6 \, . \end{aligned}

      (60)

      These two mass values are both close to, but slightly larger than, the \bar D^* \Sigma_c^* threshold at M_{D^*} + M_{\Sigma_c^*} = 4527 MeV. To obtain a better description of the \bar D^* \Sigma_c^* molecular states that may lie just below the \bar D^* \Sigma_c^* threshold, we loosen the criterion given in Eq. (57) to

      \rm{Convergence} \equiv \left|\frac{ \Pi^{D=10}(\infty, M_{\rm B}) }{ \Pi(\infty, M_{\rm B}) }\right| \leq 15\% \, .

      (61)

      Now, the masses and decay constants extracted from the currents J_6^\alpha and J_7^{\alpha\beta} are modified to be

      \begin{aligned}[]b M^\prime_{X_6} =& 4.52^{+0.11}_{-0.11} \rm{ GeV} \, , \quad f^\prime_{X_6} = \left(0.85^{+0.14}_{-0.13}\right) \times 10^{-3} \rm{ GeV}^6 \, , \\ M^\prime_{X_7} =& 4.55^{+0.15}_{-0.13} \rm{ GeV} \, , \quad f^\prime_{X_7} = \left(0.65^{+0.11}_{-0.10}\right) \times 10^{-3} \rm{ GeV}^6 \, . \end{aligned}

      (62)

      Moreover, the mass of |\bar D \Sigma_c^*; 3/2^- \rangle is calculated to be 4.43^{+0.10}_{-0.10} GeV, which is consistent with, but also slightly larger than, the \bar D \Sigma_c^* threshold at M_{D} + M_{\Sigma_c^*} = 4385 MeV. All these divergences indicate that the accuracy of our QCD sum rule results is moderate but not good enough to extract the binding energies of the \bar D^{(*)} \Sigma_c^{(*)} molecular states. Therefore, our results can suggest but not determine a) whether these \bar D^{(*)} \Sigma_c^{(*)} molecular states exist, and b) whether they are bound or resonance states. However, in this study, we are more concerned with the ratios, that is, the relative production rates and relative branching ratios, whose uncertainties can be significantly reduced. Accordingly, the decay constants f_X calculated in this section are input parameters that are more important than the masses M_X . Note that the decay constants f_X can also be used within the QCD sum rule method to directly calculate the partial decay widths through the three-point correlation functions; however, we do not perform this in the present study.

      We summarize all the above sum rule results in Table 1. Our results are consistent with those of Ref. [102], where the authors applied the same QCD sum rule method to study both the I=1/2 \bar D^{(*)} \Sigma_c^{(*)} and I=3/2 molecular states. Our results support the interpretations of P_c(4440)^+ and P_c(4457)^+ [5] as the I = 1/2 \bar D^* \Sigma_c molecular states of J^P=1/2^- and 3/2^- . Again, the accuracy of our sum rule results is not good enough to distinguish or identify them. To better understand them, we study their production and decay properties in the following sections, where we find that P_c(4440)^+ and P_c(4457)^+ can be better interpreted in our framework as |\bar D^{*} \Sigma_c; 3/2^- \rangle and |\bar D^{*} \Sigma_c; 1/2^- \rangle , respectively.

      CurrentsConfigurations_0^{\rm min}/{\rm{GeV}}^2Working regionsPole (%)Mass/GeVf_X/GeV^6Candidate
      s_0/{\rm{GeV} }^2M_{\rm B}^2/{\rm{GeV} }^2
      J_1|\bar D \Sigma_c; 1/2^- \rangle22.424.0\pm1.03.273.5240484.30^{+0.10}_{-0.10}\left(1.19^{+0.19}_{-0.18}\right) \times 10^{-3}P_c(4312)^+
      J_2|\bar D^* \Sigma_c; 1/2^- \rangle25.527.0\pm1.03.783.9940464.48^{+0.10}_{-0.10}\left(2.24^{+0.34}_{-0.30}\right) \times 10^{-3}P_c(4457)^+
      J_3|\bar D^* \Sigma_c; 3/2^- \rangle24.626.0\pm1.03.513.7240464.46^{+0.11}_{-0.10}\left(1.15^{+0.18}_{-0.16}\right) \times 10^{-3}P_c(4440)^+
      J_4|\bar D \Sigma_c^*; 3/2^- \rangle24.225.0\pm1.03.333.4540444.43^{+0.10}_{-0.10}\left(0.65^{+0.11}_{-0.10}\right) \times 10^{-3}
      J_5|\bar D^* \Sigma_c^*; 1/2^- \rangle26.027.0\pm1.03.433.5640444.51^{+0.10}_{-0.11}\left(1.12^{+0.19}_{-0.17}\right) \times 10^{-3}
      J_6|\bar D^* \Sigma_c^*; 3/2^- \rangle25.327.0\pm1.03.693.9840484.52^{+0.11}_{-0.11}\left(0.85^{+0.14}_{-0.13}\right) \times 10^{-3}
      J_7|\bar D^* \Sigma_c^*; 5/2^- \rangle24.726.0\pm1.03.223.4240464.55^{+0.15}_{-0.13}\left(0.65^{+0.11}_{-0.10}\right) \times 10^{-3}

      Table 1.  Masses and decay constants of X_{1\cdots7} extracted from the currents J_{1\cdots7} .

    IV.   PRODUCTION THROUGH CURRENT ALGEBRA
    • In this section, we study the production of the \bar D^{(*)} \Sigma_c^{(*)} molecular states in \Lambda_b^0 decays using current algebra. We calculate their relative production rates, that is, {\cal{B}}(\Lambda_b^0 \to P_c K^-):{\cal{B}}(\Lambda_b^0 \to P_c^\prime K^-) , with P_c and P_c^\prime as two different states. We refer to Refs. [103, 104] for additional relevant studies.

      P_c(4312)^+ , P_c(4440)^+ , and P_c(4457)^+ were observed by the LHCb in the J/\psi p invariant mass spectrum of \Lambda_b^0 \to J/\psi p K^- decays. The quark content of the initial state \Lambda_b^0 is udb . In this three-body decay process, the b quark first decays into a c quark by emitting a W^- boson, and the W^- boson translates into a pair of \bar c and s quarks, both of which are Cabibbo-favored. Then, they obtain a pair of \bar u and u quarks from the vacuum. Finally, they hadronize into the three final states J/\psi p K^- .

      \Lambda_b^0 = udb \to ud c\; \bar c s \to udc\; \bar c s\; \bar u u \to J/\psi p K^- \, .

      (63)

      Hence, the total quark content of the final states is udc \bar c s \bar u u , where the intermediate states D^{(*)-} \Sigma_c^{(*)++} K^- and \bar D^{(*)0} \Sigma_c^{(*)+} K^- can also be produced.

      We study the production of the \bar D^{(*)} \Sigma_c^{(*)} molecular states by investigating the mechanisms depicted in Fig. 4. Note that the u quark from the vacuum must exchange with either the u or d quark of \Lambda_b^0 because the ud pair of \Lambda_b^0 is in a state of I=0 , whereas \Sigma_c and \Sigma_c^{*} both have I=1 .

      Figure 4.  Production mechanisms of the \bar D^{(*)} \Sigma_c^{(*)} molecular states in \Lambda_b^0 decays.

      As depicted in Fig. 4, the weak interaction only involves the initial b quark and the final c \bar c s quarks. Hence, by considering the quark pair produced from the vacuum to be \bar u u + \bar d d of I=0 , the isospin of the entire process is also conserved at I=0 .

      \begin{aligned}[b] \Lambda_b^0 \to& ud c\; \bar c s\; (\bar u u + \bar d d) \\ \to& \sqrt{1\over3} D^{(*)-} \Sigma_c^{(*)++} K^- + \sqrt{1\over3} \bar D^{(*)0} \Sigma_c^{(*)0} \bar K^0 \\ & - \sqrt{1\over6} D^{(*)-} \Sigma_c^{(*)+} \bar K^0 - \sqrt{1\over6} \bar D^{(*)0} \Sigma_c^{(*)+} K^-\, . \end{aligned}

      (64)

      The four fixed isospin factors allow us to consider only the D^{(*)-} \Sigma_c^{(*)++} K^- final state because the results derived from the \bar D^{(*)0} \Sigma_c^{(*)+} K^- final state are the same. Accordingly, we only need to consider the exchange of the u quark from the vacuum and the d quark from \Lambda_b^0 , which are depicted in Fig. 4(a).

      Summarizing the above discussions, in this section, we calculate the relative production rates of the \bar D^{(*)} \Sigma_c^{(*)} molecular states in \Lambda_b^0 decays by investigating three-body \Lambda_b^0 \to D^{(*)-} \Sigma_c^{(*)++} K^- decays, whose mechanism is depicted in Fig. 4(a). We develop a Fierz rearrangement to describe this process in Sec. IV.A and use it to perform numerical analyses in Sec. IV.B.

    • A.   Fierz rearrangement

    • To describe the production mechanism depicted in Fig. 4(a), we use the color rearrangement given in Eq. (12) twice to obtain

      \begin{aligned}[b]\\ \epsilon^{abc} \delta^{de} \delta^{fg} =& \left( \epsilon^{ebc} \delta^{da} + \epsilon^{aec} \delta^{db} + \epsilon^{abe} \delta^{dc} \right) \times \delta^{fg} = \epsilon^{gbc} \delta^{da} \delta^{fe} + \epsilon^{egc} \delta^{da} \delta^{fb} + \epsilon^{ebg} \delta^{da} \delta^{fc} \\ &+ \epsilon^{gec} \delta^{db} \delta^{fa} + \epsilon^{agc} \delta^{db} \delta^{fe} + \epsilon^{aeg} \delta^{db} \delta^{fc} + \epsilon^{gbe} \delta^{dc} \delta^{fa} + \epsilon^{age} \delta^{dc} \delta^{fb} + \epsilon^{abg} \delta^{dc} \delta^{fe} \, . \end{aligned}

      (65)

      Given the initial color structure

      [\epsilon^{abc} u_a d_b c_c][\delta^{de}\bar c_d s_e][\delta^{fg}\bar u_f u_g]

      we require the fifth to be

      [\epsilon^{agc}u_a u_g c_c] [\delta^{db} \bar c_d d_b] [\delta^{fe}\bar u_f s_e]

      which corresponds to the D^{(*)-} \Sigma_c^{(*)++} K^- final state.

      Furthermore, we must apply Fierz transformation twice to (a) interchange the d_b and u_g quarks and (b) interchange the d_b and s_e quarks. Note that Fierz rearrangement in Lorentz space is a matrix identity. It is valid if each quark field in the initial and final currents is at the same location.

      The key formula is as follows:

      \begin{array}{*{20}{l}} \Lambda_b^0 &\xrightarrow{\; \; \; \; \; \; \; \; \; \; \; \; \; }& J_{\Lambda_b^0} = [\epsilon^{abc}u_a^T \mathbb{C} \gamma_5 d_b b_c], \end{array}

      (66)

      \begin{array}{*{20}{l}}\quad\quad \xrightarrow{\; \; \; \; \rm weak\; \; \; \; } [\epsilon^{abc}u_a^T \mathbb{C} \gamma_5 d_b \gamma_\rho(1 - \gamma_5) c_c] \; \times\; [\delta^{de}\bar c_d \gamma^\rho(1 - \gamma_5) s_e], \end{array}

      (67)

      \begin{array}{*{20}{l}} \quad\quad\xrightarrow{\; \; \; \; \rm QPC\; \; \; \; } [\epsilon^{abc}u_a^T \mathbb{C} \gamma_5 d_b \gamma_\rho(1 - \gamma_5) c_c] \; \times\; [\delta^{de}\bar c_d \gamma^\rho(1 - \gamma_5) s_e] \; \times\; [\delta^{fg}\bar u_f u_g], \end{array}

      (68)

      \begin{array}{*{20}{l}} \quad\quad\underline{\underline {{\rm{\;\;color\;\;}}}} \epsilon^{agc}\delta^{db}\delta^{fe} \times u_a^T \mathbb{C} \gamma_5 d_b \gamma_\rho(1 - \gamma_5) c_c \times \bar c_d \gamma^\rho(1 - \gamma_5) s_e \times \bar u_f u_g + \cdots , \end{array}

      (69)

      \begin{array}{*{20}{l}} \quad\quad\underline{\underline {{\rm{Fierz:}}d_b \leftrightarrow u_g}} -{\delta^{db}\delta^{fe}\over4} \times [\epsilon^{agc}u_a^T \mathbb{C} \gamma_\mu u_g \gamma_\rho(1 - \gamma_5) c_c] \times \bar c_d \gamma^\rho(1 - \gamma_5) s_e \times \bar u_f \gamma^\mu \gamma_5 d_b + \cdots, \end{array}

      (70)

      \begin{aligned}[b]\quad\quad \underline{\underline {{\rm{Fierz:}}d_b \leftrightarrow s_e}} +& {1 + \gamma_5 \over16} \times [\epsilon^{agc}u_a^T \mathbb{C} \gamma_\mu u_g \gamma^\mu \gamma_5 c_c] \times [\delta^{db} \bar c_d \gamma_5 d_b] \times [\delta^{fe}\bar u_f \gamma_5 s_e] \\& + {(1 + \gamma_5) (g^{\nu\rho} - {\rm i} \sigma^{\nu\rho}) \over 32} \times [\epsilon^{agc}u_a^T \mathbb{C} \gamma_\mu u_g \gamma^\mu \gamma_5 c_c] \times [\delta^{db} \bar c_d \gamma_\nu d_b] \times [\delta^{fe}\bar u_f \gamma_\rho \gamma_5 s_e] \\ & + {(1 + \gamma_5) (g^{\alpha\nu} \gamma^\rho + g^{\alpha\rho} \gamma^\nu) \over 16} \times [P_{\alpha \mu}^{3/2}\epsilon^{agc}u_a^T \mathbb{C} \gamma^\mu u_g c_c] \times [\delta^{db} \bar c_d \gamma_\nu d_b] \times [\delta^{fe}\bar u_f \gamma_\rho \gamma_5 s_e] + \cdots, \end{aligned}

      (71)

      \begin{aligned}[b]\quad\quad \underline{\underline { \; \; \; \; \; \; \; \; \; \; \; \; \; \;}} & + {1 + \gamma_5 \over8\sqrt2} \times \xi_1 \times [\bar u_a \gamma_5 s_a] + {(1 + \gamma_5) (g_{\nu\rho} - {\rm i} \sigma_{\nu\rho}) \over 16\sqrt2} \left(\xi_3^\nu - {1\over4}\gamma^\nu\gamma_5\xi_2\right) [\bar u_a \gamma^\rho \gamma_5 s_a] \\ & + {(1 + \gamma_5) (g_{\alpha\nu} \gamma_\rho + g_{\alpha\rho} \gamma_\nu) \over 8\sqrt2} \left(\xi_7^{\alpha\nu} - {1\over9}\gamma^\alpha\gamma_5\xi_6^\nu - {1\over9}\gamma^\nu\gamma_5\xi_6^\alpha + {2\over9} g^{\alpha\nu}\xi_5 \right) [\bar u_a \gamma^\rho \gamma_5 s_a] + \cdots \, . \end{aligned}

      (72)

      A brief explanation is given as follows:

      ● Eq. (67) describes the Cabibbo-favored weak decay of b\to c + \bar{c}s via the V-A current.

      ● Eq. (68) describes the production of the \bar u and u quark pair from the vacuum via the ^3P_0 quark pair creation mechanism.

      ● In Eq. (69), we apply the double-color rearrangement given in Eq. (65).

      ● In Eq. (70), we apply Fierz transformation to interchange the d_b and u_g quarks.

      ● In Eq. (71), we apply Fierz transformation to interchange the d_b and s_e quarks.

      ● In Eq. (72), we combine the five u_a u_g c_c \bar c_d d_b quarks so that the D^{(*)-} \Sigma_c^{(*)++} molecular states can be produced.

      In the above expression, we only consider \xi_{1\cdots7} defined in Eqs. (34)–(40), which couple to the D^{(*)-} \Sigma_c^{(*)++} molecular states through an S-wave. In reality, there may be other currents coupling to these states through a P-wave, which are not included in the present study, such as

      \begin{aligned}[b] \xi_6^{\prime \alpha\beta} =& {1\over\sqrt2}\; P^{\alpha\beta,\nu\rho}_{3/2}\; [\delta^{ab} \bar c_a \gamma_\nu d_b] \; P^{3/2}_{\rho\mu} [\epsilon^{cde} u_c^T \mathbb{C} \gamma^\mu u_d c_e] \\ =& P^{\alpha\beta,\nu\rho}_{3/2}\; D^{*-}_\nu \; \; \Sigma_{c;\rho}^{*++} \, , \end{aligned}

      (73)

      where P_{3/2}^{\mu\nu,\rho\sigma} is the spin-3/2 projection operator with two antisymmetric Lorentz indices,

      \begin{aligned}[b] P_{3/2}^{\mu\nu,\,\rho\sigma} =& {1\over2} g^{\mu\rho}g^{\nu\sigma} - {1\over2} g^{\mu\sigma}g^{\nu\rho} + {1\over6} \sigma^{\mu\nu}\sigma^{\rho\sigma} \\ & - {1\over4}g^{\mu\rho}\gamma^\nu\gamma^\sigma + {1\over4}g^{\mu\sigma}\gamma^\nu\gamma^\rho \\ & - {1\over4}g^{\nu\sigma}\gamma^\mu\gamma^\rho + {1\over4}g^{\nu\rho}\gamma^\mu\gamma^\sigma \, . \end{aligned}

      (74)

      The current \eta_6^{\prime \alpha\beta} couples to | D^{*-} \Sigma_c^{*++}; 3/2^- \rangle through

      \langle 0| \eta_6^{\prime \alpha\beta} | D^{*-} \Sigma_c^{*++}; 3/2^- \rangle = i f^T_{6^\prime} (p^\alpha u^\beta - p^\beta u^\alpha) \, ,

      (75)

      where u_\alpha is the spinor of | D^{*-} \Sigma_c^{*++}; 3/2^- \rangle . It can also couple to another state of J^P = 3/2^+ .

      Consequently, |\bar D \Sigma_c^*; 3/2^- \rangle may still be produced in \Lambda_b^0 decays, although its directly corresponding current \xi_4^\alpha (and hence J_4^\alpha ) does not appear in Eq. (72). Additionally, omission of the "other possible currents" produces theoretical uncertainties.

    • B.   Production analyses

    • In this subsection, we use the Fierz rearrangement given in Eq. (72) to perform numerical analyses. We consider the isospin factors of Eqs. (25) and (64) and directly calculate the relative production rates of the I=1/2 \bar D^{(*)} \Sigma_c^{(*)} molecular states in \Lambda_b^0 decays. To achieve this, we require the following couplings to K^- :

      \begin{aligned}[b] \langle 0 | \bar u_a \gamma_5 s_a | K^-(q) \rangle =& \lambda_{K} \, , \\ \langle 0 | \bar u_a \gamma_\mu \gamma_5 s_a | K^-(q) \rangle =& {\rm i} q_\mu f_{K} \, , \end{aligned}

      (76)

      where f_{K}= 155.6 MeV [2], and \lambda_{K} = \dfrac{f_{K}^2 m_K}{ m_u + m_s} .

      We extract from Eq. (72) the following decay channels:

      1. The decay of \Lambda_b^0 into |\bar D \Sigma_c; 1/2^- \rangle K^- is contributed by \xi_1 \times [\bar u_a \gamma_5 s_a] .

      \begin{aligned}[b] & \langle \Lambda_b^0(q) \; |\; \bar D \Sigma_c; 1/2^-(q_1)\; K^-(q_2) \rangle \\ \approx& -c\; {\rm i} \lambda_K f_{|\bar D \Sigma_c; 1/2^- \rangle} \; \bar u_{\Lambda_b^0} \left( {1 + \gamma_5 \over16} \right) u \, , \end{aligned}

      (77)

      where u_{\Lambda_b^0} and u are spinors of \Lambda_b^0 and |\bar D \Sigma_c; 1/2^- \rangle , respectively. The decay constant f_{|\bar D \Sigma_c; 1/2^- \rangle} has been calculated in the previous section and given in Table 1. The overall factor c is related to a) the coupling of J_{\Lambda_b^0} to \Lambda_b^0 , b) the weak and ^3P_0 decay processes described by Eqs. (67) and (68), and c) the isospin factors of Eqs. (25) and (64). We use the same factor c for all seven \bar D^{(*)} \Sigma_c^{(*)} molecular states. This can cause a significant theoretical uncertainty, which is not taken into account in this study.

      2. The decay of \Lambda_b^0 into |\bar D^* \Sigma_c; 1/2^- \rangle K^- is contributed by \xi_2 \times [\bar u_a \gamma^\rho \gamma_5 s_a] .

      \begin{aligned}[b] & \langle \Lambda_b^0(q) \; |\; \bar D^* \Sigma_c; 1/2^-(q_1)\; K^-(q_2) \rangle \\ \approx& c\; {\rm i} f_K f_{|\bar D^* \Sigma_c; 1/2^- \rangle} q_2^\rho \\ &\times \bar u_{\Lambda_b^0} \left( {(1 + \gamma_5) (g_{\nu\rho} - {\rm i} \sigma_{\nu\rho}) \over 32} \cdot \left(- {1\over4}\gamma^\nu\gamma_5\right) \right) u \, , \end{aligned}

      (78)

      where u and f_{|\bar D^* \Sigma_c; 1/2^- \rangle} are the spinor and decay constant of |\bar D^* \Sigma_c; 1/2^- \rangle , respectively.

      3. The decay of \Lambda_b^0 into |\bar D^* \Sigma_c; 3/2^- \rangle K^- is contributed by \xi_3^\nu \times [\bar u_a \gamma^\rho \gamma_5 s_a] .

      \begin{aligned}[b] & \langle \Lambda_b^0(q) \; |\; \bar D^* \Sigma_c; 3/2^-(q_1)\; K^-(q_2) \rangle \\ \approx& c\; {\rm i} f_K f_{|\bar D^* \Sigma_c; 3/2^- \rangle} q_2^\rho \\ &\times \bar u_{\Lambda_b^0} \left( {(1 + \gamma_5) (g_{\nu\rho} - {\rm i} \sigma_{\nu\rho}) \over 32} \right) u^\nu \, , \end{aligned}

      (79)

      where u^\nu and f_{|\bar D^* \Sigma_c; 3/2^- \rangle} are the spinor and decay constant of |\bar D^* \Sigma_c; 3/2^- \rangle , respectively.

      4. The decay of \Lambda_b^0 into |\bar D^* \Sigma_c^*; 1/2^- \rangle K^- is contributed by \xi_5 \times [\bar u_a \gamma^\rho \gamma_5 s_a] :

      \begin{aligned}[b] & \langle \Lambda_b^0(q) \; |\; \bar D^* \Sigma_c^*; 1/2^-(q_1)\; K^-(q_2) \rangle \\ \approx& c\; {\rm i} f_K f_{|\bar D^* \Sigma_c^*; 1/2^- \rangle} q_2^\rho \\ &\times \bar u_{\Lambda_b^0} \left( {(1 + \gamma_5) (g_{\alpha\nu} \gamma_\rho + g_{\alpha\rho} \gamma_\nu) \over 16} \cdot {2\over9} g^{\alpha\nu} \right) u \, , \end{aligned}

      (80)

      where u and f_{|\bar D^* \Sigma_c^*; 1/2^- \rangle} are the spinor and decay constant of |\bar D^* \Sigma_c^*; 1/2^- \rangle , respectively.

      5. The decay of \Lambda_b^0 into |\bar D^* \Sigma_c^*; 3/2^- \rangle K^- is contributed by \xi_6^\beta \times [\bar u_a \gamma^\rho \gamma_5 s_a] .

      \begin{aligned}[b]& \langle \Lambda_b^0(q) \; |\; \bar D^* \Sigma_c^*; 3/2^-(q_1)\; K^-(q_2) \rangle \\ \approx& c\; {\rm i} f_K f_{|\bar D^* \Sigma_c^*; 3/2^- \rangle} q_2^\rho \\ & \times \bar u_{\Lambda_b^0} \Bigg( {(1 + \gamma_5) (g_{\alpha\nu} \gamma_\rho + g_{\alpha\rho} \gamma_\nu) \over 16} \\ & \times \left( - {1\over9}\gamma^\alpha\gamma_5 g^{\nu\beta} - {1\over9}\gamma^\nu\gamma_5 g^{\alpha\beta} \right) \Bigg) u_\beta \, , \end{aligned}

      (81)

      where u_\beta and f_{|\bar D^* \Sigma_c^*; 3/2^- \rangle} are the spinor and decay constant of |\bar D^* \Sigma_c^*; 3/2^- \rangle , respectively.

      6. The decay of \Lambda_b^0 into |\bar D^* \Sigma_c^*; 5/2^- \rangle K^- is contributed by \xi_7^{\alpha\nu} \times [\bar u_a \gamma^\rho \gamma_5 s_a] .

      \begin{aligned}[b] & \langle \Lambda_b^0(q) \; |\; \bar D^* \Sigma_c^*; 5/2^-(q_1)\; K^-(q_2) \rangle \\ \approx& c\; {\rm i} f_K f_{|\bar D^* \Sigma_c^*; 5/2^- \rangle} q_2^\rho \\ &\times \bar u_{\Lambda_b^0} \left( {(1 + \gamma_5) (g_{\alpha\nu} \gamma_\rho + g_{\alpha\rho} \gamma_\nu) \over 16} \right) u^{\alpha\nu} \, , \end{aligned}

      (82)

      where u^{\alpha\nu} and f_{|\bar D^* \Sigma_c^*; 5/2^- \rangle} are the spinor and decay constant of |\bar D^* \Sigma_c^*; 5/2^- \rangle , respectively.

      We find that P_c(4312)^+ , P_c(4440)^+ , and P_c(4457)^+ can be well interpreted in our framework as |\bar D \Sigma_c; 1/2^- \rangle , |\bar D^{*} \Sigma_c; 3/2^- \rangle , and |\bar D^{*} \Sigma_c; 1/2^- \rangle , respectively. Accordingly, we assume the masses of the \bar D^{(*)} \Sigma_c^{(*)} molecular states to be

      \begin{aligned}[b] M_{|\bar D \Sigma_c; 1/2^- \rangle} =& M_{P_c(4312)^+} = 4311.9\; {\rm{MeV}} \, , \\ M_{|\bar D^{*} \Sigma_c; 1/2^- \rangle} =& M_{P_c(4457)^+} = 4457.3\; {\rm{MeV}} \, , \\ M_{|\bar D^{*} \Sigma_c; 3/2^- \rangle} =& M_{P_c(4440)^+} = 4440.3\; {\rm{MeV}} \, , \\ M_{|\bar D \Sigma_c^{*}; 3/2^- \rangle} \approx& M_{D} + M_{\Sigma_c^*} = 4385\; {\rm{MeV}} \, , \\ M_{|\bar D^{*} \Sigma_c^*; 1/2^- \rangle} \approx& M_{D^*} + M_{\Sigma_c^*} = 4527\; {\rm{MeV}} \, , \\ M_{|\bar D^{*} \Sigma_c^*; 3/2^- \rangle} \approx& M_{D^*} + M_{\Sigma_c^*} = 4527\; {\rm{MeV}} \, , \\ M_{|\bar D^{*} \Sigma_c^*; 5/2^- \rangle} \approx& M_{D^*} + M_{\Sigma_c^*} = 4527\; {\rm{MeV}} \, . \end{aligned}

      (83)

      Now, we can summarize the above production amplitudes to obtain the following partial decay widths:

      \begin{aligned}[b] \Gamma(\Lambda_b^0 \to |\bar D \Sigma_c \rangle_{1/2^-} K^-) =& c^2\; 6.15 \times 10^{-11}\; {\rm{GeV}}^{17} \, , \\ \Gamma(\Lambda_b^0 \to |\bar D^* \Sigma_c \rangle_{1/2^-} K^-) =& c^2\; 8.76 \times 10^{-12}\; {\rm{GeV}}^{17} \, , \\ \Gamma(\Lambda_b^0 \to |\bar D^* \Sigma_c \rangle_{3/2^-} K^-) =& c^2\; 7.52 \times 10^{-12}\; {\rm{GeV}}^{17} \, , \\ \Gamma(\Lambda_b^0 \to |\bar D \Sigma_c^* \rangle_{3/2^-} K^-) =& 0 \\ \Gamma(\Lambda_b^0 \to |\bar D^* \Sigma_c^* \rangle_{1/2^-} K^-) =& c^2\; 3.57 \times 10^{-11}\; {\rm{GeV}}^{17} \, , \\ \Gamma(\Lambda_b^0 \to |\bar D^* \Sigma_c^* \rangle_{3/2^-} K^-) =& c^2\; 1.38 \times 10^{-12}\; {\rm{GeV}}^{17} \, , \\ \Gamma(\Lambda_b^0 \to |\bar D^* \Sigma_c^* \rangle_{5/2^-} K^-) =& 0 \, . \end{aligned}

      (84)

      From these values, we derive the following relativeproduction rates, {\cal{R}}_1\,(P_c) \;\equiv\; {{\cal{B}}\,\left(\Lambda_b^0 \rightarrow P_c K^- \right) \,/ \, {\cal{B}}\,\left(\Lambda_b^0 \;\rightarrow |\bar D^* \Sigma_c \rangle_{3/2^-} K^- \right)}:

      \begin{aligned}[b]\\[-5pt] & {{\cal{B}}\Bigg(\Lambda_b^0 \rightarrow K^-\Big( |\bar D \Sigma_c \rangle_{1/2^-} :|\bar D^* \Sigma_c \rangle_{1/2^-} :|\bar D^* \Sigma_c \rangle_{3/2^-} :|\bar D \Sigma_c^* \rangle_{3/2^-} :|\bar D^* \Sigma_c^* \rangle_{1/2^-} :|\bar D^* \Sigma_c^* \rangle_{3/2^-} :|\bar D^* \Sigma_c^* \rangle_{5/2^-} \Big)\Bigg) \over {\cal{B}}\left(\Lambda_b^0 \rightarrow |\bar D^* \Sigma_c \rangle_{3/2^-} K^- \right)} \\ \approx & \; \; \; \; \; \; \; \; \; \; \; \; \; \; \; \; \; \; \; \; \; \; \; \; \;\quad\quad 8.2 \; \; \; \; : \; \; \; \; \; \,1.2\,\; \; \; \; \; : \; \; \; \; \; \; \; {\bf1}\;\;\; \; \; \; \; \; \, : \; \; \; \; \; \; 0\; \;\;\;\; \; \; \; \; : \; \; \; \; \; \,4.8\,\; \; \; \; \;\; : \; \; \; \; \; 0.18\; \; \; \; \; : \; \; \; \; \; 0\; \, . \end{aligned}

      (85)
    V.   DECAY PROPERTIES THROUGH THE FIERZ REARRANGEMENT
    • We have applied the Fierz rearrangement [105] of the Dirac and color indices to study the decay properties of P_c(4312)^+ , P_c(4440)^+ , and P_c(4457)^+ as \bar D^{(*)} \Sigma_c molecular states based on the currents J_{1\cdots3} [76]. In this section, we follow the same procedures to study the decay properties of the \bar D^{(*)} \Sigma_c^* molecular states using the currents J_{4\cdots7} . We study their decays into charmonium mesons and spin-1/2 light baryons as well as charmed mesons and spin-1/2 charmed baryons, such as J/\psi p and \bar D \Lambda_c .

      We refer to Ref. [76] for detailed discussions. This method has been applied to study the strong decay properties of Z_c(3900) , X(3872) , and X(6900) in Refs. [106108], and a similar arrangement of spin and color indices in the nonrelativistic case has been applied to study the decay properties of the XYZ and P_c states in Refs. [67, 69, 109113].

    • A.   Input parameters

    • To study the decays of the \bar D^{(*)} \Sigma_c^{*} molecular states into charmonium mesons and light baryons, we must use the \theta(x) currents. We can construct them by combining charmonium operators and light baryon fields, as done in Ref. [76]. In the present study, we require couplings of charmonium operators to charmonium states, which are listed in Table 2. We also require Ioffe's light baryon field [7274, 114118]

      Operators I^GJ^{PC} Mesons I^GJ^{PC} Couplings Decay constants
      I^{S} = \bar c c 0^+0^{++} \chi_{c0}(1P) 0^+0^{++} \langle 0 | I^S | \chi_{c0} \rangle = m_{\chi_{c0}} f_{\chi_{c0}} f_{\chi_{c0}} = 343 MeV [120]
      I^{P} = \bar c i\gamma_5 c 0^+0^{-+} \eta_c 0^+0^{-+} \langle 0 | I^{P} | \eta_c \rangle = \lambda_{\eta_c} \lambda_{\eta_c} = {(f_{\eta_c} m_{\eta_c}^2) / (2 m_c)}
      I^{V}_\mu = \bar c \gamma_\mu c 0^-1^{–} J/\psi 0^-1^{–} \langle0| I^{V}_\mu | J/\psi \rangle = m_{J/\psi} f_{J/\psi} \epsilon_\mu f_{J/\psi} = 418 MeV [121]
      I^{A}_\mu = \bar c \gamma_\mu \gamma_5 c 0^+1^{++} \eta_c 0^+0^{-+} \langle 0 | I^{A}_\mu | \eta_c \rangle = {\rm i} p_\mu f_{\eta_c} f_{\eta_c} = 387 MeV [121]
      \chi_{c1}(1P) 0^+1^{++} \langle 0 | I^{A}_\mu | \chi_{c1} \rangle = m_{\chi_{c1}} f_{\chi_{c1}} \epsilon_\mu f_{\chi_{c1}} = 335 MeV [122]
      I^{T}_{\mu\nu} = \bar c \sigma_{\mu\nu} c 0^-1^{\pm-} J/\psi 0^-1^{–} \langle 0 | I^{T}_{\mu\nu} | J/\psi \rangle = {\rm i} f^T_{J/\psi} (p_\mu\epsilon_\nu - p_\nu\epsilon_\mu) f_{J/\psi}^T = 410 MeV [121]
      h_c(1P) 0^-1^{+-} \langle 0 | I^{T}_{\mu\nu} | h_c \rangle = {\rm i} f^T_{h_c} \epsilon_{\mu\nu\alpha\beta} \epsilon^\alpha p^\beta f_{h_c}^T = 235 MeV [121]
      O^{S} = \bar c q 0^{+} \bar D_0^{*} 0^{+} \langle 0 | O^{S} | \bar D_0^{*} \rangle = m_{D_0^{*}} f_{D_0^{*}} f_{D_0^{*}} = 410 MeV [123]
      O^{P} = \bar c i\gamma_5 q 0^{-} \bar D 0^{-} \langle 0 | O^{P} | \bar D \rangle = \lambda_D \lambda_D = {(f_D m_D^2) / {(m_c + m_d)} }
      O^{V}_\mu = \bar c \gamma_\mu q 1^{-} \bar D^{*} 1^{-} \langle0| O^{V}_\mu | \bar D^{*} \rangle = m_{D^*} f_{D^*} \epsilon_\mu f_{D^*} = 253 MeV [124]
      O^{A}_\mu = \bar c \gamma_\mu \gamma_5 q 1^{+} \bar D 0^{-} \langle 0 | O^{A}_\mu | \bar D \rangle = {\rm i} p_\mu f_{D} f_{D} = 211.9 MeV [2]
      \bar D_1 1^{+} \langle 0 | O^{A}_\mu | \bar D_1 \rangle = m_{D_1} f_{D_1} \epsilon_\mu f_{D_1} = 356 MeV [123]
      O^{T}_{\mu\nu} = \bar c \sigma_{\mu\nu} q 1^{\pm} \bar D^{*} 1^{-} \langle 0 | O^{T}_{\mu\nu} | \bar D^{*} \rangle = {\rm i} f_{D^*}^T (p_\mu\epsilon_\nu - p_\nu\epsilon_\mu) f_{D^*}^T \approx 220 MeV
      1^{+}

      Table 2.  Couplings of meson operators to meson states, where color indices are omitted for simplicity. Taken from Ref. [106].

      \begin{aligned}[b] N = N_1 - N_2 = \epsilon^{abc} (u_a^T \mathbb{C} d_b) \gamma_5 u_c - \epsilon^{abc} (u_a^T \mathbb{C} \gamma_5 d_b) u_c \, . \end{aligned}

      (86)

      This couples to a proton through

      \langle 0 | N | p \rangle = f_p u_p \, ,

      (87)

      with u_p as the Dirac spinor of the proton. The decay constant f_p has been calculated in Ref. [119] to be

      f_p = 0.011 {\rm\; GeV}^3 \, .

      (88)

      To study the decays of the \bar D^{(*)} \Sigma_c^{*} molecular states into charmed mesons and charmed baryons, we must use the \eta(x) and \xi(x) currents. These are constructed in Sec. II by combining charmed meson operators and charmed baryon fields. In the present study, we require the couplings of charmed meson operators to charmed meson states, which are also listed in Table 2. Furthermore, we require couplings of the charmed baryon fields J_{{\cal{B}}} defined in Eq. (16) to the ground-state charmed baryons {\cal{B}} = \Lambda_c/\Sigma_c .

      \langle 0 | J_{{\cal{B}}} | {\cal{B}} \rangle = f_{{\cal{B}}} u_{{\cal{B}}} \, .

      (89)

      Note that we do not investigate the decays of |\bar D^{(*)} \Sigma_c^{*}; J^P\rangle into the \bar D^{(*)} \Sigma_c^* final states in the present study because some J = 3/2 charmed baryon fields still remain unclear [76]. The decay constants f_{{\cal{B}}} have been calculated in Refs. [7779] to be

      \begin{aligned}[b] f_{\Lambda_c} = 0.015 {\rm\; GeV}^3 \, , \quad f_{\Sigma_c} = 0.036 {\rm\; GeV}^3 \, . \end{aligned}

      (90)

      These values are evaluated using the QCD sum rule method [81, 82] within heavy quark effective theory [8385], while the full QCD decay constant f_p for the proton has been given in Eq. (88). These two different schemes cause some, but not significant, theoretical uncertainties.

    • B.   Fierz rearrangement

    • In this subsection, we perform Fierz rearrangement separately for \eta_{4\cdots7} and \xi_{4\cdots7} . The obtained results are used later to study the strong decay properties of the \bar D \Sigma_c^{*} and \bar D^{*} \Sigma_c^{*} molecular states.

      First, however, we note again that Fierz rearrangement in Lorentz space is actually a matrix identity. It is valid if each quark field in the initial and final currents is at the same location, for example, we can apply Fierz rearrangement to transform a non-local current \eta = [\bar c(x) u(x)] \; [u(y) d(y) c(y)] into a combination of many non-local currents \theta = [\bar c(x) c(y)] \; [u(y) d(y) u(x)] with all the quark fields remaining at the same locations. Keeping this in mind, we omit the coordinates in this subsection.

    • 1.   \eta \rightarrow \theta and \xi \rightarrow \theta
    • Using the color rearrangement [76]

      \delta^{ab} \epsilon^{cde} = {1\over3}\; \delta^{ae} \epsilon^{bcd} - {1\over2}\; \lambda^{ae}_n \epsilon^{bcf} \lambda^{fd}_n + {1\over2}\; \lambda^{ae}_n \epsilon^{bdf} \lambda^{fc}_n \, ,

      (91)

      along with Fierz rearrangement to interchange the u_b and c_e quark fields, we can transform an η current into a combination of many θ currents.

      \begin{aligned}[b] \eta_4^\alpha \rightarrow & [\bar c_a \gamma_\mu c_a] \left( - {1\over32} g^{\alpha\mu} - {{\rm i}\over96} \sigma^{\alpha\mu} \right) N \\ & + \; [\bar c_a \gamma_\mu \gamma_5 c_a] \left( - {1\over32} g^{\alpha\mu} \gamma_5 - {{\rm i}\over96} \sigma^{\alpha\mu} \gamma_5 \right) N \\ & + \; [\bar c_a \sigma_{\mu\nu} c_a] \left( {{\rm i}\over48} g^{\alpha\mu}\gamma^\nu + {1\over96} \epsilon^{\alpha\mu\nu\rho} \gamma_\rho \gamma_5 \right) N \\ & + \; \cdots \, , \end{aligned}

      (92)

      \begin{aligned}[b] \eta_5 \rightarrow & + {1\over8} \; [\bar c_a c_a] \; \gamma_5 N + {1\over8} \; [\bar c_a \gamma_5 c_a] \; N \\ & + {1\over16} \; [\bar c_a \gamma_\mu c_a] \; \gamma^\mu \gamma_5 N - {1\over16} \; [\bar c_a \gamma_\mu \gamma_5 c_a] \; \gamma^\mu N \\ & + {1\over48} \; [\bar c_a \sigma_{\mu\nu} c_a] \; \sigma^{\mu\nu} \gamma_5 N + \cdots \, , \\[-10pt]\end{aligned}

      (93)

      \begin{aligned} [b] \eta_6^\alpha \rightarrow & [\bar c_a \gamma_\mu c_a] \left( {3\over32} g^{\alpha\mu} + {{\rm i}\over32} \sigma^{\alpha\mu} \right) N \\ & + \; [\bar c_a \gamma_\mu \gamma_5 c_a] \left( - {3\over32} g^{\alpha\mu} \gamma_5 - {{\rm i}\over32} \sigma^{\alpha\mu} \gamma_5 \right) N + \; \cdots \, , \end{aligned}

      (94)

      \begin{aligned}[b] \eta_7^{\alpha\beta}\rightarrow & \Big( {{\rm i}\over144} \sigma^{\alpha\rho}\epsilon^{\beta\mu\nu\rho} + {1\over72} g^{\alpha\mu}\sigma^{\beta\nu}\gamma_5 - {1\over144} g^{\alpha\beta}\sigma^{\mu\nu}\gamma_5 \Big) \\ & \times \; [\bar c_a \sigma_{\mu\nu} c_a] \; N + \cdots \, . \end{aligned}

      (95)

      In the above expressions, we keep all color-singlet-color-singlet meson-baryon terms depending on the J=1/2 light baryon fields but omit a) the color-octet-color-octet meson-baryon terms, such as [\lambda^{ae}_n \bar c_a c_e][\epsilon^{bcf}\lambda^{fd}_n u_b u_c d_d] , and b) terms depending on the J=3/2 light baryon fields.

      Similarly, we can use Eq. (91) along with Fierz rearrangement to interchange the d_b and c_e quark fields and transform a ξ current into a combination of many θ currents.

      \begin{aligned}[b] \sqrt2 \xi_4^\alpha \rightarrow & [\bar c_a \gamma_\mu c_a] \left( {1\over16} g^{\alpha\mu} + {{\rm i}\over48} \sigma^{\alpha\mu} \right) N \\ & + \; [\bar c_a \gamma_\mu \gamma_5 c_a] \left( {1\over16} g^{\alpha\mu} \gamma_5 + {{\rm i}\over48} \sigma^{\alpha\mu} \gamma_5 \right) N \\ & + \; [\bar c_a \sigma_{\mu\nu} c_a] \left( - {i\over24} g^{\alpha\mu}\gamma^\nu - {1\over48} \epsilon^{\alpha\mu\nu\rho} \gamma_\rho \gamma_5 \right) N \\ & + \; \cdots \, , \\[-5pt]\end{aligned}

      (96)

      \begin{aligned}[b] \sqrt2 \xi_5 \rightarrow & - {1\over4} \; [\bar c_a c_a] \; \gamma_5 N - {1\over4} \; [\bar c_a \gamma_5 c_a] \; N \\ & - {1\over8} \; [\bar c_a \gamma_\mu c_a] \; \gamma^\mu \gamma_5 N + {1\over8} \; [\bar c_a \gamma_\mu \gamma_5 c_a] \; \gamma^\mu N \\ & - {1\over24} \; [\bar c_a \sigma_{\mu\nu} c_a] \; \sigma^{\mu\nu} \gamma_5 N + \cdots \, , \end{aligned}

      (97)

      \begin{aligned}[b] \sqrt2 \xi_6^\alpha \rightarrow & [\bar c_a \gamma_\mu c_a] \left( - {3\over16} g^{\alpha\mu} - {{\rm i}\over16} \sigma^{\alpha\mu} \right) N \\ & + \; [\bar c_a \gamma_\mu \gamma_5 c_a] \left( {3\over16} g^{\alpha\mu} \gamma_5 + {{\rm i}\over16} \sigma^{\alpha\mu} \gamma_5 \right) N \\ & + \; \cdots \, , \end{aligned}

      (98)

      \begin{aligned}[b] \sqrt2 \xi_7^{\alpha\beta} \rightarrow & \Big( - {{\rm i}\over72} \sigma^{\alpha\rho}\epsilon^{\beta\mu\nu\rho} - {1\over36} g^{\alpha\mu}\sigma^{\beta\nu}\gamma_5 \\ & + {1\over72} g^{\alpha\beta}\sigma^{\mu\nu}\gamma_5 \Big) \; [\bar c_a \sigma_{\mu\nu} c_a] \; N + \cdots \, . \end{aligned}

      (99)
    • 2.   \eta \rightarrow \eta and \eta \rightarrow \xi
    • Using the color rearrangement

      \delta^{ab} \epsilon^{cde} = {1\over3}\; \delta^{ac} \epsilon^{bde} - {1\over2}\; \lambda^{ac}_n \epsilon^{bdf} \lambda^{fe}_n + {1\over2}\; \lambda^{ac}_n \epsilon^{bef} \lambda^{fd}_n \, ,

      (100)

      along with Fierz rearrangement to interchange the u_b and u_c quark fields, we can transform an η current into a combination of many η currents.

      Using another color rearrangement

      \begin{aligned}[b] \delta^{ab} \epsilon^{cde} =& {1\over3}\; \delta^{ad} \epsilon^{cbe} + {1\over2}\; \lambda^{ad}_n \epsilon^{bcf} \lambda^{fe}_n \\&- {1\over2}\; \lambda^{ad}_n \epsilon^{bef} \lambda^{fc}_n \, , \end{aligned}

      (101)

      along with Fierz rearrangement to interchange the u_b and d_d quark fields, we can transform an η current into a combination of many ξ currents.

      Overall, we obtain

      \begin{aligned}[b] \eta_4^\alpha \rightarrow & \left( {1\over16}g^{\alpha\mu} + {{\rm i}\over48}\sigma^{\alpha\mu} \right) \; [\bar c_a \gamma_\mu u_a] \; \Lambda_c^+ \\ &+ \left( {{\rm i}\over384}\sigma^{\alpha\sigma} \epsilon^{\mu\nu\rho\sigma} - {1\over128}\epsilon^{\alpha\mu\nu\rho} \right) [\bar c_a \sigma_{\mu\nu} u_a] \gamma_\rho \gamma_5 \Sigma_c^+ \\ &+ \left( {{\rm i}\sqrt2\over384}\sigma^{\alpha\sigma} \epsilon^{\mu\nu\rho\sigma} - {\sqrt2\over128}\epsilon^{\alpha\mu\nu\rho} \right) \\ & \times \; [\bar c_a \sigma_{\mu\nu} d_a] \; \gamma_\rho \gamma_5 \Sigma_c^{++} + \cdots \, , \end{aligned}

      (102)

      \begin{aligned}[b] \eta_5 \rightarrow & - {1\over4} \; [\bar c_a \gamma_5 u_a] \; \Lambda_c^+ - {1\over48} \; [\bar c_a \sigma_{\mu\nu} u_a] \; \sigma^{\mu\nu}\gamma_5 \Lambda_c^+ \\ & - {1\over32} \; [\bar c_a \gamma_\mu u_a] \; \gamma^\mu \gamma_5 \Sigma_c^+ + {1\over32} \; [\bar c_a \gamma_\mu \gamma_5 u_a] \; \gamma^\mu \Sigma_c^+ \\ & - {\sqrt2\over32} [\bar c_a \gamma_\mu d_a] \gamma^\mu \gamma_5 \Sigma_c^{++} + {\sqrt2\over32} [\bar c_a \gamma_\mu \gamma_5 d_a] \gamma^\mu \Sigma_c^{++} \\ & + \; \cdots \, , \end{aligned}

      (103)

      \begin{aligned}[b] \eta_6^\alpha \rightarrow & \left( {{\rm i}\over16}g^{\alpha\mu}\gamma^\nu + {1\over32}\epsilon^{\alpha\mu\nu\rho}\gamma_\rho\gamma_5 \right) \; [\bar c_a \sigma_{\mu\nu} u_a] \; \Lambda_c^+ \\ &+ \left( {1\over96}g^{\alpha\mu}\gamma^\nu\gamma_5 + {1\over96}g^{\alpha\nu}\gamma^\mu\gamma_5 - {1\over192}g^{\mu\nu}\gamma^\alpha\gamma_5 \right) \\ & \times \; [\bar c_a \gamma_\mu u_a] \; \gamma_\nu \gamma_5 \Sigma_c^+ \\ &+ \left( {1\over64}g^{\alpha\mu}\gamma^\nu - {1\over64}g^{\alpha\nu}\gamma^\mu - {{\rm i}\over64}\epsilon^{\alpha \mu \nu \rho}\gamma_\rho\gamma_5 \right) \\ & \times \; [\bar c_a \gamma_\mu \gamma_5 u_a] \; \gamma_\nu \gamma_5 \Sigma_c^+ \\ &+ \left( {\sqrt2\over96}g^{\alpha\mu}\gamma^\nu\gamma_5 + {\sqrt2\over96}g^{\alpha\nu}\gamma^\mu\gamma_5 - {\sqrt2\over192}g^{\mu\nu}\gamma^\alpha\gamma_5 \right) \\ & \times \; [\bar c_a \gamma_\mu d_a] \; \gamma_\nu \gamma_5 \Sigma_c^{++} \\ &+ \left( {\sqrt2\over64}g^{\alpha\mu}\gamma^\nu - {\sqrt2\over64}g^{\alpha\nu}\gamma^\mu - {{\rm i}\sqrt2\over64}\epsilon^{\alpha \mu \nu \rho}\gamma_\rho\gamma_5 \right) \\ &\times \; [\bar c_a \gamma_\mu \gamma_5 d_a] \; \gamma_\nu \gamma_5 \Sigma_c^{++} + \cdots \, , \end{aligned}

      (104)

      \begin{aligned}[b] \eta_7^{\alpha\beta} \rightarrow & \Big( {1\over36}g^{\alpha\mu}g^{\beta\nu} - {1\over144}g^{\alpha\beta}g^{\mu\nu} + {{\rm i}\over144}g^{\alpha\mu}\sigma^{\beta\nu} \\ & + {{\rm i}\over144}g^{\alpha\nu}\sigma^{\beta\mu} \Big) \; [\bar c_a \gamma_\mu u_a] \; \gamma_\nu \gamma_5 \Sigma_c^+ \\ &+ \Big( {\sqrt2\over36}g^{\alpha\mu}g^{\beta\nu} - {\sqrt2\over144}g^{\alpha\beta}g^{\mu\nu} + {{\rm i}\sqrt2\over144}g^{\alpha\mu}\sigma^{\beta\nu} \\ &+ {{\rm i}\sqrt2\over144}g^{\alpha\nu}\sigma^{\beta\mu} \Big) \; [\bar c_a \gamma_\mu d_a] \; \gamma_\nu \gamma_5 \Sigma_c^{++} + \cdots \, . \end{aligned}

      (105)

      In the above expressions, we keep all color-singlet-color-singlet meson-baryon terms depending on the J^P=1/2^+ charmed baryon fields, that is, J_{\Lambda_c^+} and J_{\Sigma_c^{+/++}} defined in Eqs. (16). However, we omit a) the color-octet-color-octet meson-baryon terms and b) terms depending on the J=3/2 charmed baryon fields.

    • 3.   \xi \rightarrow \eta
    • Using Eqs. (100) and (101) along with Fierz rearrangement in Lorentz space, we can transform a ξ current into a combination of many η currents (but without ξ currents).

      \begin{aligned}[b] \sqrt2 \xi_4^\alpha \rightarrow & \left( - {1\over8}g^{\alpha\mu} - {{\rm i}\over24}\sigma^{\alpha\mu} \right) \; [\bar c_a \gamma_\mu u_a] \; \Lambda_c^+ \\ &+ \left( {{\rm i}\over192}\sigma^{\alpha\sigma} \epsilon^{\mu\nu\rho\sigma} - {1\over64}\epsilon^{\alpha\mu\nu\rho} \right) \\ & \times \; [\bar c_a \sigma_{\mu\nu} u_a] \; \gamma_\rho \gamma_5 \Sigma_c^+ + \cdots \, , \end{aligned}

      (106)

      \begin{aligned}[b] \sqrt2 \xi_5 \rightarrow & + {1\over2} \; [\bar c_a \gamma_5 u_a] \; \Lambda_c^+ + {1\over24} \; [\bar c_a \sigma_{\mu\nu} u_a] \; \sigma^{\mu\nu}\gamma_5 \Lambda_c^+ \\ & - {1\over16} [\bar c_a \gamma_\mu u_a] \gamma^\mu \gamma_5 \Sigma_c^+ + {1\over16} [\bar c_a \gamma_\mu \gamma_5 u_a] \gamma^\mu \Sigma_c^+ \\ & + \; \cdots \, , \\[-10pt]\end{aligned}

      (107)

      \begin{aligned}[b] \sqrt2 \xi_6^\alpha \rightarrow & \left( - {{\rm i}\over8}g^{\alpha\mu}\gamma^\nu - {1\over16}\epsilon^{\alpha\mu\nu\rho}\gamma_\rho\gamma_5 \right) \; [\bar c_a \sigma_{\mu\nu} u_a] \; \Lambda_c^+ \\ &+ \left( {1\over48}g^{\alpha\mu}\gamma^\nu\gamma_5 + {1\over48}g^{\alpha\nu}\gamma^\mu\gamma_5 - {1\over96}g^{\mu\nu}\gamma^\alpha\gamma_5 \right) \\ & \times \; [\bar c_a \gamma_\mu u_a] \; \gamma_\nu \gamma_5 \Sigma_c^+ \\ &+ \left( {1\over32}g^{\alpha\mu}\gamma^\nu - {1\over32}g^{\alpha\nu}\gamma^\mu - {{\rm i}\over32}\epsilon^{\alpha \mu \nu \rho}\gamma_\rho\gamma_5 \right) \\ & \times \; [\bar c_a \gamma_\mu \gamma_5 u_a] \; \gamma_\nu \gamma_5 \Sigma_c^+ + \cdots \, , \end{aligned}

      (108)

      \begin{aligned}[b] \sqrt2 \xi_7^{\alpha\beta} \rightarrow & \Big( {1\over18}g^{\alpha\mu}g^{\beta\nu} - {1\over72}g^{\alpha\beta}g^{\mu\nu} + {{\rm i}\over72}g^{\alpha\mu}\sigma^{\beta\nu} \\ & + {{\rm i}\over72}g^{\alpha\nu}\sigma^{\beta\mu} \Big) \; [\bar c_a \gamma_\mu u_a] \; \gamma_\nu \gamma_5 \Sigma_c^+ + \cdots \, . \end{aligned}

      (109)
    • C.   Decay analyses

    • Based on the Fierz rearrangements derived in the previous subsection, we now study the strong decay properties of the \bar D^{(*)0} \Sigma_c^{*+} and D^{(*)-} \Sigma_c^{*++} molecular states. As an example, we first investigate |\bar D^0 \Sigma_c^{*+}; 3/2^- \rangle through the \eta_4 current and Fierz rearrangements given in Eqs. (92) and (102). Others are similarly investigated. The obtained results are combined in Sec. V.D to further study the \bar D^{(*)} \Sigma_c^* molecular states of I=1/2 .

    • 1.   \eta_4 \rightarrow \theta / \eta / \xi
    • As an example, we investigate |\bar D^0 \Sigma_c^{*+}; 3/2^- \rangle through the \eta_4 current and Fierz rearrangements given in Eqs. (97) and (107).

      First, we study Eq. (92). As depicted in Fig. 5(a), when the \bar c_a and c_e quarks meet and the other three quarks meet simultaneously, |\bar D^0 \Sigma_c^{*+}; 3/2^- \rangle can decay into one charmonium meson and one light baryon.

      Figure 5.  (color online) Fall-apart decays of the \bar D^{(*)0} \Sigma_c^{(*)+} molecular states investigated using the η currents. There are three possible decay processes: a) \eta \rightarrow \theta, b) \eta \rightarrow \eta, and c) \eta \rightarrow \xi. Their probabilities are the same (33%) if only considering the color degree of freedom. Taken from Ref. [76].

      \begin{aligned}[b] &\;\; \left[\delta^{ab} \bar c_a u_b\right] \; \left[\epsilon^{cde} u_c d_d c_e\right] \\ \underline{\underline {{\rm{color}}}} &\;\; {1\over3}\delta^{ae} \epsilon^{bcd} \; \bar c_au_b \; u_c d_d c_e + \cdots \\ \underline{\underline {{\rm{Fierz}}}} &\;\; {1\over3} \; \left[\delta^{ae}\bar c_a c_e\right] \; \left[\epsilon^{bcd} u_c d_d u_b\right] + \cdots . \end{aligned}

      (110)

      In particular, we must apply Fierz rearrangement in the first and third steps to interchange both the color and Dirac indices of the u_b and c_e quark fields.

      The above decay process can be described by the Fierz rearrangement given in Eq. (92), from which we extract the following two decay channels that are kinematically allowed:

      1. The decay of |\bar D^0 \Sigma_c^{*+}; 3/2^- \rangle into \eta_c p is contributed by [\bar c_a \gamma_\mu \gamma_5 c_a]N .

      \begin{aligned}[b] & \langle \bar D^0 \Sigma_c^{*+}; 3/2^-(q) \; |\; \eta_c(q_1)\; p(q_2) \rangle \\ \approx& {a_4}\; {\rm i} f_{\eta_c} f_p q_1^\mu \; \bar u^\alpha \left( - {1\over32} g_{\alpha\mu} \gamma_5 - {{\rm i}\over96} \sigma_{\alpha\mu} \gamma_5 \right) u_p \, , \end{aligned}

      (111)

      where u_\alpha and u_p are spinors of |\bar D^0 \Sigma_c^{*+}; 3/2^- \rangle and the proton, respectively. a_4 is an overall factor related to the coupling of \eta_4 to |\bar D^0 \Sigma_c^{*+}; 3/2^- \rangle and the dynamical process of Fig. 5(a).

      2. The decay of |\bar D^0 \Sigma_c^{*+}; 3/2^- \rangle into J/\psi p is contributed by both [\bar c_a \gamma_\mu c_a]N and [\bar c_a \sigma_{\mu\nu} c_a]N .

      \begin{aligned}[b] & \langle \bar D^0 \Sigma_c^{*+}; 3/2^-(q) | J/\psi(q_1,\epsilon_1)\; p(q_2) \rangle \\ \approx& {a_4}\; m_{J/\psi} f_{J/\psi} f_p \epsilon_1^\mu \; \bar u^\alpha \left( - {1\over32} g_{\alpha\mu} - {{\rm i}\over96} \sigma_{\alpha\mu} \right) u_p \\ &+ {a_4}\; {\rm i}f^T_{J/\psi} f_p \; \left(q_1^\mu \epsilon_1^\nu - q_1^\nu \epsilon_1^\mu \right) \\ &\times \bar u^\alpha \left( {{\rm i}\over48} g_{\alpha\mu}\gamma_\nu + {1\over96} \epsilon_{\alpha\mu\nu\rho} \gamma^\rho \gamma_5 \right) u_p \, . \end{aligned}

      (112)

      Subsequently, we study Eq. (102). As depicted in Fig. 5(b), when the \bar c_a and u_c quarks meet and the other three quarks meet simultaneously, |\bar D^0 \Sigma_c^{*+}; 3/2^- \rangle can decay into one charmed meson and one charmed baryon. Similarly, we can study the decay process depicted in Fig. 5(c). These two processes can be described by the Fierz rearrangement given in Eq. (102), from which we extract only one decay channel that is kinematically allowed:

      3. The decay of |\bar D^0 \Sigma_c^{*+}; 3/2^- \rangle into \bar D^{*0} \Lambda_c^+ is contributed by [\bar c_a \gamma_\mu u_a]\Lambda_c^+ :

      \begin{aligned}[b] & \langle \bar D^0 \Sigma_c^{*+}; 3/2^-(q) \; |\; \bar D^{*0}(q_1,\epsilon_1)\; \Lambda_c^+(q_2) \rangle \\ \approx& {b_4}\; m_{D^*} f_{D^*} f_{\Lambda_c} \epsilon_1^\mu \; \bar u^\alpha \left( {1\over16}g_{\alpha\mu} + {{\rm i}\over48}\sigma_{\alpha\mu} \right) u_{\Lambda_c} \, , \end{aligned}

      (113)

      where u_{\Lambda_c} is the Dirac spinor of \Lambda_c^+ . b_4 is an overall factor related to the coupling of \eta_4 to |\bar D^0 \Sigma_c^{*+}; 3/2^- \rangle and the dynamical processes of Fig. 5(b, c).

      Assuming the mass of |\bar D^0 \Sigma_c^{*+}; 3/2^- \rangle to be approximately M_{D} + M_{\Sigma_c^*} \approx 4385 MeV, we summarize the above decay amplitudes to obtain the following partial decay widths:

      \begin{aligned}[b] \Gamma(|\bar D^0 \Sigma_c^{*+}; 3/2^- \rangle \to \eta_c p ) =& a_4^2 \; 42 \; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^0 \Sigma_c^{*+}; 3/2^- \rangle \to J/\psi p ) =& a_4^2 \; 60 \; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^0 \Sigma_c^{*+}; 3/2^- \rangle \to \bar D^{*0} \Lambda_c^+ ) =& b_4^2 \; 1.5 \times 10^{4}\; {\rm{GeV}}^7 \, . \end{aligned}

      (114)

      There are two different terms, A \equiv [\bar c_a \gamma_\mu c_a]N and B \equiv [\bar c_a \sigma_{\mu\nu} c_a]N , both of which can contribute to the decay of |\bar D^0 \Sigma_c^{*+}; 3/2^- \rangle into J/\psi p . Their individual contributions are

      \begin{aligned}[b] \Gamma(|\bar D^0 \Sigma_c^{*+}; 3/2^- \rangle \to J/\psi p )\big|_A =& a_4^2 \; 1.0 \times 10^{4}\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^0 \Sigma_c^{*+}; 3/2^- \rangle \to J/\psi p )\big|_B =& a_4^2 \; 1.1 \times 10^{4}\; {\rm{GeV}}^7 \, . \end{aligned}

      (115)

      Hence, their contributions are at the same level but almost cancel each other out, suggesting that their interference is important. However, the phase angle between them, that is, the phase angle between the two coupling constants f_{J/\psi} and f_{J/\psi}^T , cannot be well determined in the present study. We investigate its relevant (theoretical) uncertainty in Appendix B.

    • 2.   \xi_4 \rightarrow \theta / \eta
    • To study |D^{-} \Sigma_c^{*++}; 3/2^- \rangle , we use the \xi_4 current and Fierz rearrangements given in Eqs. (96) and (106). Assuming its mass to be the same as that of |\bar D^{0} \Sigma_c^{*+}; 3/2^- \rangle , we obtain the following partial decay widths:

      \begin{aligned}[b] \Gamma(|D^- \Sigma_c^{*++}; 3/2^- \rangle \to \eta_c p ) =& a_4^2 \; 84 \; {\rm{GeV}}^7 \, , \\ \Gamma(|D^- \Sigma_c^{*++}; 3/2^- \rangle \to J/\psi p ) =& a_4^2 \; 120 \; {\rm{GeV}}^7 \, , \\ \Gamma(|D^- \Sigma_c^{*++}; 3/2^- \rangle \to \bar D^{*0} \Lambda_c^+ ) =& b_4^2 \; 3.0 \times 10^{4}\; {\rm{GeV}}^7 \, . \end{aligned}

      (116)

      Here, we use the same overall factors a_4 and b_4 as those for the \eta_4 current.

    • 3.   \eta_5 \rightarrow \theta / \eta / \xi
    • To study |\bar D^{*0} \Sigma_c^{*+}; 1/2^- \rangle , we use the \eta_5 current and Fierz rearrangements given in Eqs. (93) and (103). Assuming its mass to be approximately M_{D^*} + M_{\Sigma_c^*} \approx 4527 MeV, we obtain the following partial decay widths:

      \begin{aligned}[b] \Gamma(|\bar D^{*0} \Sigma_c^{*+}; 1/2^- \rangle \to \eta_c p ) =& a_5^2 \; 3.3 \times 10^{5} \; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*0} \Sigma_c^{*+}; 1/2^- \rangle \to J/\psi p ) =& a_5^2 \; 1.0 \times 10^{4} \; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*0} \Sigma_c^{*+}; 1/2^- \rangle \to \chi_{c0} p ) =& a_5^2 \; 3.2 \times 10^{3} \; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*0} \Sigma_c^{*+}; 1/2^- \rangle \to \chi_{c1} p ) =& a_5^2 \; 1.1 \times 10^{3} \; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*0} \Sigma_c^{*+}; 1/2^- \rangle \to h_{c} p ) =& a_5^2 \; 220 \; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*0} \Sigma_c^{*+}; 1/2^- \rangle \to \bar D^{0} \Lambda_c^+ ) =& b_5^2 \; 3.5 \times 10^{5}\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*0} \Sigma_c^{*+}; 1/2^- \rangle \to \bar D^{*0} \Lambda_c^+ ) =& b_5^2 \; 1.6 \times 10^{4}\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*0} \Sigma_c^{*+}; 1/2^- \rangle \to \bar D^{0} \Sigma_c^+ )=& b_5^2 \; 1.4 \times 10^{4}\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*0} \Sigma_c^{*+}; 1/2^- \rangle \to D^- \Sigma_c^{++} ) =& b_5^2 \; 2.9 \times 10^{4}\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*0} \Sigma_c^{*+}; 1/2^- \rangle \to \bar D^{*0} \Sigma_c^+ ) =& b_5^2 \; 3.3 \times 10^{4}\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*0} \Sigma_c^{*+}; 1/2^- \rangle \to D^{*-} \Sigma_c^{++} ) =& b_5^2 \; 6.6 \times 10^{4}\; {\rm{GeV}}^7 \, , \end{aligned}

      (117)

      where a_5 and b_5 are two overall factors.

    • 4.   \xi_5 \rightarrow \theta / \eta
    • To study |D^{*-} \Sigma_c^{*++}; 1/2^- \rangle , we use the \xi_5 current and the Fierz rearrangements given in Eqs. (97) and (107). Assuming its mass to be the same as that of |\bar D^{*0} \Sigma_c^{*+}; 1/2^- \rangle , we obtain the following partial decay widths:

      \begin{aligned}[b] \Gamma(|D^{*-} \Sigma_c^{*++}; 1/2^- \rangle \to \eta_c p ) =& a_5^2 \; 6.5 \times 10^{5} \; {\rm{GeV}}^7 \, , \\ \Gamma(|D^{*-} \Sigma_c^{*++}; 1/2^- \rangle \to J/\psi p ) =& a_5^2 \; 2.1 \times 10^{4} \; {\rm{GeV}}^7 \, , \\ \Gamma(|D^{*-} \Sigma_c^{*++}; 1/2^- \rangle \to \chi_{c0} p ) =& a_5^2 \; 6.4 \times 10^{3} \; {\rm{GeV}}^7 \, , \\ \Gamma(|D^{*-} \Sigma_c^{*++}; 1/2^- \rangle \to \chi_{c1} p ) =& a_5^2 \; 2.1 \times 10^{3} \; {\rm{GeV}}^7 \, , \\ \Gamma(|D^{*-} \Sigma_c^{*++}; 1/2^- \rangle \to h_{c} p ) =& a_5^2 \; 450 \; {\rm{GeV}}^7 \, , \\ \Gamma(|D^{*-} \Sigma_c^{*++}; 1/2^- \rangle \to \bar D^{0} \Lambda_c^+ ) =& b_5^2 \; 7.0 \times 10^{5}\; {\rm{GeV}}^7 \, , \\ \Gamma(|D^{*-} \Sigma_c^{*++}; 1/2^- \rangle \to \bar D^{*0} \Lambda_c^+ ) =& b_5^2 \; 3.1 \times 10^{4}\; {\rm{GeV}}^7 \, , \\ \Gamma(|D^{*-} \Sigma_c^{*++}; 1/2^- \rangle \to \bar D^{0} \Sigma_c^+ ) =& b_5^2 \; 2.9 \times 10^{4}\; {\rm{GeV}}^7 \, , \\ \Gamma(|D^{*-} \Sigma_c^{*++}; 1/2^- \rangle \to \bar D^{*0} \Sigma_c^+ ) =& b_5^2 \; 6.6 \times 10^{4}\; {\rm{GeV}}^7 \, . \end{aligned}

      (118)
    • 5.   \eta_6 \rightarrow \theta / \eta / \xi
    • To study |\bar D^{*0} \Sigma_c^{*+}; 3/2^- \rangle , we use the \eta_6 current and Fierz rearrangements given in Eqs. (94) and (104). Assuming its mass to be the same as that of |\bar D^{*0} \Sigma_c^{*+}; 1/2^- \rangle , we obtain the following partial decay widths:

      \begin{aligned}[b] \Gamma(|\bar D^{*0} \Sigma_c^{*+}; 3/2^- \rangle \to \eta_c p ) =& a_6^2 \; 750 \; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*0} \Sigma_c^{*+}; 3/2^- \rangle \to J/\psi p ) =& a_6^2 \; 1.2 \times 10^{5} \; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*0} \Sigma_c^{*+}; 3/2^- \rangle \to \chi_{c0} p ) =& a_6^2 \; 960 \; {\rm{GeV}}^7 \, ,\\ \Gamma(|\bar D^{*0} \Sigma_c^{*+}; 3/2^- \rangle \to \bar D^{*0} \Lambda_c^+ )=& b_6^2 \; 4.5 \times 10^{4}\; {\rm{GeV}}^7 \, , \\ \end{aligned}

      \begin{aligned}[b] \Gamma(|\bar D^{*0} \Sigma_c^{*+}; 3/2^- \rangle \to \bar D^{0} \Sigma_c^+ ) =& b_6^2 \; 36\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*0} \Sigma_c^{*+}; 3/2^- \rangle \to D^- \Sigma_c^{++} ) =& b_6^2 \; 71\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*0} \Sigma_c^{*+}; 3/2^- \rangle \to \bar D^{*0} \Sigma_c^+ ) =& b_6^2 \; 4.3 \times 10^{4}\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*0} \Sigma_c^{*+}; 3/2^- \rangle \to D^{*-} \Sigma_c^{++} ) =& b_6^2 \; 8.7 \times 10^{4}\; {\rm{GeV}}^7 \, , \end{aligned}

      (119)

      where a_6 and b_6 are two overall factors.

    • 6.   \xi_6 \rightarrow \theta / \eta
    • To study |D^{*-} \Sigma_c^{*++}; 3/2^- \rangle , we use the \xi_6 current and Fierz rearrangements given in Eqs. (98) and (108). Assuming its mass to be the same as that of |\bar D^{*0} \Sigma_c^{*+}; 1/2^- \rangle , we obtain the following partial decay widths:

      \begin{aligned}[b] \Gamma(|D^{*-} \Sigma_c^{*++}; 3/2^- \rangle \to \eta_c p ) =& a_6^2 \; 1.5 \times 10^{3} \; {\rm{GeV}}^7 \, , \\ \Gamma(|D^{*-} \Sigma_c^{*++}; 3/2^- \rangle \to J/\psi p ) =& a_6^2 \; 2.3 \times 10^{5} \; {\rm{GeV}}^7 \, , \\ \Gamma(|D^{*-} \Sigma_c^{*++}; 3/2^- \rangle \to \chi_{c0} p ) =& a_6^2 \; 1.9 \times 10^{3} \; {\rm{GeV}}^7 \, , \\ \Gamma(|D^{*-} \Sigma_c^{*++}; 3/2^- \rangle \to \bar D^{*0} \Lambda_c^+ ) =& b_6^2 \; 9.1 \times 10^{4}\; {\rm{GeV}}^7 \, , \\ \Gamma(|D^{*-} \Sigma_c^{*++}; 3/2^- \rangle \to \bar D^{0} \Sigma_c^+ ) =& b_6^2 \; 71\; {\rm{GeV}}^7 \, , \\ \Gamma(|D^{*-} \Sigma_c^{*++}; 3/2^- \rangle \to \bar D^{*0} \Sigma_c^+ ) =& b_6^2 \; 8.7 \times 10^{4}\; {\rm{GeV}}^7 \, . \end{aligned}

      (120)
    • 7.   \eta_7 \rightarrow \theta / \eta / \xi and \xi_7 \rightarrow \theta / \eta
    • To study |\bar D^{*0} \Sigma_c^{*+}; 5/2^- \rangle , we use the \eta_7 current and Fierz rearrangements given in Eqs. (95) and (105); however, we do not obtain any non-zero decay channels. This state probably mainly decays into spin-1 mesons and spin-3/2 baryons, such as J/\psi N^* and D^* \Sigma_c^* . However, these final states are not investigated in the present study. The same results are obtained for |D^{*-} \Sigma_c^{*++}; 5/2^- \rangle .

    • D.   Isospin analyses

    • In this subsection, we collect the results calculated in the previous subsection to further study the decay properties of the \bar D^{(*)} \Sigma_c^* molecular states with I=1/2 .

      Combining the results of Sec. V.C.1 and Sec. V.C.2, we obtain the following partial decay widths for |\bar D \Sigma_c^{*}; 3/2^- \rangle of I=1/2 :

      \begin{aligned}[b] \Gamma(|\bar D \Sigma_c^{*}; 3/2^- \rangle \to \eta_c p ) =& a_4^2 \; 130 \; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D \Sigma_c^{*}; 3/2^- \rangle \to J/\psi p ) =& a_4^2 \; 180 \; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D \Sigma_c^{*}; 3/2^- \rangle \to \bar D^{*0} \Lambda_c^+ ) =& b_4^2 \; 4.5 \times 10^{4}\; {\rm{GeV}}^7 \, . \end{aligned}

      (121)

      Combining the results of Sec. V.C.3 and Sec. V.C.4, we obtain the following partial decay widths for |\bar D^* \Sigma_c^{*}; 1/2^- \rangle of I=1/2 :

      \begin{aligned}[b] \Gamma(|\bar D^{*} \Sigma_c^{*}; 1/2^- \rangle \to \eta_c p ) =a_5^2 \; 9.8 \times 10^{5} \; {\rm{GeV}}^7 \, , \end{aligned}

      \begin{aligned}[b] \Gamma(|\bar D^{*} \Sigma_c^{*}; 1/2^- \rangle \to J/\psi p ) =& a_5^2 \; 3.1 \times 10^{4} \; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c^{*}; 1/2^- \rangle \to \chi_{c0} p ) =& a_5^2 \; 9.5 \times 10^{3} \; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c^{*}; 1/2^- \rangle \to \chi_{c1} p ) =& a_5^2 \; 3.2 \times 10^{3} \; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c^{*}; 1/2^- \rangle \to h_{c} p ) =& a_5^2 \; 670 \; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c^{*}; 1/2^- \rangle \to \bar D^{0} \Lambda_c^+ ) =& b_5^2 \; 1.1 \times 10^{6}\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c^{*}; 1/2^- \rangle \to \bar D^{*0} \Lambda_c^+ ) =& b_5^2 \; 4.7 \times 10^{4}\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c^{*}; 1/2^- \rangle \to \bar D^{0} \Sigma_c^+ ) =& b_5^2 \; 4.8 \times 10^{3}\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c^{*}; 1/2^- \rangle \to D^- \Sigma_c^{++} ) =& b_5^2 \; 9.6 \times 10^{3}\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c^{*}; 1/2^- \rangle \to \bar D^{*0} \Sigma_c^+ ) =& b_5^2 \; 1.1 \times 10^{4}\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c^{*}; 1/2^- \rangle \to D^{*-} \Sigma_c^{++} ) =& b_5^2 \; 2.2 \times 10^{4}\; {\rm{GeV}}^7 \, . \end{aligned}

      (122)

      Combining the results of Sec. V.C.5 and Sec. V.C.6, we obtain the following partial decay widths for |\bar D^* \Sigma_c^{*}; 3/2^- \rangle of I=1/2 :

      \begin{aligned}[b] \Gamma(|\bar D^{*} \Sigma_c^{*}; 3/2^- \rangle \to \eta_c p ) =& a_6^2 \; 2.2 \times 10^{3} \; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c^{*}; 3/2^- \rangle \to J/\psi p ) =& a_6^2 \; 3.5 \times 10^{5} \; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c^{*}; 3/2^- \rangle \to \chi_{c0} p ) =& a_6^2 \; 2.9 \times 10^{3} \; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c^{*}; 3/2^- \rangle \to \bar D^{*0} \Lambda_c^+ ) =& b_6^2 \; 1.4 \times 10^{5}\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c^{*}; 3/2^- \rangle \to \bar D^{0} \Sigma_c^+ ) =& b_6^2 \; 12\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c^{*}; 3/2^- \rangle \to D^- \Sigma_c^{++} ) =& b_6^2 \; 24\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c^{*}; 3/2^- \rangle \to \bar D^{*0} \Sigma_c^+ ) =& b_6^2 \; 1.4 \times 10^{4}\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c^{*}; 3/2^- \rangle \to D^{*-} \Sigma_c^{++} ) =& b_6^2 \; 2.9 \times 10^{4}\; {\rm{GeV}}^7 \, . \end{aligned}

      (123)

      We do not obtain any non-zero decay channels for |\bar D^* \Sigma_c^{*}; 5/2^- \rangle of I=1/2 . This state probably mainly decays into spin-1 mesons and spin-3/2 baryons, such as J/\psi N^* and \bar D^* \Sigma_c^* . However, these final states are not investigated in the present study.

      The decay properties of the \bar D^{(*)} \Sigma_c molecular states havebeen investigated in Ref. [76], including |\bar D \Sigma_c; 1/2^- \rangle , |\bar D^{*} \Sigma_c; 1/2^- \rangle , and |\bar D^{*} \Sigma_c; 3/2^- \rangle . There, we used them to explain P_c(4312)^+ , P_c(4440)^+ , and P_c(4457)^+ , respectively. However, we find that P_c(4440)^+ and P_c(4457)^+ can be better interpreted in our framework as |\bar D^{*} \Sigma_c; 3/2^- \rangle and |\bar D^{*} \Sigma_c; 1/2^- \rangle , respectively/inversely.

      Accordingly, we assume the masses of |\bar D \Sigma_c; 1/2^- \rangle , |\bar D^{*} \Sigma_c; 1/2^- \rangle , and |\bar D^{*} \Sigma_c; 3/2^- \rangle to be M_{P_c(4312)^+} = 4311.9 MeV, M_{P_c(4457)^+} = 4457.3 MeV, and M_{P_c(4440)^+} = 4440.3 MeV, respectively. Recalculations are performed, and we summarize the results here. Note that a) some errors were detected in the results of Ref. [76] when calculating \Gamma(|\bar D^* \Sigma_c; 1/2^- \rangle \to J/\psi p) , and b) different notations are used here for the overall factors.

      For |\bar D \Sigma_c; 1/2^- \rangle of I=1/2 , we find

      \begin{aligned}[b] \Gamma(|\bar D \Sigma_c; 1/2^- \rangle \to \eta_c p ) =a_1^2 \; 3.2 \times 10^{5}\; {\rm{GeV}}^7 \, , \end{aligned}

      \begin{aligned}[b] \Gamma(|\bar D \Sigma_c; 1/2^- \rangle \to J/\psi p ) =& a_1^2 \; 8.5 \times 10^{4}\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D \Sigma_c; 1/2^- \rangle \to \bar D^{*0} \Lambda_c^+ ) =& b_1^2 \; 5.9 \times 10^{4}\; {\rm{GeV}}^7 \, . \end{aligned}

      (124)

      For |\bar D^{*} \Sigma_c; 1/2^- \rangle of I=1/2 , we find

      \begin{aligned}[b] \Gamma(|\bar D^{*} \Sigma_c; 1/2^- \rangle \to \eta_c p ) =& a_2^2 \; 1.8 \times 10^{5}\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c; 1/2^- \rangle \to J/\psi p ) =& a_2^2 \; 5.1 \times 10^{5}\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c; 1/2^- \rangle \to \chi_{c0} p ) =& a_2^2 \; 8.0 \times 10^{3}\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c; 1/2^- \rangle \to \chi_{c1} p ) =& a_2^2 \; 200\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c; 1/2^- \rangle \to \bar D^{0} \Lambda_c^+ ) =& b_2^2 \; 1.7 \times 10^{6}\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c; 1/2^- \rangle \to \bar D^{*0} \Lambda_c^+ ) =& b_2^2 \; 6.0 \times 10^{5}\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c; 1/2^- \rangle \to \bar D^{0} \Sigma_c^+ ) =& b_2^2 \; 5.9 \times 10^{4}\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c; 1/2^- \rangle \to D^- \Sigma_c^{++} ) =& b_2^2 \; 1.2 \times 10^{5}\; {\rm{GeV}}^7 \, . \end{aligned}

      (125)

      For |\bar D^{*} \Sigma_c; 3/2^- \rangle of I=1/2 , we find

      \begin{aligned}[b] \Gamma(|\bar D^{*} \Sigma_c; 3/2^- \rangle \to \eta_c p ) =& a_3^2 \; 670\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c; 3/2^- \rangle \to J/\psi p ) =& a_3^2 \; 1.4 \times 10^{5}\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c; 3/2^- \rangle \to \bar D^{*0} \Lambda_c^+ ) =& b_3^2 \; 4.6 \times 10^{4}\; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c; 3/2^- \rangle \to \bar D^{0} \Sigma_c^+ ) =& b_3^2 \; 1.4 \; {\rm{GeV}}^7 \, , \\ \Gamma(|\bar D^{*} \Sigma_c; 3/2^- \rangle \to D^- \Sigma_c^{++} ) =& b_3^2 \; 2.7 \; {\rm{GeV}}^7 \, . \end{aligned}

      (126)

      We use the above partial decay widths to further derive their corresponding relative branching ratios. The obtained results are summarized in Table 3, where a new parameter t \equiv {b_i^2 / a_i^2} ( i=1\cdots7 ) is introduced to measure which processes occur more easily, the process depicted in Fig. 5(a) or the processes depicted in Fig. 5(b, c). We discuss these results in Sec. VI.

      ConfigurationDecay channelsProductions
      J/\psi p\eta_c p\chi_{c0} p\chi_{c1} ph_c p\bar D^{0} \Lambda_c^+\bar D^{*0} \Lambda_c^+\bar D^{0} \Sigma_c^+D^{-} \Sigma_c^{++}\bar D^{*0} \Sigma_c^+D^{*-} \Sigma_c^{++}{\cal{R}}_1{\cal{R}}_2
      |\bar D \Sigma_c; 1/2^- \rangle13.80.69t8.22.0
      |\bar D^{*} \Sigma_c; 1/2^- \rangle10.350.01610^{-4}3.4t1.2t0.12t0.23t1.20.25
      |\bar D^{*} \Sigma_c; 3/2^- \rangle10.0050.34t10^{-5}t10^{-5}t\bf1\bf1
      |\bar D \Sigma_c^*; 3/2^- \rangle10.70250t
      |\bar D^* \Sigma_c^*; 1/2^- \rangle1310.300.100.0234t1.5t0.15t0.30t0.35t0.70t4.80.09
      |\bar D^* \Sigma_c^*; 3/2^- \rangle10.0060.0080.39t10^{-5}t10^{-4}t0.04t0.08t0.180.16
      |\bar D^* \Sigma_c^*; 5/2^- \rangle

      Table 3.  Relative branching ratios of the \bar D^{(*)} \Sigma_c^{(*)} hadronic molecular states and their relative production rates in \Lambda_b^0 decays. In the 2rd-12th columns, we show the branching ratios relative to the J/\psi p channel, such as {{\cal{B}}(P_c \to \eta_c p)\over{\cal{B}}(P_c \to J/\psi p)} in the 3rd column. The parameter t \equiv {b_i^2 / a_i^2} ( i=1\cdots7 ) is introduced to measure which processes occur more easily, the process depicted in Fig. 5(a) or the processes depicted in Fig. 5(b, c). In the 13th column, we show the ratio {\cal{R}}_1(P_c) \equiv {{\cal{B}}\left(\Lambda_b^0 \rightarrow P_c K^- \right) \over {\cal{B}}\left(\Lambda_b^0 \rightarrow |\bar D^* \Sigma_c \rangle_{3/2^-} K^- \right)} , and in the 14th column, we show the ratio {\cal{R}}_2(P_c) \equiv { {\cal{B}}(\Lambda_b^0 \to P_c K^- \to J/\psi p K^-) \over {\cal{B}}(\Lambda_b^0 \to |\bar D^* \Sigma_c \rangle_{3/2^-} K^- \to J/\psi p K^-) } . To calculate {\cal{R}}_2 , we a) simply assume t=1 and b) neglect all the spin-3/2 baryons that P_c can decay into, such as the J/\psi N^* and \bar D \Sigma_c^* final states.

    VI.   SUMMARY AND DISCUSSIONS
    • In this paper, we systematically investigate the seven possible \bar D^{(*)} \Sigma_c^{(*)} hadronic molecular states of I=1/2 , including \bar D \Sigma_c of J^P = {1/2}^- , \bar D^* \Sigma_c of J^P = {(1/2)}^-/ {(3/2)}^- , \bar D \Sigma_c^* of J^P = {3/2}^- , and \bar D^* \Sigma_c^* of J^P = {(1/2)}^-/ {(3/2)}^-/ {(5/2)}^-.

      First, we systematically construct their corresponding interpolating currents and calculate their masses and decay constants using QCD sum rules. The results are summarized in Table 1, supporting the interpretations of P_c(4312)^+ , P_c(4440)^+ , and P_c(4457)^+ [5] as the \bar D \Sigma_c and \bar D^* \Sigma_c molecular states. However, the accuracy of our sum rule results is not good enough to distinguish or indentify them. To better understand them, we further study their production and decay properties. The decay constants f_X extracted using QCD sum rules are important input parameters.

      Second, we use current algebra to study the production of \bar D^{(*)} \Sigma_c^{(*)} molecular states in \Lambda_b^0 decays. We derive the relative production rates

      {\cal{R}}_1(P_c) \equiv {{\cal{B}}\left(\Lambda_b^0 \rightarrow P_c K^- \right) \over {\cal{B}}\left(\Lambda_b^0 \rightarrow |\bar D^* \Sigma_c \rangle_{3/2^-} K^- \right)} \, ,

      (127)

      and the obtained results are summarized in Table 3.

      Third, we use the Fierz rearrangement of the Dirac and color indices to study the decay properties of the \bar D^{(*)} \Sigma_c^{*} molecular states, including their decays into charmonium mesons and spin-1/2 light baryons as well as charmed mesons and spin-1/2 charmed baryons, such as J/\psi p and \bar D \Lambda_c . We calculate their relative branching ratios, and the obtained results are also summarized in Table 3. The parameter t \equiv {b_i^2 / a_i^2} ( i=1\cdots7 ) is introduced to measure which processes occur more easily, the process depicted in Fig. 5(a) or the processes depicted in Fig. 5(b, c). Generally, the exchange of one light quark with another light quark may be easier than its exchange with a heavy quark [125]; therefore, it can be the case that t \geq 1 .

      In Table 3, we simply assume t=1 to further calculate the ratio {\cal{R}}_1 in the J/\psi p mass spectrum, that is,

      {\cal{R}}_2(P_c) \equiv { {\cal{B}}(\Lambda_b^0 \to P_c K^- \to J/\psi p K^-) \over {\cal{B}}(\Lambda_b^0 \to |\bar D^* \Sigma_c \rangle_{3/2^-} K^- \to J/\psi p K^-) } \, .

      (128)

      To calculate this ratio, we neglect all spin-3/2 baryons that P_c can decay into, such as the J/\psi N^* and \bar D \Sigma_c^* final states.

      Before drawing conclusions, we would like to note the following:

      ● When studying the masses and decay constants of the \bar D^{(*)} \Sigma_c^{(*)} molecular states using QCD sum rules, we calculate two-point correlation functions at the quark-gluon level as inputs, whereas the masses of charmed mesons and baryons at the hadron level are not used as input parameters. Accordingly, the uncertainty/accuracy is moderate but not sufficient to extract the binding energy. This means that our sum rule results can only suggest but not determine a) whether these \bar D^{(*)} \Sigma_c^{(*)} molecular states exist, and b) whether they are bound or resonance states. Instead, we must assume their existence. We may then use the extracted decay constants to further study their production and decay properties.

      ● When studying the relative production rates of the \bar D^{(*)} \Sigma_c^{(*)} molecular states in \Lambda_b^0 decays using current algebra, we only investigate the hidden-charm pentaquark currents that can couple to these states through an S-wave, that is, J_{1\cdots7} defined in Eqs. (26)–(40). There may be other currents coupling to these states through a P-wave, which are not considered in the present study. Accordingly, |\bar D \Sigma_c^*; 3/2^- \rangle and |\bar D^* \Sigma_c^*; 5/2^- \rangle may still be produced in \Lambda_b^0 decays through these "P-wave" currents. Note that their omission produces theoretical uncertainties.

      ● When studying the decay properties of the \bar D^{(*)} \Sigma_c^{*} molecular states via Fierz rearrangement, we consider the leading-order fall-apart decays described by color-singlet-color-singlet meson-baryon currents but neglect the {\cal{O}}(\alpha_s) corrections described by color-octet-color-octet meson-baryon currents; therefore, there may be other possible decay channels. Moreover, we do not consider the light/charmed baryon fields of J=3/2 ; hence, we cannot study their decays into the J/\psi N^* and \bar D \Sigma_c^* final states. However, we keep all light/charmed baryon fields that couple to the ground-state light/charmed baryons of J^P=1/2^+ ; hence, their decays into these final states are well investigated in this paper.

      Now, we can discuss our uncertainties. The uncertainty on our QCD sum rule results is moderate, whereas the uncertainties on the relative branching ratios as well as the two ratios {\cal{R}}_1 and {\cal{R}}_2 are significantly larger. In the present study, we work under the naïve factorization scheme; therefore, our uncertainties are significantly larger than those of the well-developed QCD factorization scheme [126128], whose uncertainty is at the 5% level when investigating conventional (heavy) hadrons [129]. However, in this paper, we only calculate the ratios, which significantly reduces our uncertainties. Accordingly, we approximately estimate the uncertainty on the relative branching ratios to be at the X^{+100\%}_{-\; 50\%} level. Owing to the omission of the "P-wave" pentaquark currents, the uncertainty on the ratio {\cal{R}}_1 is approximately estimated to be at the X^{+200\%}_{-\; 67\%} level. We further estimate the uncertainty on the ratio {\cal{R}}_2 to be at the X^{+300\%}_{-\; 75\%} level (or even larger due to the assumption that t=1 and the omission of the spin-3/2 baryons that P_c can decay into).

      Finally, we can draw conclusions using the results summarized in Table 3. The LHCb experiment [5] discovered P_c(4312)^+ , P_c(4440)^+ , and P_c(4457)^+ and, at the same time, measured their relative contributions {\cal{R}}\; \equiv \;{\cal{B}}\;(\Lambda^0_b \to P_c^+ K^-)\,{\cal{B}}\,(P_c^+ \to J/\psi p)\,/\,{\cal{B}}\,(\,\Lambda^0_b \to J/\psi p K^-) to be

      \begin{aligned}[b] {\cal{R}}(P_c(4312)^+) =& 0.30 \pm 0.07 ^{+0.34}_{-0.09} \% \, , \\ {\cal{R}}(P_c(4440)^+) =& 1.11 \pm 0.33 ^{+0.22}_{-0.10} \% \, , \\ {\cal{R}}(P_c(4457)^+) =& 0.53 \pm 0.16 ^{+0.15}_{-0.13} \% \, , \end{aligned}

      (129)

      from which we can derive

      \begin{aligned}[b] {{\cal{R}}(P_c(4312)^+) \over {\cal{R}}(P_c(4440)^+)} =& 0.27^{+0.32}_{-0.14} \, , \\ {{\cal{R}}(P_c(4457)^+) \over {\cal{R}}(P_c(4440)^+)} =& 0.48^{+0.25}_{-0.25} \, . \end{aligned}

      (130)

      These two values are approximately consistent with our results,

      \begin{aligned}[b] {\cal{R}}_2(|\bar D \Sigma_c; 1/2^- \rangle) =& {{\cal{R}}_2(|\bar D \Sigma_c; 1/2^- \rangle) \over {\cal{R}}_2(|\bar D^* \Sigma_c; 3/2^- \rangle)} \approx 2.0 \, , \\ {\cal{R}}_2(|\bar D^* \Sigma_c; 1/2^- \rangle) =& {{\cal{R}}_2(|\bar D^* \Sigma_c; 1/2^- \rangle) \over {\cal{R}}_2(|\bar D^* \Sigma_c; 3/2^- \rangle)} \approx 0.25 \, , \end{aligned}

      (131)

      given that their uncertainties are approximately at the X^{+300\%}_{-\; 75\%} level.

      Therefore, our results support the interpretations of P_c(4312)^+ , P_c(4440)^+ , and P_c(4457)^+ as \bar D \Sigma_c of J^P = {1/2}^- , \bar D^* \Sigma_c of J^P = {3/2}^- , and \bar D^* \Sigma_c of J^P = {1/2}^- , respectively. For completeness, we also investigate the interpretations of P_c(4440)^+ and P_c(4457)^+ as the \bar D^* \Sigma_c molecular states of J^P = {1/2}^- and {3/2}^- , respectively, and the results are given in Appendix C.

      Our results suggest that the \bar D^* \Sigma_c^* molecular states of J^P = 1/2^- and 3/2^- may also be observed in the J/\psi p invariant mass spectrum of \Lambda_b^0 \to J/\psi p K^- decays, and their relative contributions are estimated to be

      \begin{aligned}[b] { {\cal{B}}(\Lambda_b^0 \to |\bar D^* \Sigma_c^* \rangle_{1/2^-} K^- \to J/\psi p K^-) \over {\cal{B}}(\Lambda^0_b \to J/\psi p K^-) } \approx 0.1{\text{%}} \, , \end{aligned}

      \begin{aligned}[b] { {\cal{B}}(\Lambda_b^0 \to |\bar D^* \Sigma_c^* \rangle_{3/2^-} K^- \to J/\psi p K^-) \over {\cal{B}}(\Lambda^0_b \to J/\psi p K^-) } \approx 0.2{\text{%}} \, . \end{aligned}

      (132)

      Their relative branching ratios to the \eta_c p , \chi_{c0} p , \chi_{c1} p , h_c p , \bar D^{0} \Lambda_c^+ , \bar D^{*0} \Lambda_c^+ , \bar D^{0} \Sigma_c^+ , D^{-} \Sigma_c^{++} , \bar D^{*0} \Sigma_c^+ , and D^{*-} \Sigma_c^{++} final states are also given for future experimental searches.

    APPENDIX A: SPECTRAL DENSITIES
    • In this appendix, we list the spectral densities \rho_{1\cdots7}(s) extracted for the currents J_{1\cdots7} . In the following expressions, {\cal{F}}(s)=\left[(\alpha+\beta) m_{c}^{2}-\alpha \beta s\right], {\cal{H}}(s)=\left[m_{c}^{2}-\alpha(1-\alpha) s\right], and the integration limits are \alpha_{\rm min}={(1-\sqrt{1-4m_c^2/s})}/{2} , \alpha_{\rm max}={(1+\sqrt{1-4m_c^2/s})}/{2} , \beta_{\rm min}={(\alpha m_c^2)}/{(\alpha s-m_c^2)} , and \beta_{\rm max}=1-\alpha .

      The spectral density \rho_{1}(s) extracted for the current J_{1} is

      \begin{aligned}[b]\\[-6pt] \rho_{1}(s) =& m_c \left( \rho^{\rm pert}_{1a}(s) + \rho^{{\langle\bar qq\rangle}}_{1a}(s) + \rho^{{\langle GG\rangle}}_{1a}(s)+ \rho^{{\langle\bar qGq\rangle}}_{1a}(s) + \rho^{{\langle\bar qq\rangle}^2}_{1a}(s) + \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{1a}(s)+ \rho^{{\langle\bar qGq\rangle}^2}_{1a}(s) + \rho^{{\langle\bar qq\rangle}^3}_{1a}(s) \right) \\ &+ \not q \; \; \left( \rho^{\rm pert}_{1b}(s) + \rho^{{\langle\bar qq\rangle}}_{1b}(s) + \rho^{{\langle GG\rangle}}_{1b}(s)+ \rho^{{\langle\bar qGq\rangle}}_{1b}(s) + \rho^{{\langle\bar qq\rangle}^2}_{1b}(s) + \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{1b}(s)+ \rho^{{\langle\bar qGq\rangle}^2}_{1b}(s) + \rho^{{\langle\bar qq\rangle}^3}_{1b}(s) \right) \, , \end{aligned}\tag{A1}

      where

      \begin{aligned}[b] & \rho^{\rm pert}_{1a}(s) = {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^5 \times \frac{13 (1 - \alpha - \beta)^3}{983040 \pi ^8 \alpha ^5 \beta ^4} \Bigg\} \, , \\ & \rho^{{\langle\bar qq\rangle}}_{1a}(s) = {m_c {\langle\bar qq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^3 \times \frac{-(1 - \alpha - \beta)^2}{768 \pi ^6 \alpha ^3 \beta ^3} \Bigg\} \, , \\& \rho^{{\langle GG\rangle}}_{1a}(s) = {{\langle g_s^2GG\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta}\Bigg\{ m_c^2 {\cal{F}}(s)^2 \times \frac{13 (1 - \alpha - \beta)^3 \left(\alpha ^3+\beta ^3\right)}{1179648 \pi ^8 \alpha ^5 \beta ^4} \\ & \quad\quad\quad\quad + {\cal{F}}(s)^3 \times \frac{(\alpha +\beta -1) \left(80 \alpha ^3+\alpha ^2 (206 \beta -79)+\alpha \left(28 \beta ^2-27 \beta -1\right)-26 (\beta -1)^2 \beta \right)}{2359296 \pi ^8 \alpha ^5 \beta ^3} \Bigg\} \, , \end{aligned}

      \begin{aligned}[b] & \rho^{{\langle\bar qGq\rangle}}_{1a}(s) = {m_c{\langle g_s\bar q\sigma Gq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \times \frac{ (1 - \alpha - \beta) \left(14 \alpha ^2+2 \alpha (15 \beta -7)+(\beta -1) \beta \right)}{8192 \pi ^6 \alpha ^3 \beta ^3} \Bigg\} \, , \\ & \rho^{{\langle\bar qq\rangle}^2}_{1a}(s)= {{\langle\bar qq\rangle}^2 } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \times \frac{-29}{1536 \pi ^4 \alpha ^2 \beta } \Bigg\} \, , \\& \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{1a}(s)= {{\langle\bar qq\rangle}{\langle g_s\bar q\sigma Gq\rangle} } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta \Bigg\{ {\cal{F}}(s) \times \frac{-6 \alpha -29 \beta}{3072 \pi ^4 \alpha ^2 \beta } \Bigg\} + {\cal{H}}(s) \times \frac{55 }{3072 \pi ^4 \alpha } \Bigg\} \, , \end{aligned}

      \begin{aligned}[b] &\rho^{{\langle\bar qGq\rangle}^2}_{1a}(s)= {{\langle g_s\bar q\sigma Gq\rangle}^2 } \Bigg\{\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \frac{52 \alpha ^2-75 \alpha +29}{12288 \pi ^4 \alpha } \Bigg\} + \int^{1}_{0}{\rm d}\alpha \Bigg\{ m_c^2 \delta\left(s - {m_c^2 \over \alpha(1-\alpha)}\right) \times \frac{-13}{6144 \pi ^4 \alpha } \Bigg\}\Bigg\} \, , \\ &\rho^{{\langle\bar qq\rangle}^3}_{1a}(s)= {m_c{\langle\bar qq\rangle}^3 } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \frac{13 }{288 \pi ^2} \Bigg\} \, , \\& \rho^{\rm pert}_{1b}(s) = {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^5 \times \frac{13 (1 - \alpha - \beta)^3}{491520 \pi ^8 \alpha ^4 \beta ^4} \Bigg\} \, , \end{aligned}

      \begin{aligned}[b] &\rho^{{\langle\bar qq\rangle}}_{1b}(s) ={m_c {\langle\bar qq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^3 \times \frac{-29 (1 - \alpha - \beta)^2}{12288 \pi ^6 \alpha ^2 \beta ^3} \Bigg\} \, , \\& \rho^{{\langle GG\rangle}}_{1b}(s) ={{\langle g_s^2GG\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta}\Bigg\{ m_c^2 {\cal{F}}(s)^2 \times \frac{13 (1 - \alpha - \beta)^3 \left(\alpha ^3+\beta ^3\right)}{589824 \pi ^8 \alpha ^4 \beta ^4} \\ &\quad\quad\quad\quad + {\cal{F}}(s)^3 \times \frac{(\alpha +\beta -1) \left(167 \alpha ^2+\alpha (223 \beta -166)+80 \beta ^2-79 \beta -1\right)}{2359296 \pi ^8 \alpha ^3 \beta ^3} \Bigg\} \, , \\ & \rho^{{\langle\bar qGq\rangle}}_{1b}(s) = {m_c{\langle g_s\bar q\sigma Gq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \times \frac{ (1 - \alpha - \beta) \left(110 \alpha ^2+\alpha (217 \beta -110)+3 (\beta -1) \beta \right)}{32768 \pi ^6 \alpha ^2 \beta ^3} \Bigg\} \, , \end{aligned}

      \begin{aligned}[b]& \rho^{{\langle\bar qq\rangle}^2}_{1b}(s)= {{\langle\bar qq\rangle}^2 } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \times \frac{-1}{96 \pi ^4 \alpha \beta } \Bigg\} \, , \\& \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{1b}(s)= {{\langle\bar qq\rangle}{\langle g_s\bar q\sigma Gq\rangle} } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta \Bigg\{ {\cal{F}}(s) \times \frac{-5 \alpha -15 \beta }{3072 \pi ^4 \alpha \beta } \Bigg\} + {\cal{H}}(s) \times \frac{31 }{3072 \pi ^4} \Bigg\} \, , \\& \rho^{{\langle\bar qGq\rangle}^2}_{1b}(s)= {{\langle g_s\bar q\sigma Gq\rangle}^2 } \Bigg\{ \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \frac{30 \alpha ^2-40 \alpha +15}{12288 \pi ^4} \Bigg\} + \int^{1}_{0}{\rm d}\alpha \Bigg\{ m_c^2 \delta\left(s - {m_c^2 \over \alpha(1-\alpha)}\right) \times \frac{-5 }{4096 \pi ^4} \Bigg\} \Bigg\} \, , \\ & \rho^{{\langle\bar qq\rangle}^3}_{1b}(s)= {m_c{\langle\bar qq\rangle}^3 } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \frac{13 \alpha }{576 \pi ^2} \Bigg\} \, . \end{aligned}

      The spectral density \rho_{2}(s) extracted for the current J_{2} is

      \begin{aligned}[b] \rho_{2}(s)=& m_c \left( \rho^{\rm pert}_{2a}(s) + \rho^{{\langle\bar qq\rangle}}_{2a}(s) + \rho^{{\langle GG\rangle}}_{2a}(s)+ \rho^{{\langle\bar qGq\rangle}}_{2a}(s) + \rho^{{\langle\bar qq\rangle}^2}_{2a}(s) + \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{2a}(s)+ \rho^{{\langle\bar qGq\rangle}^2}_{2a}(s) + \rho^{{\langle\bar qq\rangle}^3}_{2a}(s) \right) \\ &+ \not q \; \; \left( \rho^{pert}_{2b}(s) + \rho^{{\langle\bar qq\rangle}}_{2b}(s) + \rho^{{\langle GG\rangle}}_{2b}(s)+ \rho^{{\langle\bar qGq\rangle}}_{2b}(s) + \rho^{{\langle\bar qq\rangle}^2}_{2b}(s) + \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{2b}(s)+ \rho^{{\langle\bar qGq\rangle}^2}_{2b}(s) + \rho^{{\langle\bar qq\rangle}^3}_{2b}(s) \right) \, , \\ \end{aligned}\tag{A2}

      where

      \begin{aligned}[b] &\rho^{\rm pert}_{2a}(s)= {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^5 \times \frac{(1 -\alpha -\beta)^3}{49152 \pi ^8 \alpha ^5 \beta ^4} \Bigg\} \, , \\& \rho^{{\langle\bar qq\rangle}}_{2a}(s) = {m_c {\langle\bar qq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^3 \times \frac{-13 (1 -\alpha -\beta)^2}{3072 \pi ^6 \alpha ^3 \beta ^3} \Bigg\} \, , \\& \rho^{{\langle GG\rangle}}_{2a}(s) = {{\langle g_s^2GG\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta}\Bigg\{ m_c^2 {\cal{F}}(s)^2 \times \frac{5 (1 - \alpha - \beta)^3 \left(\alpha ^3+\beta ^3\right)}{294912 \pi ^8 \alpha ^5 \beta ^4} \\ & \quad\quad\quad\quad + {\cal{F}}(s)^3 \times \frac{(1 - \alpha - \beta) \left(32 \alpha ^3-\alpha ^2 (16 \beta +31)+\alpha \left(-14 \beta ^2+15 \beta -1\right)+10 (\beta -1)^2 \beta \right)}{589824 \pi ^8 \alpha ^5 \beta ^3} \Bigg\} \, ,\\& \rho^{{\langle\bar qGq\rangle}}_{2a}(s) = {m_c{\langle g_s\bar q\sigma Gq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \times \frac{ (1 - \alpha - \beta) (23 \alpha +2 \beta -2)}{4096 \pi ^6 \alpha ^3 \beta ^2} \Bigg\} \, , \\ & \rho^{{\langle\bar qq\rangle}^2}_{2a}(s)= {{\langle\bar qq\rangle}^2 } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \times \frac{-5}{192 \pi ^4 \alpha ^2 \beta } \Bigg\} \, , \\ & \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{2a}(s)= {{\langle\bar qq\rangle}{\langle g_s\bar q\sigma Gq\rangle} } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta \Bigg\{ {\cal{F}}(s) \times \frac{7 \alpha -20 \beta}{1536 \pi ^4 \alpha ^2 \beta } \Bigg\} + {\cal{H}}(s) \times \frac{11 }{512 \pi ^4 \alpha } \Bigg\} \, , \\& \rho^{{\langle\bar qGq\rangle}^2}_{2a}(s)= {{\langle g_s\bar q\sigma Gq\rangle}^2 } \Bigg\{ \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \frac{26 \alpha ^2-53 \alpha +20}{6144 \pi ^4 \alpha } \Bigg\} + \int^{1}_{0}{\rm d}\alpha \Bigg\{ m_c^2 \delta\left(s - {m_c^2 \over \alpha(1-\alpha)}\right) \times \frac{-13}{6144 \pi ^4 \alpha } \Bigg\} \Bigg\} \, , \end{aligned}

      \begin{aligned}[b] \rho^{{\langle\bar qq\rangle}^3}_{2a}(s)= {m_c{\langle\bar qq\rangle}^3 } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \frac{23 }{144 \pi ^2} \Bigg\} \, , \end{aligned}

      \begin{aligned}[b] & \rho^{\rm pert}_{2b}(s) = {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^5 \times \frac{23 (1 -\alpha -\beta)^3}{245760 \pi ^8 \alpha ^4 \beta ^4} \Bigg\} \, , \\& \rho^{{\langle\bar qq\rangle}}_{2b}(s) ={m_c {\langle\bar qq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^3 \times \frac{-5(1 -\alpha -\beta)^2}{1536 \pi ^6 \alpha ^2 \beta ^3} \Bigg\} \, , \\ & \rho^{{\langle GG\rangle}}_{2b}(s) = {{\langle g_s^2GG\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta}\Bigg\{ m_c^2 {\cal{F}}(s)^2 \times \frac{23(1 - \alpha - \beta)^3 \left(\alpha ^3+\beta ^3\right)}{294912 \pi ^8 \alpha ^4 \beta ^4} \\ &\quad\quad\quad\quad + {\cal{F}}(s)^3 \times \frac{(1 - \alpha - \beta) \left(\alpha ^2-\alpha (11 \beta +1)-24 (\beta -1) \beta \right)}{196608 \pi ^8 \alpha ^3 \beta ^3} \Bigg\} \, , \end{aligned}

      \begin{aligned}[b] &\rho^{{\langle\bar qGq\rangle}}_{2b}(s) = {m_c{\langle g_s\bar q\sigma Gq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \times \frac{13 (1 - \alpha - \beta)}{4096 \pi ^6 \alpha \beta ^2} \Bigg\} \, , \\& \rho^{{\langle\bar qq\rangle}^2}_{2b}(s)= {{\langle\bar qq\rangle}^2 } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \times \frac{-13}{384 \pi ^4 \alpha \beta } \Bigg\} \, , \end{aligned}

      \begin{aligned}[b] & \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{2b}(s)= {{\langle\bar qq\rangle}{\langle g_s\bar q\sigma Gq\rangle} } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta \Bigg\{ {\cal{F}}(s) \times \frac{ - 5 \alpha - 24 \beta}{1536 \pi ^4 \alpha \beta } \Bigg\} + {\cal{H}}(s) \times \frac{47 }{1536 \pi ^4} \Bigg\} \, , \\& \rho^{{\langle\bar qGq\rangle}^2}_{2b}(s)= {{\langle g_s\bar q\sigma Gq\rangle}^2 } \Bigg\{ \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \frac{42 \alpha ^2-61 \alpha +24}{6144 \pi ^4} \Bigg\} +\int^{1}_{0}{\rm d}\alpha \Bigg\{ m_c^2 \delta\left(s - {m_c^2 \over \alpha(1-\alpha)}\right) \times \frac{-7}{2048 \pi ^4} \Bigg\} \Bigg\} \, , \\& \rho^{{\langle\bar qq\rangle}^3}_{2b}(s)= {m_c{\langle\bar qq\rangle}^3 } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \frac{5 \alpha }{144 \pi ^2} \Bigg\} \, . \end{aligned}

      The spectral density \rho_{3}(s) extracted for the current J_{3} is

      \begin{aligned}[b] \rho_{3}(s) =& m_c \left( \rho^{\rm pert}_{3a}(s) + \rho^{{\langle\bar qq\rangle}}_{3a}(s) + \rho^{{\langle GG\rangle}}_{3a}(s)+ \rho^{{\langle\bar qGq\rangle}}_{3a}(s) + \rho^{{\langle\bar qq\rangle}^2}_{3a}(s) + \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{3a}(s)+ \rho^{{\langle\bar qGq\rangle}^2}_{3a}(s) + \rho^{{\langle\bar qq\rangle}^3}_{3a}(s) \right) \\ &+ \not q \; \; \left( \rho^{\rm pert}_{3b}(s) + \rho^{{\langle\bar qq\rangle}}_{3b}(s) + \rho^{{\langle GG\rangle}}_{3b}(s)+ \rho^{{\langle\bar qGq\rangle}}_{3b}(s) + \rho^{{\langle\bar qq\rangle}^2}_{3b}(s) + \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{3b}(s)+ \rho^{{\langle\bar qGq\rangle}^2}_{3b}(s) + \rho^{{\langle\bar qq\rangle}^3}_{3b}(s) \right) \, ,\ \end{aligned}\tag{A3}

      where

      \begin{aligned}[b] & \rho^{\rm pert}_{3a}(s) = {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^5 \times \frac{7 (1 - \alpha - \beta)^3 (\alpha +\beta +4)}{3932160 \pi ^8 \alpha ^5 \beta ^4} \Bigg\} \, , \\& \rho^{{\langle\bar qq\rangle}}_{3a}(s) = {m_c {\langle\bar qq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^3 \times \frac{- (1 - \alpha - \beta)^2 (8 \alpha +8 \beta +157)}{147456 \pi ^6 \alpha ^3 \beta ^3} \Bigg\} \, , \\& \rho^{{\langle GG\rangle}}_{3a}(s) = {{\langle g_s^2GG\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta}\Bigg\{ m_c^2 {\cal{F}}(s)^2 \times \frac{7 (1 - \alpha - \beta)^3 (\alpha +\beta +4) \left(\alpha ^3+\beta ^3\right)}{4718592 \pi ^8 \alpha ^5 \beta ^4} \\ &\quad\quad\quad\quad + {\cal{F}}(s)^3 \times \Bigg( \frac{53 \alpha ^5+\alpha ^4 (530 \beta -464)+45 \alpha ^3 \left(22 \beta ^2-16 \beta +17\right)+70 \alpha ^2 \left(8 \beta ^3-3 \beta ^2-5\right)}{28311552 \pi ^8 \alpha ^5 \beta ^3} \\ &\quad\quad\quad\quad+ \frac{\alpha (\beta -1)^2 \left(5 \beta ^2+14 \beta -4\right)-42 (\beta -1)^3 \beta (\beta +4)}{28311552 \pi ^8 \alpha ^5 \beta ^3} \Bigg) \Bigg\} \, , \end{aligned}

      \begin{aligned}[b] & \rho^{{\langle\bar qGq\rangle}}_{3a}(s) = {m_c{\langle g_s\bar q\sigma Gq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \; \frac{(1 - \alpha - \beta) \left(42 \alpha ^2+\alpha (50 \beta +311)+8 \beta ^2+14 \beta -22\right)}{196608 \pi ^6 \alpha ^3 \beta ^2} \Bigg\} \, , \\ &\rho^{{\langle\bar qq\rangle}^2}_{3a}(s)= {{\langle\bar qq\rangle}^2 } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \times \frac{-4 \alpha -4 \beta -1}{384 \pi ^4 \alpha ^2 \beta } \Bigg\} \, , \end{aligned}

      \begin{aligned}[b] & \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{3a}(s)= {{\langle\bar qq\rangle}{\langle g_s\bar q\sigma Gq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s) \times \frac{4 \alpha ^2+\alpha (49-1128 \beta )-96 \beta (4 \beta +1)}{73728 \pi ^4 \alpha ^2 \beta } \Bigg\} \\ &\quad\quad\quad\;\;\quad\quad+ {{\langle\bar qq\rangle}{\langle g_s\bar q\sigma Gq\rangle} } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ {\cal{H}}(s) \times \frac{935 }{73728 \pi ^4 \alpha } \Bigg\} \, , \\& \rho^{{\langle\bar qGq\rangle}^2}_{3a}(s)= {{\langle g_s\bar q\sigma Gq\rangle}^2 } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta \Bigg\{ \frac{\alpha -96 \beta}{73728 \pi ^4 \alpha } \Bigg\} + \frac{546 \alpha ^2-1079 \alpha +480}{294912 \pi ^4 \alpha } \Bigg\} \\ &\quad\quad\quad\;\;\quad+ {{\langle g_s\bar q\sigma Gq\rangle}^2 } \int^{1}_{0}{\rm d}\alpha \Bigg\{ m_c^2 \delta\left(s - {m_c^2 \over \alpha(1-\alpha)}\right) \times \frac{-455 }{294912 \pi ^4 \alpha } \Bigg\} \, , \\& \rho^{{\langle\bar qq\rangle}^3}_{3a}(s)= {m_c{\langle\bar qq\rangle}^3 } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \frac{9}{256 \pi ^2} \Bigg\} \, , \\ & \rho^{\rm pert}_{3b}(s) = {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^5 \times \frac{9 (1 - \alpha - \beta)^3 (\alpha +\beta +2)}{1310720 \pi ^8 \alpha ^4 \beta ^4} \Bigg\} \, , \end{aligned}

      \begin{aligned}[b] & \rho^{{\langle\bar qq\rangle}}_{3b}(s) = {m_c {\langle\bar qq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^3 \times \frac{-5 (1 - \alpha - \beta)^2}{3072 \pi ^6 \alpha ^2 \beta ^3} \Bigg\} \, , \\& \rho^{{\langle GG\rangle}}_{3b}(s) = {{\langle g_s^2GG\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta}\Bigg\{ m_c^2 {\cal{F}}(s)^2 \times \frac{3 (1 - \alpha - \beta)^3 (\alpha +\beta +2) \left(\alpha ^3+\beta ^3\right)}{524288 \pi ^8 \alpha ^4 \beta ^4} + {\cal{F}}(s)^3 \\ &\quad\quad\quad\quad\times \frac{(\alpha +\beta -1) \left(243 \alpha ^3+\alpha ^2 (673 \beta -834)+\alpha \left(761 \beta ^2-743 \beta +588\right)+331 \beta ^3+103 \beta ^2-437 \beta +3\right)}{28311552 \pi ^8 \alpha ^3 \beta ^3} \Bigg\} \, , \\& \rho^{{\langle\bar qGq\rangle}}_{3b}(s) = {m_c{\langle g_s\bar q\sigma Gq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \times \frac{5 (1 - \alpha - \beta) (94 \alpha +3 \beta -3)}{196608 \pi ^6 \alpha ^2 \beta ^2} \Bigg\} \, , \\& \rho^{{\langle\bar qq\rangle}^2}_{3b}(s)= {{\langle\bar qq\rangle}^2 } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \times \frac{-5 (12 \alpha +12 \beta -1)}{6144 \pi ^4 \alpha \beta } \Bigg\} \, , \end{aligned}

      The spectral density \rho_{4}(s) extracted for the current J_{4} is

      \begin{aligned}[b] \rho_{4}(s) =& m_c \left( \rho^{pert}_{4a}(s) + \rho^{{\langle\bar qq\rangle}}_{4a}(s) + \rho^{{\langle GG\rangle}}_{4a}(s)+ \rho^{{\langle\bar qGq\rangle}}_{4a}(s) + \rho^{{\langle\bar qq\rangle}^2}_{4a}(s) + \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{4a}(s)+ \rho^{{\langle\bar qGq\rangle}^2}_{4a}(s) + \rho^{{\langle\bar qq\rangle}^3}_{4a}(s) \right) \\ &+ \not q \; \; \left( \rho^{pert}_{4b}(s) + \rho^{{\langle\bar qq\rangle}}_{4b}(s) + \rho^{{\langle GG\rangle}}_{4b}(s)+ \rho^{{\langle\bar qGq\rangle}}_{4b}(s) + \rho^{{\langle\bar qq\rangle}^2}_{4b}(s) + \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{4b}(s)+ \rho^{{\langle\bar qGq\rangle}^2}_{4b}(s) + \rho^{{\langle\bar qq\rangle}^3}_{4b}(s) \right) \, , \end{aligned}\tag{A4}

      where

      \begin{aligned}[b] & \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{3b}(s)= {{\langle\bar qq\rangle}{\langle g_s\bar q\sigma Gq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s) \times \frac{- 24 \alpha ^2 - \alpha (1088 \beta -61) - 4 \beta (94 \beta -21)}{73728 \pi ^4 \alpha \beta } \Bigg\} \\ &\quad\quad\quad\quad\;\;\quad+ {{\langle\bar qq\rangle}{\langle g_s\bar q\sigma Gq\rangle} } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ {\cal{H}}(s) \times \frac{661 }{73728 \pi ^4} \Bigg\} \, , \end{aligned}

      \begin{aligned}[b] &\rho^{{\langle\bar qGq\rangle}^2}_{3b}(s)= {{\langle g_s\bar q\sigma Gq\rangle}^2 } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta \Bigg\{ \frac{ - 3 \alpha - 47 \beta }{36864 \pi ^4} \Bigg\} + \frac{334 \alpha ^2-663 \alpha +292}{294912 \pi ^4} \Bigg\} \\ &\quad\;\;\quad\quad\quad+ {{\langle g_s\bar q\sigma Gq\rangle}^2 } \int^{1}_{0}{\rm d}\alpha \Bigg\{ m_c^2 \delta\left(s - {m_c^2 \over \alpha(1-\alpha)}\right) \times \frac{-331}{294912 \pi ^4} \Bigg\} \, , \\ &\rho^{{\langle\bar qq\rangle}^3}_{3b}(s)= {m_c{\langle\bar qq\rangle}^3 } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \frac{35 \alpha }{2304 \pi ^2} \Bigg\} \, .\\ & \rho^{\rm pert}_{4a}(s) = {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^5 \times \frac{13 (1 - \alpha - \beta)^3 (\alpha +\beta +4)}{15728640 \pi ^8 \alpha ^5 \beta ^4} \Bigg\} \, , \\& \rho^{{\langle\bar qq\rangle}}_{4a}(s) = {m_c {\langle\bar qq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^3 \times \frac{-(1 - \alpha -\beta)^2 (14 \alpha +14 \beta +43)}{147456 \pi ^6 \alpha ^3 \beta ^3} \Bigg\} \, , \end{aligned}

      \begin{aligned}[b] & \rho^{{\langle GG\rangle}}_{4a}(s) = {{\langle g_s^2GG\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta}\Bigg\{ m_c^2 {\cal{F}}(s)^2 \times \frac{13 (1 - \alpha - \beta)^3 (\alpha +\beta +4) \left(\alpha ^3+\beta ^3\right)}{18874368 \pi ^8 \alpha ^5 \beta ^4} \\ &\quad\quad\quad\quad + {\cal{F}}(s)^3 \times \Bigg\{ \frac{341 \alpha ^5+\alpha ^4 (598 \beta +220)-9 \alpha ^3 \left(10 \beta ^2-130 \beta +163\right)}{113246208 \pi ^8 \alpha ^5 \beta ^3} \\ & \quad\quad\quad\quad + \frac{\alpha ^2 \left(-688 \beta ^3+714 \beta ^2-936 \beta +910\right)-\alpha (\beta -1)^2 \left(419 \beta ^2+1152 \beta +4\right)-78 (\beta -1)^3 \beta (\beta +4)}{113246208 \pi ^8 \alpha ^5 \beta ^3} \Bigg\} \, , \\& \rho^{{\langle\bar qGq\rangle}}_{4a}(s) = {m_c{\langle g_s\bar q\sigma Gq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \\ &\quad\quad\quad\quad \times \frac{(1 - \alpha - \beta) \left(164 \alpha ^3+4 \alpha ^2 (137 \beta +74)+\alpha \left(382 \beta ^2+693 \beta -460\right)-2 \beta \left(\beta ^2+4 \beta -5\right)\right)}{1179648 \pi ^6 \alpha ^3 \beta ^3} \Bigg\} \, , \end{aligned}

      \begin{aligned}[b] & \rho^{{\langle\bar qq\rangle}^2}_{4a}(s)= {{\langle\bar qq\rangle}^2 } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \times \frac{- 4 \alpha - 4 \beta -85 }{24576 \pi ^4 \alpha ^2 \beta } \Bigg\} \, , \\& \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{4a}(s)= {{\langle\bar qq\rangle}{\langle g_s\bar q\sigma Gq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s) \times \frac{- 16 \alpha ^2 - \alpha (40 \beta +46) + \beta (4 \beta +85)}{147456 \pi ^4 \alpha ^2 \beta } \Bigg\} \\ &\quad\quad\;\quad\quad\quad+ {{\langle\bar qq\rangle}{\langle g_s\bar q\sigma Gq\rangle} } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ {\cal{H}}(s) \times \frac{509}{147456 \pi ^4 \alpha } \Bigg\} \, , \\ &\rho^{{\langle\bar qGq\rangle}^2}_{4a}(s)= {{\langle g_s\bar q\sigma Gq\rangle}^2 } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta \Bigg\{ \frac{- 4 \alpha + \beta }{147456 \pi ^4 \alpha } \Bigg\} + \frac{468 \alpha ^2-317 \alpha -89}{589824 \pi ^4 \alpha } \Bigg\} \\&\quad\quad\quad\;\;\quad+ {{\langle g_s\bar q\sigma Gq\rangle}^2 } \int^{1}_{0}{\rm d}\alpha \Bigg\{ m_c^2 \delta\left(s - {m_c^2 \over \alpha(1-\alpha)}\right) \times \frac{-121 }{294912 \pi ^4 \alpha } \Bigg\} \, , \\&\rho^{{\langle\bar qq\rangle}^3}_{4a}(s)= {m_c{\langle\bar qq\rangle}^3 } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \frac{13 }{1536 \pi ^2} \Bigg\} \, , \\& \rho^{\rm pert}_{4b}(s) = {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^5 \times \frac{13 (1 - \alpha - \beta)^3 (\alpha +\beta +2)}{7864320 \pi ^8 \alpha ^4 \beta ^4} \Bigg\} \, , \\& \rho^{{\langle\bar qq\rangle}}_{4b}(s) = {m_c {\langle\bar qq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^3 \times \frac{- (1 - \alpha - \beta)^2 (112 \alpha +112 \beta +155)}{589824 \pi ^6 \alpha ^2 \beta ^3} \Bigg\} \, , \\ & \rho^{{\langle GG\rangle}}_{4b}(s) = {{\langle g_s^2GG\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta}\Bigg\{ m_c^2 {\cal{F}}(s)^2 \times \frac{13 (1 - \alpha - \beta)^3 \left(\alpha ^4+\alpha ^3 (\beta +2)+\alpha \beta ^3+\beta ^3 (\beta +2)\right)}{9437184 \pi ^8 \alpha ^4 \beta ^4} \end{aligned}

      \begin{aligned}[b] & \quad\quad\quad\quad + {\cal{F}}(s)^3 \times \frac{5 (\alpha +\beta -1) \left(136 \alpha ^3+\alpha ^2 (176 \beta +29)+\alpha \left(40 \beta ^2+69 \beta -166\right)-80 \beta ^2+79 \beta +1\right)}{113246208 \pi ^8 \alpha ^3 \beta ^3} \Bigg\} \, , \\& \rho^{{\langle\bar qGq\rangle}}_{4b}(s) = {m_c{\langle g_s\bar q\sigma Gq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \\ &\quad\quad\quad\quad\times \frac{(1 - \alpha - \beta) \left(1312 \alpha ^3+\alpha ^2 (4400 \beta +358)+\alpha \left(3088 \beta ^2+1441 \beta -1670\right)-45 (\beta -1) \beta \right)}{4718592 \pi ^6 \alpha ^2 \beta ^3} \Bigg\} \, , \end{aligned}

      \begin{aligned}[b] &\rho^{{\langle\bar qq\rangle}^2}_{4b}(s)= {{\langle\bar qq\rangle}^2 } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \times \frac{- 2 \alpha - 2 \beta - 17}{6144 \pi ^4 \alpha \beta } \Bigg\} \, , \\& \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{4b}(s)= {{\langle\bar qq\rangle}{\langle g_s\bar q\sigma Gq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s) \times \frac{- 32 \alpha ^2 - \alpha (88 \beta +27) + 75 \beta}{147456 \pi ^4 \alpha \beta } \Bigg\} \\ &\quad\quad\quad\quad\;\;\quad+{{\langle\bar qq\rangle}{\langle g_s\bar q\sigma Gq\rangle} } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ {\cal{H}}(s) \times \frac{437 }{147456 \pi ^4} \Bigg\} \, , \end{aligned}

      \begin{aligned}[b] & \rho^{{\langle\bar qGq\rangle}^2}_{4b}(s)={{\langle g_s\bar q\sigma Gq\rangle}^2 } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta \Bigg\{ \frac{-\alpha }{18432 \pi ^4} \Bigg\} + \frac{386 \alpha ^2-252 \alpha -75}{589824 \pi ^4} \Bigg\} \\ &\quad\;\;\quad\quad\quad+ {{\langle g_s\bar q\sigma Gq\rangle}^2 } \int^{1}_{0}{\rm d}\alpha \Bigg\{ m_c^2 \delta\left(s - {m_c^2 \over \alpha(1-\alpha)}\right) \times \frac{-209 }{589824 \pi ^4}\Bigg\} \, , \\ & \rho^{{\langle\bar qq\rangle}^3}_{4b}(s)= {m_c{\langle\bar qq\rangle}^3 } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \frac{65 \alpha }{9216 \pi ^2} \Bigg\} \, . \end{aligned}

      The spectral density \rho_{5}(s) extracted for the current J_{5} is

      \begin{aligned}[b] \rho_{5}(s) =& m_c \left( \rho^{\rm pert}_{5a}(s) + \rho^{{\langle\bar qq\rangle}}_{5a}(s) + \rho^{{\langle GG\rangle}}_{5a}(s)+ \rho^{{\langle\bar qGq\rangle}}_{5a}(s) + \rho^{{\langle\bar qq\rangle}^2}_{5a}(s) + \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{5a}(s)+ \rho^{{\langle\bar qGq\rangle}^2}_{5a}(s) + \rho^{{\langle\bar qq\rangle}^3}_{5a}(s) \right) \\ &+ \not q \; \; \left( \rho^{\rm pert}_{5b}(s) + \rho^{{\langle\bar qq\rangle}}_{5b}(s) + \rho^{{\langle GG\rangle}}_{5b}(s)+ \rho^{{\langle\bar qGq\rangle}}_{5b}(s) + \rho^{{\langle\bar qq\rangle}^2}_{5b}(s) + \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{5b}(s)+ \rho^{{\langle\bar qGq\rangle}^2}_{5b}(s) + \rho^{{\langle\bar qq\rangle}^3}_{5b}(s) \right) \, , \\ \end{aligned}\tag{A5}

      where

      \begin{aligned}[b] & \rho^{\rm pert}_{5a}(s) ={\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^5 \times \frac{3 (1 - \alpha - \beta)^3}{262144 \pi ^8 \alpha ^5 \beta ^4} \Bigg\} \, , \\& \rho^{{\langle\bar qq\rangle}}_{5a}(s) = {m_c {\langle\bar qq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^3 \times \frac{-11(1-\alpha -\beta)^2}{16384 \pi ^6 \alpha ^3 \beta ^3} \Bigg\} \, , \end{aligned}

      \begin{aligned}[b] & \rho^{{\langle GG\rangle}}_{5a}(s) = {{\langle g_s^2GG\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta}\Bigg\{ m_c^2 {\cal{F}}(s)^2 \times \frac{5 (1 -\alpha -\beta)^3 \left(\alpha ^3+\beta ^3\right)}{524288 \pi ^8 \alpha ^5 \beta ^4} \\ &\quad\quad\quad\quad + {\cal{F}}(s)^3 \times \frac{ (1 - \alpha -\beta) \left(4 \alpha ^3+\alpha ^2 (92 \beta -5)+\alpha \left(94 \beta ^2-95 \beta +1\right)+30 (\beta -1)^2 \beta \right)}{3145728 \pi ^8 \alpha ^5 \beta ^3} \Bigg\} \, , \\& \rho^{{\langle\bar qGq\rangle}}_{5a}(s) = {m_c{\langle g_s\bar q\sigma Gq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \times \frac{45 (1 - \alpha - \beta)}{65536 \pi ^6 \alpha ^2 \beta ^2} \Bigg\} \, , \\& \rho^{{\langle\bar qq\rangle}^2}_{5a}(s)= {{\langle\bar qq\rangle}^2 } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \times \frac{-5}{1024 \pi ^4 \alpha ^2 \beta } \Bigg\} \, , \end{aligned}

      \begin{aligned}[b] & \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{5a}(s)= {{\langle\bar qq\rangle}{\langle g_s\bar q\sigma Gq\rangle} } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta \Bigg\{ {\cal{F}}(s) \times \frac{-\alpha +20 \beta}{24576 \pi ^4 \alpha ^2 \beta } \Bigg\} + {\cal{H}}(s) \times \frac{97 }{24576 \pi ^4 \alpha } \Bigg\} \, , \\ & \rho^{{\langle\bar qGq\rangle}^2}_{5a}(s)={{\langle g_s\bar q\sigma Gq\rangle}^2 } \Bigg\{ \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \frac{74 \alpha ^2-53 \alpha -20}{98304 \pi ^4 \alpha } \Bigg\} + \int^{1}_{0}{\rm d}\alpha \Bigg\{ m_c^2 \delta\left(s - {m_c^2 \over \alpha(1-\alpha)}\right) \times \frac{-37}{98304 \pi ^4 \alpha } \Bigg\}\Bigg\} \, , \\& \rho^{{\langle\bar qq\rangle}^3}_{5a}(s)= {m_c{\langle\bar qq\rangle}^3 } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \frac{7}{256 \pi ^2} \Bigg\} \, , \\& \rho^{\rm pert}_{5b}(s) ={\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^5 \times \frac{21 (1-\alpha -\beta)^3}{1310720 \pi ^8 \alpha ^4 \beta ^4} \Bigg\} \, , \end{aligned}

      \begin{aligned}[b] & \rho^{{\langle\bar qq\rangle}}_{5b}(s) = {m_c {\langle\bar qq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^3 \times \frac{-5(1-\alpha -\beta)^2}{8192 \pi ^6 \alpha ^2 \beta ^3} \Bigg\} \, , \\& \rho^{{\langle GG\rangle}}_{5b}(s) = {{\langle g_s^2GG\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta}\Bigg\{ m_c^2 {\cal{F}}(s)^2 \times \frac{7(1 - \alpha -\beta)^3 \left(\alpha ^3+\beta ^3\right)}{524288 \pi ^8 \alpha ^4 \beta ^4} \\ & \quad\quad\;\;\quad\quad+ {\cal{F}}(s)^3 \times \frac{(\alpha +\beta -1) \left(17 \alpha ^2-\alpha (179 \beta +13)-64 \beta ^2+68 \beta -4\right)}{9437184 \pi ^8 \alpha ^3 \beta ^3} \Bigg\} \, , \end{aligned}

      \begin{aligned}[b] &\rho^{{\langle\bar qGq\rangle}}_{5b}(s) = {m_c{\langle g_s\bar q\sigma Gq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \times \frac{(35 \alpha -2 \beta +2) (1-\alpha -\beta)}{65536 \pi ^6 \alpha ^2 \beta ^2} \Bigg\} \, , \\& \rho^{{\langle\bar qq\rangle}^2}_{5b}(s)= {{\langle\bar qq\rangle}^2 } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \times \frac{-11}{2048 \pi ^4 \alpha \beta } \Bigg\} \, , \\& \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{5b}(s)= {{\langle\bar qq\rangle}{\langle g_s\bar q\sigma Gq\rangle} } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta \Bigg\{ {\cal{F}}(s) \times \frac{-13 \alpha +16 \beta }{24576 \pi ^4 \alpha \beta } \Bigg\} + {\cal{H}}(s) \times \frac{37 }{8192 \pi ^4} \Bigg\} \, , \end{aligned}

      \begin{aligned}[b] & \rho^{{\langle\bar qGq\rangle}^2}_{5b}(s)= {{\langle g_s\bar q\sigma Gq\rangle}^2 } \Bigg\{ \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \frac{90 \alpha ^2-61 \alpha -16}{98304 \pi ^4} \Bigg\} + \int^{1}_{0}{\rm d}\alpha \Bigg\{ m_c^2 \delta\left(s - {m_c^2 \over \alpha(1-\alpha)}\right) \times \frac{-15}{32768 \pi ^4} \Bigg\} \Bigg\} \, , \\& \rho^{{\langle\bar qq\rangle}^3}_{5b}(s)= {m_c{\langle\bar qq\rangle}^3 } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \frac{5 \alpha }{256 \pi ^2} \Bigg\} \, . \end{aligned}

      The spectral density \rho_{6}(s) extracted for the current J_{6} is

      \begin{aligned}[b] \rho_{6}(s) =& m_c \left( \rho^{\rm pert}_{6a}(s) + \rho^{{\langle\bar qq\rangle}}_{6a}(s) + \rho^{{\langle GG\rangle}}_{6a}(s)+ \rho^{{\langle\bar qGq\rangle}}_{6a}(s) + \rho^{{\langle\bar qq\rangle}^2}_{6a}(s) + \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{6a}(s)+ \rho^{{\langle\bar qGq\rangle}^2}_{6a}(s) + \rho^{{\langle\bar qq\rangle}^3}_{6a}(s) \right) \\ &+\not q \; \; \left( \rho^{\rm pert}_{6b}(s) + \rho^{{\langle\bar qq\rangle}}_{6b}(s) + \rho^{{\langle GG\rangle}}_{6b}(s)+ \rho^{{\langle\bar qGq\rangle}}_{6b}(s) + \rho^{{\langle\bar qq\rangle}^2}_{6b}(s) + \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{6b}(s)+ \rho^{{\langle\bar qGq\rangle}^2}_{6b}(s) + \rho^{{\langle\bar qq\rangle}^3}_{6b}(s) \right) \, , \end{aligned}\tag{A6}

      where

      \begin{aligned}[b]& \rho^{\rm pert}_{6a}(s) = {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^5 \times \frac{7 (1 - \alpha - \beta)^3 (\alpha +\beta +4)}{15728640 \pi ^8 \alpha ^5 \beta ^4} \Bigg\} \, , \\& \rho^{{\langle\bar qq\rangle}}_{6a}(s) = {m_c {\langle\bar qq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^3 \times \frac{-5(1 - \alpha - \beta)^2 (8 \alpha +8 \beta +31)}{196608 \pi ^6 \alpha ^3 \beta ^3} \Bigg\} \, , \\& \rho^{{\langle GG\rangle}}_{6a}(s) = {{\langle g_s^2GG\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta}\Bigg\{ m_c^2 {\cal{F}}(s)^2 \times \frac{7(1 - \alpha - \beta)^3 (\alpha +\beta +4) \left(\alpha ^3+\beta ^3\right)}{18874368 \pi ^8 \alpha ^5 \beta ^4} \end{aligned}

      \begin{aligned}[b] &\quad\quad\quad\quad+ {\cal{F}}(s)^3 \times \Bigg\{ \frac{-391 \alpha^5 - 2 \alpha ^4 (839 \beta +326) - 3 \alpha ^3 \left(766 \beta ^2-96 \beta -819\right) - 42 (\beta -1)^3 \beta (\beta +4)}{113246208 \pi ^8 \alpha ^5 \beta ^3} \\ &\quad\quad\quad\quad+ \frac{-2 \alpha ^2 \left(584 \beta ^3-417 \beta ^2-864 \beta +697\right) - \alpha (\beta -1)^2 \left(199 \beta ^2+546 \beta +20\right)}{113246208 \pi ^8 \alpha ^5 \beta ^3} \Bigg\} \Bigg\} \, , \\& \rho^{{\langle\bar qGq\rangle}}_{6a}(s) = {m_c{\langle g_s\bar q\sigma Gq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \times \frac{(1 - \alpha - \beta) (110 \alpha +110 \beta +243)}{262144 \pi ^6 \alpha ^2 \beta ^2} \Bigg\} \, , \\& \rho^{{\langle\bar qq\rangle}^2}_{6a}(s)= {{\langle\bar qq\rangle}^2 } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \times \frac{4 \alpha +4 \beta -11}{2048 \pi ^4 \alpha ^2 \beta } \Bigg\} \, , \end{aligned}

      \begin{aligned}[b] &\rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{6a}(s)= {{\langle\bar qq\rangle}{\langle g_s\bar q\sigma Gq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s) \times \frac{28 \alpha ^2+\alpha (168 \beta +67)+8 \beta (11-4 \beta )}{98304 \pi ^4 \alpha ^2 \beta } \Bigg\} \\ &\quad\quad\quad\;\;\quad\quad+ {{\langle\bar qq\rangle}{\langle g_s\bar q\sigma Gq\rangle} } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ {\cal{H}}(s) \times \frac{301 }{98304 \pi ^4 \alpha } \Bigg\} \, , \\& \rho^{{\langle\bar qGq\rangle}^2}_{6a}(s)= {{\langle g_s\bar q\sigma Gq\rangle}^2 } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta \Bigg\{ \frac{7 \alpha -8 \beta}{98304 \pi ^4 \alpha } \Bigg\} + \frac{342 \alpha ^2-381 \alpha -56}{393216 \pi ^4 \alpha } \Bigg\} \\&\quad\;\;\quad\quad\quad+ {{\langle g_s\bar q\sigma Gq\rangle}^2 } \int^{1}_{0}{\rm d}\alpha \Bigg\{ m_c^2 \delta\left(s - {m_c^2 \over \alpha(1-\alpha)}\right) \times \frac{-133}{393216 \pi ^4 \alpha } \Bigg\} \, , \end{aligned}

      \begin{aligned}[b] & \rho^{{\langle\bar qq\rangle}^3}_{6a}(s)= {m_c{\langle\bar qq\rangle}^3 } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \frac{25 }{1024 \pi ^2} \Bigg\} \, , \\& \rho^{\rm pert}_{6b}(s) = {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^5 \times \frac{5(1 - \alpha - \beta)^3 (\alpha +\beta +2)}{1048576 \pi ^8 \alpha ^4 \beta ^4} \Bigg\} \, , \\& \rho^{{\langle\bar qq\rangle}}_{6b}(s) = {m_c {\langle\bar qq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^3 \times \frac{-(1 - \alpha - \beta)^2 (16 \alpha +16 \beta +5)}{49152 \pi ^6 \alpha ^2 \beta ^3} \Bigg\} \, , \\& \rho^{{\langle GG\rangle}}_{6b}(s) = {{\langle g_s^2GG\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta}\Bigg\{ m_c^2 {\cal{F}}(s)^2 \times \frac{25 (1 - \alpha - \beta)^3 \left(\alpha ^4+\alpha ^3 (\beta +2)+\alpha \beta ^3+\beta ^3 (\beta +2)\right)}{6291456 \pi ^8 \alpha ^4 \beta ^4} \\ &\quad\quad\quad\quad + {\cal{F}}(s)^3 \times \Bigg\{ \frac{(1 - \alpha - \beta) \left(261 \alpha ^3+\alpha ^2 (1799 \beta -738)+\alpha \left(1615 \beta ^2-1117 \beta +516\right)\right)}{113246208 \pi ^8 \alpha ^3 \beta ^3} \\ & \quad\quad\quad\quad + \frac{(1 - \alpha - \beta) \left(77 \beta ^3+761 \beta ^2-799 \beta -39\right)}{113246208 \pi ^8 \alpha ^3 \beta ^3} \Bigg\} \Bigg\} \, , \end{aligned}

      \begin{aligned}[b] &\rho^{{\langle\bar qGq\rangle}}_{6b}(s) = {m_c{\langle g_s\bar q\sigma Gq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \; \frac{ (1 - \alpha - \beta) \left(472 \alpha ^2+\alpha (488 \beta -68)+16 \beta ^2-11 \beta -5\right)}{786432 \pi ^6 \alpha ^2 \beta ^2} \Bigg\} , \\& \rho^{{\langle\bar qq\rangle}^2}_{6b}(s)= {{\langle\bar qq\rangle}^2 } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \times \frac{-20 \alpha -20 \beta -45}{8192 \pi ^4 \alpha \beta } \Bigg\} \, , \\& \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{6b}(s)= {{\langle\bar qq\rangle}{\langle g_s\bar q\sigma Gq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s) \times \frac{- 24 \alpha ^2 - \alpha (224 \beta +9) + 12 \beta (2 \beta +7)}{98304 \pi ^4 \alpha \beta } \Bigg\} \\ &\quad\quad\;\;\quad\quad\quad+ {{\langle\bar qq\rangle}{\langle g_s\bar q\sigma Gq\rangle} } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ {\cal{H}}(s) \times \frac{743 }{98304 \pi ^4} \Bigg\} \, , \\ & \rho^{{\langle\bar qGq\rangle}^2}_{6b}(s)={{\langle g_s\bar q\sigma Gq\rangle}^2 } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta \Bigg\{ \frac{ (\beta -\alpha )}{16384 \pi ^4} \Bigg\} + \frac{602 \alpha ^2-461 \alpha -108}{393216 \pi ^4} \Bigg\} \end{aligned}

      \begin{aligned}[b] &\quad\quad\quad\quad+ {{\langle g_s\bar q\sigma Gq\rangle}^2 } \int^{1}_{0}{\rm d}\alpha \Bigg\{ m_c^2 \delta\left(s - {m_c^2 \over \alpha(1-\alpha)}\right) \times \frac{-353}{393216 \pi ^4} \Bigg\} \, , \\ &\rho^{{\langle\bar qq\rangle}^3}_{6b}(s)= {m_c{\langle\bar qq\rangle}^3 } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \frac{35 \alpha }{9216 \pi ^2} \Bigg\} \, . \end{aligned}

      The spectral density \rho_{7}(s) extracted for the current J_{7} is

      \begin{aligned}[b] \rho_{7}(s) =& m_c \left( \rho^{\rm pert}_{7a}(s) + \rho^{{\langle\bar qq\rangle}}_{7a}(s) + \rho^{{\langle GG\rangle}}_{7a}(s)+ \rho^{{\langle\bar qGq\rangle}}_{7a}(s) + \rho^{{\langle\bar qq\rangle}^2}_{7a}(s) + \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{7a}(s)+ \rho^{{\langle\bar qGq\rangle}^2}_{7a}(s) + \rho^{{\langle\bar qq\rangle}^3}_{7a}(s) \right) \\ &+ \not q \; \; \left( \rho^{\rm pert}_{7b}(s) + \rho^{{\langle\bar qq\rangle}}_{7b}(s) + \rho^{{\langle GG\rangle}}_{7b}(s)+ \rho^{{\langle\bar qGq\rangle}}_{7b}(s) + \rho^{{\langle\bar qq\rangle}^2}_{7b}(s) + \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{7b}(s)+ \rho^{{\langle\bar qGq\rangle}^2}_{7b}(s) + \rho^{{\langle\bar qq\rangle}^3}_{7b}(s) \right) \, , \end{aligned}\tag{A7}

      where

      \begin{aligned}[b] \rho^{\rm pert}_{7a}(s) =& {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^5 \times \frac{7 (1 - \alpha - \beta)^3 \left(3 \alpha ^2+2 \alpha (3 \beta +7)+3 \beta ^2+14 \beta +33\right)}{88473600 \pi ^8 \alpha ^5 \beta ^4} \Bigg\} \, , \\ \rho^{{\langle\bar qq\rangle}}_{7a}(s) =& {m_c {\langle\bar qq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^3 \times \frac{-(1 - \alpha - \beta)^2 (10 \alpha +10 \beta +23)}{73728 \pi ^6 \alpha ^3 \beta ^3} \Bigg\} \, , \end{aligned}

      \begin{aligned}[b] \rho^{{\langle GG\rangle}}_{7a}(s) =& {{\langle g_s^2GG\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta}\Bigg\{m_c^2 {\cal{F}}(s)^2 \times \Bigg\{ \frac{7(1 - \alpha - \beta)^3 \left(3 \alpha ^5+2 \alpha ^4 (3 \beta +7)+\alpha ^3 \left(3 \beta ^2+14 \beta +33\right)+3 \alpha ^2 \beta ^3\right)}{106168320 \pi ^8 \alpha ^5 \beta ^4} \\ & + \frac{7(1 - \alpha - \beta)^3 \left(2 \alpha \beta ^3 (3 \beta +7)+\beta ^3 \left(3 \beta ^2+14 \beta +33\right)\right)}{106168320 \pi ^8 \alpha ^5 \beta ^4} \Bigg\} \\ &+ {\cal{F}}(s)^3 \times \Bigg\{ \frac{(\alpha +\beta -1) \left(252 \alpha ^5-\alpha ^4 (324 \beta +1273)-\alpha ^3 \left(2136 \beta ^2+3771 \beta +3733\right)\right)}{1274019840 \pi ^8 \alpha ^5 \beta ^3} \\ & + \frac{(\alpha +\beta -1) \left(\alpha ^2 \left(2544 \beta ^3+5595 \beta ^2+818 \beta -4817\right)-84 (\beta -1)^2 \beta \left(3 \beta ^2+14 \beta +33\right)\right)}{1274019840 \pi ^8 \alpha ^5 \beta ^3} \\ & + \frac{(\alpha +\beta -1) \left(-\alpha \left(1236 \beta ^4+3769 \beta ^3+1717 \beta ^2-6785 \beta +63\right)\right)}{1274019840 \pi ^8 \alpha ^5 \beta ^3} \Bigg\} \Bigg\} \, , \end{aligned}

      \begin{aligned}[b] \rho^{{\langle\bar qGq\rangle}}_{7a}(s) =& {m_c{\langle g_s\bar q\sigma Gq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \times \frac{-530 \alpha ^3 - 105 \alpha ^2 (10 \beta +1) - 102 \alpha \left(5 \beta ^2+\beta -6\right) + (\beta -1)^2 (10 \beta +23)}{1769472 \pi ^6 \alpha ^3 \beta ^2} \Bigg\} \, , \\ \rho^{{\langle\bar qq\rangle}^2}_{7a}(s)=& {{\langle\bar qq\rangle}^2 } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \times \frac{- 10 \alpha - 10 \beta - 1}{3072 \pi ^4 \alpha ^2 \beta } \Bigg\} \, , \end{aligned}

      \begin{aligned}[b] & \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{7a}(s)= {{\langle\bar qq\rangle}{\langle g_s\bar q\sigma Gq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s) \times \frac{ 10 \alpha ^2-140 \alpha \beta +\alpha +3 \beta (10 \beta +1) }{55296 \pi ^4 \alpha ^2 \beta } \Bigg\} \\ &\quad\;\quad\quad\quad\quad+{{\langle\bar qq\rangle}{\langle g_s\bar q\sigma Gq\rangle} } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ {\cal{H}}(s) \times \frac{11 }{3072 \pi ^4 \alpha } \Bigg\} \, , \\& \rho^{{\langle\bar qGq\rangle}^2}_{7a}(s)={{\langle g_s\bar q\sigma Gq\rangle}^2 } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta \Bigg\{ \frac{5 \alpha + 15 \beta}{110592 \pi ^4 \alpha } \Bigg\} + \frac{108 \alpha ^2-86 \alpha -33}{221184 \pi ^4 \alpha } \Bigg\} \\ &\quad\quad\;\;\quad\quad+ {{\langle g_s\bar q\sigma Gq\rangle}^2 } \int^{1}_{0}{\rm d}\alpha \Bigg\{ m_c^2 \delta\left(s - {m_c^2 \over \alpha(1-\alpha)}\right) \times \frac{-11}{24576 \pi ^4 \alpha } \Bigg\} \, , \end{aligned}

      \begin{aligned}[b] & \rho^{{\langle\bar qq\rangle}^3}_{7a}(s)= {m_c{\langle\bar qq\rangle}^3 } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \frac{7 }{864 \pi ^2} \Bigg\} \, , \\ & \rho^{\rm pert}_{7b}(s) = {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^5 \times \frac{7 (1 - \alpha - \beta)^3 \left(6 \alpha ^2+\alpha (12 \beta +13)+6 \beta ^2+13 \beta +21\right)}{58982400 \pi ^8 \alpha ^4 \beta ^4} \Bigg\} \, , \\ &\rho^{{\langle\bar qq\rangle}}_{7b}(s) = {m_c {\langle\bar qq\rangle} } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^3 \times \frac{- (1 - \alpha - \beta)^2 (13 \alpha +13 \beta +20)}{73728 \pi ^6 \alpha ^2 \beta ^3} \Bigg\} \, , \\& \rho^{{\langle\bar qq\rangle}^2}_{7b}(s)= {{\langle\bar qq\rangle}^2 } {\int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha\int^{\beta_{\rm max}}_{\beta_{\rm min}}{\rm d}\beta} \Bigg\{ {\cal{F}}(s)^2 \times \frac{- 13 \alpha - 13 \beta + 2}{3072 \pi ^4 \alpha \beta } \Bigg\} \, , \\& \rho^{{\langle\bar qq\rangle}^3}_{7b}(s)= {m_c{\langle\bar qq\rangle}^3 } \int^{\alpha_{\rm max}}_{\alpha_{\rm min}}{\rm d}\alpha \Bigg\{ \frac{35 \alpha}{5184 \pi ^2} \Bigg\} \, . \end{aligned}

      However, \rho^{{\langle GG\rangle}}_{7b}(s) , \rho^{{\langle\bar qGq\rangle}}_{7b}(s) , \rho^{{\langle\bar qq\rangle}{\langle\bar qGq\rangle}}_{7b}(s) , and \rho^{{\langle\bar qGq\rangle}^2}_{7b}(s) are too complicated for extraction.

    APPENDIX B: UNCERTAINTIES DUE TO PHASE ANGLES
    • There are two different terms, A \equiv [\bar c_a \gamma_\mu c_a]N and B \equiv [\bar c_a \sigma_{\mu\nu} c_a]N , both of which can contribute to the decay of |\bar D \Sigma_c^{*}; 3/2^- \rangle into J/\psi p . Their relevant effective Lagrangians are

      {\cal{L}}^A_{\psi p} = g_A\; \bar P_c^\alpha \left( t_1 g_{\alpha\mu} + t_2 \sigma_{\alpha\mu} \right) N\; \psi^\mu \, , \tag{B1}

      {\cal{L}}^B_{\psi p} = g_B\; \bar P_c^\alpha \left( t_3 g_{\alpha\mu}\gamma_\nu + t_4 \epsilon_{\alpha\mu\nu\rho} \gamma^\rho \gamma_5 \right) N\; \partial^\mu\psi^\nu \, , \tag{B2}

      where t_i are free parameters. The two terms A and B can also contribute to the decays of |\bar D^{*} \Sigma_c; 1/2^- \rangle and |\bar D^{*} \Sigma_c^{*}; 1/2^- \rangle into J/\psi p . Now, the two effective Lagrangians are

      {\cal{L}}^C_{\psi p} = g_C\; \bar P_c \gamma_\mu \gamma_5 N\; \psi^\mu \, ,\tag{B3}

      {\cal{L}}^D_{\psi p}= g_D\; \bar P_c \sigma_{\mu\nu} \gamma_5 N\; \partial^\mu\psi^\nu \, . \tag{B4}

      There are two different terms, C \equiv [\bar c_a \gamma_5 c_a]N and D \equiv [\bar c_a \gamma_\mu \gamma_5 c_a]N , both of which can contribute to the decays of |\bar D \Sigma_c; 1/2^- \rangle , |\bar D^{*} \Sigma_c; 1/2^- \rangle , and |\bar D^{*} \Sigma_c^{*}; 1/2^- \rangle into \eta_c p . Their relevant effective Lagrangians are

      {\cal{L}}^E_{\eta_c p}=g_E\; \bar P_c N\; \eta_c \, , \tag{B5}

      {\cal{L}}^F_{\eta_c p} = g_F\; \bar P_c \gamma_\mu N\; \partial^\mu\eta_c \, . \tag{B6}

      There may be phase angles between g_A/g_B , g_C/g_D , and g_E/g_F , none of which can be well determined in the present study. In this appendix, we rotate these phase angles and redo all calculations. Their relevant (theoretical) uncertainties are summarized in Table B1.

      ConfigurationDecay channelsProductions
      J/\psi p\eta_c p\chi_{c0} p\chi_{c1} ph_c p\bar D^{0} \Lambda_c^+\bar D^{*0} \Lambda_c^+\bar D^{0} \Sigma_c^+D^{-} \Sigma_c^{++}\bar D^{*0} \Sigma_c^+D^{*-} \Sigma_c^{++}{\cal{R}}_1{\cal{R}}_2
      |\bar D \Sigma_c; 1/2^- \rangle10.53.80.69t8.22.0-5.0
      |\bar D^{*} \Sigma_c; 1/2^- \rangle0.91.60.33.10.01610^{-4}3.4t1.2t0.12t0.23t1.20.20.4
      |\bar D^{*} \Sigma_c; 3/2^- \rangle10.0050.34t10^{-5}t10^{-5}t\bf1\bf1
      |\bar D \Sigma_c^*; 3/2^- \rangle17100.70250t
      |\bar D^* \Sigma_c^*; 1/2^- \rangle1253310.300.100.0234t1.5t0.15t0.30t0.35t0.70t4.80.12.4
      |\bar D^* \Sigma_c^*; 3/2^- \rangle10.0060.0080.39t10^{-5}t10^{-4}t0.04t0.08t0.180.16
      |\bar D^* \Sigma_c^*; 5/2^- \rangle

      Table B1.  Relative branching ratios of the \bar D^{(*)} \Sigma_c^{(*)} hadronic molecular states and their relative production rates in \Lambda_b^0 decays. See the caption of Table 3 for detailed explanations. In this table, we consider the (theoretical) uncertainties due to the phase angles between g_A/g_B , g_C/g_D , and g_E/g_F .

    APPENDIX C: INVERSE INTERPRETATIONS
    • In this paper, we intend to interpret P_c(4440)^+ and P_c(4457)^+ as the \bar D^* \Sigma_c molecular states of J^P = 3/2^- and 1/2^- , respectively. However, they can also be interpreted as the \bar D^* \Sigma_c molecular states of J^P = 1/2^- and 3/2^- , respectively. Based on the latter interpretations, we assume the masses of the \bar D^{(*)} \Sigma_c^{(*)} molecular states to be

      \begin{aligned}[b] M_{|\bar D \Sigma_c; 1/2^- \rangle} =& M_{P_c(4312)^+} = 4311.9\; {\rm{MeV}} \, , \\ M_{|\bar D^{*} \Sigma_c; 1/2^- \rangle} =& M_{P_c(4440)^+} = 4440.3\; {\rm{MeV}} \, , \\ M_{|\bar D^{*} \Sigma_c; 3/2^- \rangle} =& M_{P_c(4457)^+} = 4457.3\; {\rm{MeV}} \, , \end{aligned}

      \begin{aligned}[b] M_{|\bar D \Sigma_c^{*}; 3/2^- \rangle} \approx& M_{D} + M_{\Sigma_c^*} = 4385\; {\rm{MeV}} \, , \\ M_{|\bar D^{*} \Sigma_c^*; 1/2^- \rangle} \approx& M_{D^*} + M_{\Sigma_c^*} = 4527\; {\rm{MeV}} \, , \\ M_{|\bar D^{*} \Sigma_c^*; 3/2^- \rangle} \approx& M_{D^*} + M_{\Sigma_c^*} = 4527\; {\rm{MeV}} \, , \\ M_{|\bar D^{*} \Sigma_c^*; 5/2^- \rangle} \approx& M_{D^*} + M_{\Sigma_c^*} = 4527\; {\rm{MeV}} \, , \end{aligned}\tag{C1}

      and redo all calculations. We summarize the obtained results in Table C1. Even when considering the uncertainty on {\cal{R}}_2 to be at the X^{+300\%}_{-\; 75\%} level, these results do not appear to easily explain the relative contributions {\cal{R}} \equiv {\cal{B}}(\Lambda^0_b \to P_c^+ K^-){\cal{B}}(P_c^+ \to J/\psi p)/{\cal{B}}(\Lambda^0_b \to J/\psi p K^-) measured by the LHCb experiment [5], as given in Eqs. (129).

      ConfigurationDecay channelsProductions
      J/\psi p\eta_c p\chi_{c0} p\chi_{c1} ph_c p\bar D^{0} \Lambda_c^+\bar D^{*0} \Lambda_c^+\bar D^{0} \Sigma_c^+D^{-} \Sigma_c^{++}\bar D^{*0} \Sigma_c^+D^{*-} \Sigma_c^{++}{\cal{R}}_1{\cal{R}}_2
      |\bar D \Sigma_c; 1/2^- \rangle13.80.69t8.62.1
      |\bar D^{*} \Sigma_c; 1/2^- \rangle10.360.0133.4t1.2t0.11t0.22t1.30.28
      |\bar D^{*} \Sigma_c; 3/2^- \rangle10.00510^{-4}0.35t10^{-5}t10^{-5}t\bf1\bf1
      |\bar D \Sigma_c^*; 3/2^- \rangle10.70250t
      |\bar D^* \Sigma_c^*; 1/2^- \rangle1310.300.100.0234t1.5t0.15t0.30t0.35t0.70t5.00.10
      |\bar D^* \Sigma_c^*; 3/2^- \rangle10.0060.0080.39t10^{-5}t10^{-4}t0.04t0.08t0.190.17
      |\bar D^* \Sigma_c^*; 5/2^- \rangle

      Table C1.  Relative branching ratios of the \bar D^{(*)} \Sigma_c^{(*)} hadronic molecular states and their relative production rates in \Lambda_b^0 decays. See the caption of Table 3 for detailed explanations. In this table, we work under the assumption that P_c(4440)^+ and P_c(4457)^+ are interpreted as the \bar D^* \Sigma_c molecular states of J^P = 1/2^- and 3/2^- , respectively.

Reference (129)

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