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2023, 47(1): 1-2.
Abstract:
2023, 47(1): 011001. doi: 10.1088/1674-1137/ac9b2b
Abstract:
Considering that the negative pressure of the accelerated expansion of the universe results from the cosmological constant or the dark energy quintessence, we use the dark energy quintessence to construct the "quintessential" phase space. In contrast to the previous discussion in which the cosmological constant is considered as the black hole (BH) phase transition pressure, in this analysis, we believe that the pressure results from quintessence. The characteristics of critical behavior, Gibbs free energy, and temperature behavior in quintessential phase space are investigated. We observe that the phase transition belongs to van der Waals phase transition within\begin{document}$-1 <\omega_{\rm q}<-2/3$\end{document}. If \begin{document}$\omega_{\rm q}$\end{document}is within (–2/3, –1/3), the phase transition loses the large BH phase transition characteristics, which is caused by the later stage of the phase transition being completely dominated by quintessence dark energy with negative pressure. These results suggest that the quintessential phase space can be constructed with the pressure from the thermal quintessence, and it can be used as a new probe to explore the thermodynamics of BHs.
2023, 47(1): 013001. doi: 10.1088/1674-1137/ac957c
Abstract:
Two photon collisions offer a variety of physics phenomena that can be studied at future electron-positron colliders. Using the planned CEPC parameters as a benchmark, we consider several topics within two-photon collisions. With the full integrated luminosity, Higgs boson photoproduction can be reliably observed, and large statistics on various quarkonium states can be collected. The LEP results for the photon structure function and tau lepton anomalous magnetic moment can be improved by 1-2 orders of magnitude.
2023, 47(1): 013002. doi: 10.1088/1674-1137/ac9895
Abstract:
Using \begin{document}$(448.1 \pm 2.9) \times 10^{6}$\end{document} \begin{document}$\psi(3686)$\end{document} events collected with the BESIII detector, we perform the first search for the weak baryonic decay \begin{document}$\psi(3686) \to \Lambda_c^{+} \bar{\Sigma}^- +c.c.$\end{document}. The analysis procedure is optimized using a blinded method. No significant signal is observed, and the upper limit on the branching fraction (\begin{document}$\mathcal B$\end{document}) of \begin{document}$\psi(3686) \to \Lambda_c^{+} \bar{\Sigma}^- +c.c.$\end{document} is set as \begin{document}$1.4\times 10^{-5}$\end{document} at the 90% confidence level.
2023, 47(1): 013101. doi: 10.1088/1674-1137/ac936b
Abstract:
We study the deep inelastic scattering (DIS) of a proton-targeted lepton in the presence of gluon condensation using gauge/gravity duality. We use a modified \begin{document}${\rm AdS}_5$\end{document} background where the modification parameter c corresponds to the gluon condensation in the boundary theory. First, by examining the electromagnetic field, we establish that a non-zero c can increase field magnitude. Our aim is to obtain the acceptable value of c for this scattering. Our method is based on setting the mass of the proton as an eigenvalue of the baryonic state equations of the DIS to find the acceptable value of the parameter c on the other side of the equations. Therefore, in the second step, we calculate wave function equations for the baryonic states where the mass of the proton target requires a value contribution of c as \begin{document}$c=0.0120 \; \rm GeV^4$\end{document}. Proceeding with the electromagnetic field and baryonic states, we derive the holographic interaction action related to the amplitude of the scattering. Finally, we compute the corresponding structure functions numerically as functions of x and q, which are Björken variables and the lepton momentum transfers, respectively. Comparing the Jlab Hall C data with our theoretical calculations, our results are acceptable.
2023, 47(1): 013102. doi: 10.1088/1674-1137/ac93ed
Abstract:
In this study, we systematically investigated two-pseudoscalar meson systems with the Bethe-Salpeter equation in the ladder and instantaneous approximations. By solving the Bethe-Salpeter equation numerically with the kernel containing the one-particle exchange diagrams, we found that the \begin{document}$K\bar{K}$\end{document}, \begin{document}$DK$\end{document}, \begin{document}$B\bar{K}$\end{document}, \begin{document}$D\bar{D}$\end{document}, \begin{document}$B\bar{B}$\end{document}, \begin{document}$BD$\end{document}, \begin{document}$D\bar{K}$\end{document}, \begin{document}$BK$\end{document}, and \begin{document}$B\bar{D}$\end{document} systems with \begin{document}$I=0$\end{document} can exist as bound states. We also studied the contributions from heavy meson (\begin{document}$J/\psi$\end{document} and \begin{document}$\Upsilon$\end{document}) exchanges and found that the contributions from heavy meson exchanges cannot be ignored.
2023, 47(1): 013103. doi: 10.1088/1674-1137/ac945a
Abstract:
We study the \begin{document}$B_{c,u,d}\to X(3872)P$\end{document} decays in the perturbative QCD (PQCD) approach, involving the puzzling resonance \begin{document}$X(3872)$\end{document}, where P represents a light pseudoscalar meson (K or π). Assuming \begin{document}$X(3872)$\end{document} to be a \begin{document}$1^{++}$\end{document} charmonium state, we obtain the following results. (a) The branching ratios of the \begin{document}$B^+_c\to X(3872)\pi^+$\end{document} and \begin{document}$B^+_c\to X(3872) K^+$\end{document} decays are consistent with the results predicted by the covariant light-front approach within errors; however, they are larger than those given by the generalized factorization approach. (b) The branching ratio of the \begin{document}$B^+\to X(3872)K^+$\end{document} decay is predicted as \begin{document}$(3.8^{+1.1}_{-1.0})\times10^{-4}$\end{document}, which is smaller than the previous PQCD calculation result but still slightly larger than the upper limits set by Belle and BaBar. Hence, we suggest that the\begin{document}$B^{0,+}\to X(3872)K^{0,+}$\end{document} decays should be precisely measured by the LHCb and Belle II experiments to help probe the inner structure of \begin{document}$X(3872)$\end{document}. (c) Compared with the \begin{document}$B_{u,d}\to X(3872)K$\end{document}decays, the \begin{document}$B_{u,d}\to X(3872)\pi$\end{document} decays have significantly smaller branching ratios, which drop to values as low as \begin{document}$10^{-6}$\end{document}. (d) The direct CP violations of these considered decays are small (\begin{document}$10^{-3}\sim 10^{-2}$\end{document}) because the penguin contributions are loop suppressed compared to the tree contributions. The mixing-induced CP violation of the \begin{document}$B\to X(3872)K^0_S$\end{document} decay is highly consistent with the current world average value \begin{document}$\sin2\beta=(69.9\pm1.7)$\end{document}%. Experimentally testing the results for the branching ratios and CP violations, including the implicit \begin{document}$S U(3)$\end{document} and isospin symmetries of these decays, helps probe the nature of \begin{document}$X(3872)$\end{document}.
2023, 47(1): 013104. doi: 10.1088/1674-1137/ac957a
Abstract:
We study the electromagnetic form factors and tensor polarization observables of the deuteron in the framework of the hard-wall AdS/QCD model. We find a profile function for the bulk twist \begin{document}$\tau=6$\end{document} vector field, which describes the deuteron on the boundary and fix the infrared boundary cut-off of AdS space in accordance with the ground state mass of the deuteron. We obtain the deuteron charge monopole, quadrupole, and magnetic dipole form factors and tensor polarization observables from the bulk Lagrangians for the deuteron and photon field interactions. We plot the momentum transfer dependence of the form factors and tensor polarization observables and compare our numerical results with those in the soft-wall model and experimental data.
2023, 47(1): 013105. doi: 10.1088/1674-1137/ac9889
Abstract:
Inspired by the LHCb observations of hidden-charm \begin{document}$P_{c(s)}$\end{document} states, we study their hidden-strange analog\begin{document}$P_s$\end{document} states in both the \begin{document}$[udu][\bar ss]$\end{document} and \begin{document}$[uds][\bar su]$\end{document} configurations. We investigate \begin{document}$P_s$\end{document} pentaquark states in the \begin{document}$p\eta^\prime$\end{document}, \begin{document}$p\phi$\end{document}, \begin{document}$\Lambda K$\end{document}, \begin{document}$\Sigma K$\end{document}, and \begin{document}$\Sigma^\ast K^\ast$\end{document} structures with \begin{document}$J^P ={1}/{2}^-$\end{document} and \begin{document}$\Sigma ^\ast K$\end{document} and \begin{document}$\Sigma K^\ast$\end{document} with \begin{document}$J^P = {3}/{2}^-$\end{document} and calculate their masses in the framework of QCD sum rules. Our numerical results show that the extracted hadron masses for all the \begin{document}$p\eta^\prime$\end{document}, \begin{document}$p\phi$\end{document}, \begin{document}$\Lambda K$\end{document}, \begin{document}$\Sigma K$\end{document}, and \begin{document}$\Sigma^\ast K^\ast$\end{document} structures are significantly higher than the \begin{document}$\Sigma K$\end{document} mass threshold, and the masses for \begin{document}$\Sigma ^\ast K$\end{document} and \begin{document}$\Sigma K^\ast$\end{document}are also higher than the threshold of the corresponding hadron; hence, no bound state exists in such channels, which is consistent with the current experimental status.
2023, 47(1): 013106. doi: 10.1088/1674-1137/ac9894
Abstract:
Using gauge/gravity duality, we study the potential energy and the melting of triply heavy baryon at finite temperature and chemical potential in this paper. First, we calculate the three-quark potential and compare the results with quark-antiquark potential. With the increase of temperature and chemical potential, the potential energy will decrease at large distances. It is found that the three-quark potential will have an endpoint at high temperature and/or large chemical potential, which means triply heavy baryons will melt at enough high temperature and/or large chemical potential. We also discuss screening distance which can be extracted from the three-quark potential. At last, we draw the melting diagram of triply heavy baryons in the \begin{document}$T-\mu$\end{document} plane.
2023, 47(1): 013107. doi: 10.1088/1674-1137/ac9896
Abstract:
Motivated by recent supersymmetry (SUSY) search results, which prefer most SUSY particles to be heavy, and the muon g–2 anomaly, which prefers colorless SUSY particles to be light, we explore the status of a light smuon (the SUSY partner of a left-handed muon lepton) in the next-to-minimal supersymmetric standard model (NMSSM). Assuming colored SUSY particles to be heavy, and considering numerous experimental constraints, including muon g-2, SUSY searches, and dark matter, we scan the parameter space in the NMSSM with \begin{document}$\mathbb{Z}_3$\end{document}-symmetry and check the status of colorless SUSY particles and their possible mass order, paying special attention to the smuon. After calculations and discussions, we find that the surviving samples can be divided into several scenarios, where the mass region and decay information of the smuon are given. Overall, the smuon mass can be approximately 0.1~1.8 TeV. These results may be useful for smuon searches at the LHC and future colliders.
2023, 47(1): 013108. doi: 10.1088/1674-1137/ac9897
Abstract:
A new Goldstone particle named Majoron is introduced in order to explain the origin of neutrino mass via some new physics models assuming that neutrinos are Majorana particles. By expanding the signal region and using likelihood analysis, it becomes possible to search for Majoron using experiments originally designed to search for \begin{document}$\mu-e$\end{document} conversion. For the COMET experiment, the sensitivity of process \begin{document}$\mu \rightarrow eJ$\end{document} is able to reach \begin{document}${\cal{B}}(\mu \rightarrow eJ)=2.3\times 10^{-5}$\end{document} in Phase-I and \begin{document}$O(10^{-8})$\end{document} in Phase-II. Meanwhile, the sensitivities to search for Majoron in future experiments are also discussed in this article.
2023, 47(1): 013109. doi: 10.1088/1674-1137/ac9aab
Abstract:
In this study, we tentatively identify \begin{document}$P_{cs}(4338)$\end{document} as the \begin{document}$\bar{D}\Xi_c$\end{document}molecular state and distinguish the isospins of current operators to explore in detail the\begin{document}$\bar{D}\Xi_c$\end{document}, \begin{document}$\bar{D}\Lambda_c$\end{document}, \begin{document}$\bar{D}_s\Xi_c$\end{document}, \begin{document}$\bar{D}_s\Lambda_c$\end{document}, \begin{document}$\bar{D}^*\Xi_c$\end{document}, \begin{document}$\bar{D}^*\Lambda_c$\end{document}, \begin{document}$\bar{D}^*_s\Xi_c$\end{document}, and \begin{document}$\bar{D}^*_s\Lambda_c$\end{document} molecular states without strange, with strange, and with double strange in the framework of QCD sum rules. The present exploration favors identifying \begin{document}$P_{cs}(4338)$\end{document} (\begin{document}$P_{cs}(4459)$\end{document}) as the \begin{document}$\bar{D}\Xi_c$\end{document} (\begin{document}$\bar{D}^*\Xi_c$\end{document}) molecular state with the spin-parity \begin{document}$J^P={\dfrac{1}{2}}^-$\end{document} (\begin{document}${\dfrac{3}{2}}^-$\end{document}) and isospin \begin{document}$(I,I_3)=(0,0)$\end{document}, and the observation of their cousins with the isospin \begin{document}$(I,I_3)=(1,0)$\end{document} in the \begin{document}$J/\psi\Sigma^0/\eta_c\Sigma^0$\end{document} invariant mass distributions would decipher their inner structures.
2023, 47(1): 013110. doi: 10.1088/1674-1137/aca00d
Abstract:
The ground vector \begin{document}$B_{c}^{\ast}$\end{document} meson has not yet been experimentally discovered until now. Besides the dominant electromagnetic decays, nonleptonic weak decays provide another choice to search for the mysterious \begin{document}$B_{c}^{\ast}$\end{document} mesons. Inspired by the potential prospects of \begin{document}$B_{c}^{\ast}$\end{document} mesons in future high-luminosity colliders, nonleptonic \begin{document}$B_{c}^{\ast}$\end{document} weak decays induced by bottom and charm quark decays are studied within the SM by using a naive factorization approach. It is found that for \begin{document}$B_{c}^{\ast}$\end{document} \begin{document}${\to}$\end{document} \begin{document}$B_{s,d}{\pi}$\end{document}, \begin{document}$B_{s,d}^{\ast}{\pi}$\end{document}, \begin{document}$B_{s,d}{\rho}$\end{document}, \begin{document}$B_{s}K$\end{document}, \begin{document}$B_{s}^{\ast}K$\end{document}, \begin{document}$B_{s}K^{\ast}$\end{document}, \begin{document}${\eta}_{c}(1S,2S){\pi}$\end{document}, \begin{document}${\eta}_{c}(1S,2S){\rho}$\end{document} and \begin{document}${\psi}(1S,2S){\pi}$\end{document} decays, a few hundred and even thousands of events might be observable in CEPC, FCC-ee and LHCb@HL-LHC experiments.
2023, 47(1): 013111. doi: 10.1088/1674-1137/ac9deb
Abstract:
To date, the behavior of the pionic leading-twist distribution amplitude (DA) \begin{document}$\phi_{2;\pi}(x,\mu)$\end{document} \begin{document}$-$\end{document}which is a universal physical quantity and is introduced into high-energy processes involving pions based on the factorization theorem\begin{document}$-$\end{document} is not completely consistent. The form of \begin{document}$\phi_{2;\pi}(x,\mu)$\end{document} is usually described by phenomenological models and constrained by the experimental data on exclusive processes containing pions or the moments computed using QCD sum rules and the lattice QCD theory. Evidently, an appropriate model is extremely important to determine the exact behavior of \begin{document}$\phi_{2;\pi}(x,\mu)$\end{document}. In this paper, by adopting the least squares method to fit the ξ-moments calculated using QCD sum rules based on the background field theory, we perform an analysis on several commonly used models of the pionic leading-twist DA in the literature; these include the truncation form of the Gegenbauer polynomial series, the light-cone harmonic oscillator model, the form extracted from the Dyson-Schwinger equations, the model from the light-front holographic AdS/QCD, and a simple power-law parametrization form.
2023, 47(1): 014001. doi: 10.1088/1674-1137/ac9e9a
Abstract:
A transfer reaction and cluster-decay experiment, \begin{document}$^{12}$\end{document}C(\begin{document}$^{16}$\end{document}O,\begin{document}$^{24}$\end{document}Mg\begin{document}$\rightarrow$\end{document}α+\begin{document}$^{20}$\end{document}Ne)α, was performed at a beam energy of 96 MeV. Both recoil and decay α particles were detected in coincidence, allowing us to deduce the energy-momentum of a \begin{document}$^{20}$\end{document}Ne fragment. A number of resonant states of \begin{document}$^{24}$\end{document}Mg were reconstructed up to an excitation energy of approximately 30 MeV. Owing to the experimentally achieved excellent resolutions of the Q-value and excitation-energy spectra, the relative decay widths for each resonant state in\begin{document}$^{24}$\end{document}Mg to various final states of \begin{document}$^{20}$\end{document}Ne were extracted, along with the total decay width. The obtained results provide good testing ground for theoretical descriptions of multiple clustering configurations in\begin{document}$^{24}$\end{document}Mg.
2023, 47(1): 014101. doi: 10.1088/1674-1137/ac94bd
Abstract:
In the present work, based on the Wentzel-Kramers-Brillouin (WKB) theory, considering the cluster preformation probability (\begin{document}$P_{c}$\end{document}), we systematically investigate the cluster radioactivity half-lives of 22 trans-lead nuclei ranging from 221Fr to 242Cm. When the mass number of the emitted cluster \begin{document}$A_{c}$\end{document} \begin{document}$<$\end{document} 28, \begin{document}$P_{c}$\end{document} is obtained by the exponential relationship of \begin{document}$P_{c}$\end{document} to the α decay preformation probability (\begin{document}$P_{\alpha}$\end{document}) proposed by R. Blendowskeis \begin{document}$et$\end{document} \begin{document}$al.$\end{document} [Phys. Rev. Lett. 61, 1930 (1988)], while \begin{document}$P_{\alpha}$\end{document} is calculated through the cluster-formation model (CFM). When \begin{document}$A_{c}$\end{document} \begin{document}$\ge$\end{document} 28, \begin{document}$P_{c}$\end{document} is calculated through the charge-number dependence of \begin{document}$P_{c}$\end{document} on the decay products proposed by Ren \begin{document}$et$\end{document} \begin{document}$al.$\end{document} [Phys. Rev. C 70, 034304 (2004)]. The half-lives of cluster radioactivity have been calculated by the density-dependent cluster model [Phys. Rev. C 70, 034304 (2004)] and by the unified formula of half-lives for alpha decay and cluster radioactivity [Phys. Rev. C 78, 044310 (2008)]. For comparison, a universal decay law (UDL) proposed by Qi \begin{document}$et$\end{document} \begin{document}$al.$\end{document} [Phys. Rev. C 80, 044326 (2009)], a semi-empirical model for both α decay and cluster radioactivity proposed by Santhosh [J. Phys. G: Nucl. Part. Phys. 35, 085102 (2008)], and a unified formula of half-lives for alpha decay and cluster radioactivity [Phys. Rev. C 78, 044310 (2008)] are also used. The calculated results of our work, Ni's formula , and the UDL can well reproduce the experimental data and are better than those of Santhosh's model. In addition, we extend this model to predict the half-lives for 51 nuclei, whose cluster radioactivity is energetically allowed or observed but not yet quantified in NUBASE2020.
2023, 47(1): 014102. doi: 10.1088/1674-1137/ac9601
Abstract:
Many isotopes of Np, Pu, Am, and Cm around the N = 126 shell still have not been produced in the laboratory. This study aims to investigate the cross sections and yields of the neutron-deficient nuclei of Np, Pu, Am, and Cm produced in the proton-induced spallations of transuranium elements. The isospin-dependent quantum molecular dynamics (IQMD) model is applied to study the dynamical process of reaction, and the subsequent decay process is simulated by the GEMINI++ model. The IQMD-GEMINI++ model is applied to calculate the cross section, kinetic energy, and angular distribution of the isotopic productions around N = 126. The Lindhand, Scharff, and Schiott theory is applied to calculate the energy loss of different heavy nuclei in the target material. A comparison between the data and the calculations shows that the IQMD-GEMINI++ model can reproduce the production cross sections of the neutron-deficient nuclei in spallation within approximately 1.5 orders of magnitude. The maximum cross section of the undiscovered isotopes of Np, Pu, Am, and Cm is about 10−5 mb, while the kinetic energies of the productions are all less than 16 MeV. The angular distribution shows that the emission direction of production is mostly at a backward angle. The range of production in the target is within the range of 10−7 to 10−5 cm. This range is the effective target thickness for the online identification of undiscovered isotopes. Based on the effective thickness of the target and assuming an intensity of 120 μA for the proton beam, the yields of the undiscovered neutron-deficient nuclei are calculated. Productions of the undiscovered isotopes of Np, Pu, Am, and Cm by the proton-induced spallations of transuranium elements are feasible. However, experimental techniques for online identification of neutron-deficient nuclei produced in proton-induced spallation should be developed.
2023, 47(1): 014103. doi: 10.1088/1674-1137/ac9888
Abstract:
Within the Bayesian framework, using an explicitly isospin-dependent parametric equation of state (EOS) for the core of neutron stars (NSs), we studied how the NS EOS behaves when we confront it with the tidal deformabilities \begin{document}$\Lambda_{1.4}$\end{document} of canonical NSs with different error and different lower boundaries, and with the tidal deformabilities of massive NSs. We found that it does not significantly improve the constraints on the NS EOS but has a weak effect on narrowing down the slope parameter of the symmetry energy by decreasing the measurement errors of \begin{document}$\Lambda_{1.4}$\end{document}. Both the isospin-dependent and isospin-independent parts of the NS EOS were significantly constrained and raised as the tidal deformabilities of massive NSs were adopted in the calculations, especially in high-density regions. We also found that \begin{document}$\Lambda_{1.4}$\end{document} is more competent to limit the curvature parameter than the slope parameter of the symmetry energy, whereas the opposite occurs for the radius of canonical NSs \begin{document}$R_{1.4}$\end{document}. The tidal deformability of an NS with two times the solar mass \begin{document}$\Lambda_{2.0}$\end{document} is more sensitive to skewness than the curvature parameter of the symmetry energy, and \begin{document}$\Lambda_{1.4}$\end{document} and \begin{document}$R_{1.4}$\end{document} have no correlation with the former.
2023, 47(1): 014104. doi: 10.1088/1674-1137/ac9de8
Abstract:
Despite its success with mass spectra, the reputation of the bag model has been marred by embarrassment of the center of mass motion. It leads to severe theoretical inconsistencies. For instance, the masses and the decay constants would no longer be independent of the momentum. In this work, we provide a systematic approach to resolving this problem. Our framework can consistently compute the meson decay constants and baryon transition form factors. Notably, the form factors in the neutron β decays do not depend on any free parameters and are determined to be\begin{document}$F^V_1 =1$\end{document} and \begin{document}$F^A_1 = 1.31$\end{document} or \begin{document}$F_1^A/F_1^V= 1.31$\end{document}, which is close to the experimental value of \begin{document}$F^A_1/F^V_1 = 1.27$\end{document}. In addition, we find that \begin{document}${\cal B} (\Lambda_b \to \Lambda \gamma) = (6.8 \pm 3.3 ) \times 10^{-6}$\end{document}, which agrees to the experimental value of \begin{document}$(7.1\pm 1.7)\times 10^{-6}$\end{document}.
2023, 47(1): 014105. doi: 10.1088/1674-1137/ac9893
Abstract:
In addition to the Coulomb displacement energy, the residual differences between the binding energies of mirror nuclei (a pair of nuclei with the same mass number plus interchanged proton and neutron numbers) contribute to the shell effect via the valence scheme in this study. To this end, one linear combining type of valence nucleon number, namely, \begin{document}$\alpha N_p+\beta N_n$\end{document}, is chosen to tackle this shell correction, in which \begin{document}$N_p$\end{document} and \begin{document}$N_n$\end{document} are the valence proton and neutron numbers with respect to the nearest shell closure, respectively. The mass differences of mirror nuclei, as the sum of the empirical Coulomb displacement energy and shell effect correction, are then used to obtain the binding energies of proton-rich nuclei through the available data of their mirror partners to explore the proton dripline of the nuclear chart.
2023, 47(1): 014106. doi: 10.1088/1674-1137/ac9a36
Abstract:
In this study, we systematically investigate the ϕ meson and nucleus interaction by analyzing and fitting the cross sections of \begin{document}$\gamma N$\end{document}\begin{document}$\rightarrow \phi$\end{document}N reactions near the threshold, where N represents the nucleus. Using the vector meson dominant model, the distribution of the ϕ-N scattering length is presented as a function of energy, and the results show that there is a slight increase in scattering length with increasing energy. Based on this, the average scattering length of a ϕ-proton is obtained as\begin{document}$0.10\pm0.01$\end{document} fm by combining experimental data and theoretical models. Moreover, the average scattering length of the ϕ-deuteron interaction is derived to be \begin{document}$0.014\pm0.002$\end{document} fm for the first time. Furthermore, the effect of the momentum transfer \begin{document}$|t_{{\rm min}}|$\end{document} on the ϕ-N scattering length at the threshold is discussed. The obtained results not only provide important theoretical information for a more comprehensive and accurate study of the ϕ-N scattering length, but also a basis for future experimental measurements of ϕ meson production.
2023, 47(1): 015001. doi: 10.1088/1674-1137/ac9371
Abstract:
The Large High Altitude Air Shower Observatory (LHAASO) has three sub-arrays, KM2A, WCDA, and WFCTA. The flux variations of cosmic ray air showers were studied by analyzing the KM2A data during a thunderstorm on June 10, 2021. The number of shower events that meet the trigger conditions increases significantly in atmospheric electric fields, with a maximum fractional increase of 20%. The variations in trigger rates (increases or decreases) were found to be strongly dependent on the primary zenith angle. The flux of secondary particles increased significantly, following a trend similar to that of shower events. To better understand the observed behavior, Monte Carlo simulations were performed with CORSIKA and G4KM2A (a code based on GEANT4). We found that the experimental data (in saturated negative fields) were in good agreement with the simulations, assuming the presence of a uniform electric field of -700 V/cm with a thickness of 1500 m in the atmosphere above the observation level. Due to the acceleration/deceleration by the atmospheric electric field, the number of secondary particles with energy above the detector threshold was modified, resulting in the changes in shower detection rate.
2023, 47(1): 015101. doi: 10.1088/1674-1137/ac945b
Abstract:
The cosmic distance duality relation (DDR) is constrained by a combination of type-Ia supernovae (SNe Ia) and strong gravitational lensing (SGL) systems using the deep learning method. To make use of the full SGL data, we reconstruct the luminosity distance from SNe Ia up to the highest redshift of SGL using deep learning, and then, this luminosity distance is compared with the angular diameter distance obtained from SGL. Considering the influence of the lens mass profile, we constrain the possible violation of the DDR in three lens mass models. The results show that, in the singular isothermal sphere and extended power-law models, the DDR is violated at a high confidence level, with the violation parameter \begin{document}$\eta_0=-0.193^{+0.021}_{-0.019}$\end{document} and \begin{document}$\eta_0=-0.247^{+0.014}_{-0.013}$\end{document}, respectively. In the power-law model, however, the DDR is verified within a 1σ confidence level, with the violation parameter \begin{document}$\eta_0=-0.014^{+0.053}_{-0.045}$\end{document}. Our results demonstrate that the constraints on the DDR strongly depend on the lens mass models. Given a specific lens mass model, the DDR can be constrained at a precision of \begin{document}$O(10^{-2})$\end{document} using deep learning.
2023, 47(1): 015102. doi: 10.1088/1674-1137/ac94bc
Abstract:
We studied the surface geometry and shadows of a Schwarzschild black hole with a halo containing quadrupolar and octopolar terms. It was found that the quadrupole term causes a Schwarzschild black hole to be prolate at the quadrupole strength \begin{document}${\cal{Q}}<0$\end{document} and oblate at \begin{document}${\cal{Q}}>0$\end{document}, and the octopole term causes to the shadow stretch upward at the octopolar strength ngth \begin{document}${\cal{O}}<0$\end{document} and downward at \begin{document}${\cal{O}}>0$\end{document}. The shadow of a Schwarzschild black hole with a halo stretches and squeezes along the horizontal direction at \begin{document}${\cal{Q}}<0$\end{document} and \begin{document}${\cal{Q}}>0$\end{document}, respectively. Meanwhile, the black hole shadow shifts upward at \begin{document}${\cal{O}}<0$\end{document} and downward at \begin{document}${\cal{O}}>0$\end{document}. We present the light rays that form the shadow boundary to explain the emergence of the extraordinary patterns of the black hole shadow with quadrupole and octopole terms. From the observable width W, height H, oblateness K, and distortion parameter \begin{document}$\delta_{c}$\end{document} of the black hole shadow, we can determine the quadrupole and octopolar strengths of a Schwarzschild black hole with a halo. Our results show that the quadrupolar and octopolar terms yield a series of interesting patterns for the shadow of a Schwarzschild black hole with a halo.
2023, 47(1): 015103. doi: 10.1088/1674-1137/ac957b
Abstract:
We search for a possible relationship between weak gravity conjecture (WGC) and conformal field theory (CFT) in hyperscaling violating and Kerr-Newman-AdS black holes. We deal with the critical points of the black hole systems using the correlation function introduced in CFT and discuss WGC conditions using the imaginary part of the energy obtained from the critical points and their poles. Under the assumptions \begin{document}$z=1$\end{document}, \begin{document}$d=1$\end{document}, and \begin{document}$\theta\rightarrow0^{-}$\end{document}, we link WGC to hyperscaling violating black holes owing to the existence of \begin{document}$r_{H}$\end{document} values larger and smaller than one. For the second black hole system, we study the conditions of WGC for Kerr-Newman-AdS black holes using rotation and radius parameters. Then, we show that the conditions of WGC are satisfied when the charged particle near the hyperscaling violating and Kerr-Newman black holes is \begin{document}$\frac{1}{a}$\end{document} with a ratio \begin{document}$\frac{a}{\ell}\ll 1$\end{document}.
2023, 47(1): 015104. doi: 10.1088/1674-1137/ac9603
Abstract:
In the present study, we investigate the anisotropic stellar solutions admitting Finch-Skea symmetry (viable and non-singular metric potentials) in the presence of some exotic matter fields, such as Bose-Einstein Condensate (BEC) dark matter, the Kalb-Ramond fully anisotropic rank-2 tensor field from the low-energy string theory effective action, and the gauge field imposing \begin{document}$U(1)$\end{document} symmetry. Interior spacetime is matched with both Schwarzchild and Reissner-Nördstrom vacuum spacetimes for BEC, KB, and gauge fields. In addition, we study the energy conditions, Equation of State (EoS), radial derivatives of energy density and anisotropic pressures, Tolman-Oppenheimer-Volkoff equilibrium condition, relativistic adiabatic index, sound speed, and surface redshift. Most of the aforementioned conditions are satisfied. Therefore, the solutions derived in the current study lie in the physically acceptable regime.
2023, 47(1): 015105. doi: 10.1088/1674-1137/ac9d28
Abstract:
In light of our previous study [Chin. Phys. C 44(8), 085103 (2020)], we investigate the possibility of the formation of a primordial black hole in the second inflationary process induced by the oscillation of the curvaton. By adopting the instability of the Mathieu equation, one can utilize the δ function to fully describe the power spectrum. Owing to the running of the curvaton mass, we can simulate the value of the abundance of primordial black holes covering almost all of the mass ranges. Three special cases are given. One case may account for dark matter because the abundance of a primordial black hole is approximately 75% . As late times, the relic of exponential potential may be approximated to a constant of the order of a cosmological constant, which is dubbed as the role of dark energy. Thus, our model could unify dark energy and dark matter from the perspective of phenomenology. Finally, it sheds new light on exploring Higgs physics.
2023, 47(1): 015106. doi: 10.1088/1674-1137/ac9b2c
Abstract:
In this study, the gravitational decoupling approach via extended geometric deformation is utilized to generate analytical black hole solutions owing to its simplicity and effectiveness. Considering the external fields surrounding Schwarzschild AdS black holes, we derive hairy black hole solutions in asymptotic AdS spacetime, satisfying the strong and dominant energy conditions. Moreover, we find that if the black hole spacetime is a fluid system, the fluid under each of these conditions is anisotropic.
2023, 47(1): 015107. doi: 10.1088/1674-1137/ac9aaa
Abstract:
In this article, a new class of solutions of Einstein-Maxwell field equations of relativistic strange quark stars obtained in dimensions \begin{document}$D\geq4$\end{document}, is shown. We assume that the geometry of space-time is pseudo-spheroid, embedded in Euclidean space of \begin{document}$(D-1)$\end{document} dimensions. The MIT bag model equation of state \begin{document}$(henceforth~EoS)$\end{document} is employed to study the relevant properties of strange quark stars. For the causal and non-negative nature of the square of the radial sound velocity \begin{document}$({v_{r}}^{2})$\end{document}, we observe that some restrictions exist on the reduced radius \begin{document}$(\frac{b}{R})$\end{document}, where R is a parameter related to the curvature of the space-time, and b is the radius of the star. The spheroidal parameter λ used here defines the metric potential of the \begin{document}$g_{rr}$\end{document} component, which is pseudo-spheroidal in nature. We note that the pressure anisotropy and charge have some effects on λ. The maximum mass for a given surface density (\begin{document}$\rho_s$\end{document}) or bag constant \begin{document}$(B)$\end{document} assumes a maximum value in dimension \begin{document}$D=5$\end{document}and decreases for other values of D. The generalized Buchdahl limit for a higher dimensional charged star is also obeyed in this model. We observe that in this model, we can predict the mass of a strange quark star using a suitable value of the electric charge (Q) and bag constant (B). Energy and stability conditions are also satisfied in this model. Stability is also studied considering the dependence of the Lagrangian perturbation of radial pressure (\begin{document}$\Delta p_r$\end{document}) on the frequency of normal modes of oscillations. The tidal Love number and tidal de-formability are also evaluated.
2023, 47(1): 015108. doi: 10.1088/1674-1137/ac9fb9
Abstract:
In this study, we investigate the influence of the angular momentum of a charged particle around Kerr-Newman-Taub-NUT black holes on the Lyapunov exponent and find spatial regions where the chaos bound is violated. The exponent is obtained by solving the determination of the eigenvalues of a Jacobian matrix in the phase space. Equilibrium positions are obtained by fixing the charge-to-mass ratio of the particle and changing its angular momentum. For certain values of the black holes' electric charge, the NUT charge and rotational parameter, a small angular momentum of the particle, even with zero angular momentum, causes violation of the bound. This violation disappears at a certain distance from the event horizon of the non-extremal Kerr-Newman-Taub-NUT black hole when the angular momentum increases to a certain value. When the black hole is extremal, the violation always exists no matter how the angular momentum changes. The ranges of the angular momentum and spatial regions for the violation are found. The black holes and particle rotating in the same and opposite directions are discussed.