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PARTICLES AND FIELDS
Localization of five-dimensional Elko spinors on dS/AdS thick branes
Xiang-Nan Zhou, Yun-Zhi Du, Xin-Yuan Ma, Zhen-Hua Zhao
2022, 46(2): 023101. doi: 10.1088/1674-1137/ac3122
Abstract:
Owing to the special structure of a five-dimensional Elko spinor, its localization on a brane with codimension one becomes completely different from that of a Dirac spinor. By introducing the coupling between the Elko spinor and the scalar field that can generate the brane, we have two types of localization mechanism for the five-dimensional Elko spinor zero mode on a brane. One is the Yukawa-type coupling, and the other is the non-minimal coupling. In this study, we investigate the localization of the Elko zero mode on de Sitter and Anti-de Sitter thick branes with the two localization mechanisms, respectively. The results show that both the mechanisms can achieve localization. The forms of the scalar coupling function in both localization mechanisms have similar properties, and they play a similar role in localization.
Kotzinian-Mulders effect in semi-inclusive DIS within TMD factorization
Xuan Luo, Hao Sun
2022, 46(2): 023102. doi: 10.1088/1674-1137/ac3124
Abstract:
In this study, we investigate the Kotzinian-Mulders effect under semi-inclusive deep inelastic scattering (SIDIS) within the framework of transverse momentum dependent (TMD) factorization. The asymmetry is contributed by the convolution of the Kotzinian-Mulders function \begin{document}$ g_{1T}$\end{document} and the unpolarized fragmentation function \begin{document}$ D_1$\end{document}. As a TMD distribution, the Kotzinian-Mulders function in the coordinate space in the perturbative region can be represented as the convolution of the C-coefficients and the corresponding collinear correlation function. The Wandzura-Wilczek approximation is used to obtain this correlation function. We perform a detailed phenomenological numerical analysis of the Kotzinian-Mulders effect in the SIDIS process within TMD factorization at the kinematics of the HERMES and COMPASS experiments. We observe that the obtained \begin{document}$ x_B$\end{document}-, \begin{document}$ z_h$\end{document}-, and \begin{document}$ P_{h\perp}$\end{document}-dependent Kotzinian-Mulders effects are basically consistent with the HERMES and COMPASS measurements. We also make predictions at EIC and EicC kinematics.
Toward discovering low-lying P-wave excited Σc baryon states
Kai-Lei Wang, Xian-Hui Zhong
2022, 46(2): 023103. doi: 10.1088/1674-1137/ac3123
Abstract:
In this study, by combining the equal spacing rule with recent observations of \begin{document}$ \Omega_c(X) $\end{document} and \begin{document}$ \Xi_c(X) $\end{document} baryons, we predict the spectrum of the low-lying \begin{document}$ \lambda $\end{document}-mode \begin{document}$ 1P $\end{document}-wave excited \begin{document}$ \Sigma_c $\end{document} states. Furthermore, their strong decay properties are predicted using the chiral quark model and the nature of \begin{document}$ \Sigma_c(2800) $\end{document} is investigated by analyzing the \begin{document}$ \Lambda_c\pi $\end{document} invariant mass spectrum. The \begin{document}$ \Sigma_c(2800) $\end{document} structure observed in the \begin{document}$ \Lambda_c \pi $\end{document} mass spectrum was found to potentially arise from two overlapping \begin{document}$ P $\end{document}-wave \begin{document}$ \Sigma_c $\end{document} resonances, \begin{document}$ \Sigma_c(2813)3/2^- $\end{document} and \begin{document}$ \Sigma_c(2840)5/2^- $\end{document}. These resonances have similar decay widths of \begin{document}$ \Gamma\sim 40 $\end{document} MeV and predominantly decay into the \begin{document}$ \Lambda_c \pi $\end{document} channel. The \begin{document}$ \Sigma_c(2755)1/2^- $\end{document} state is likely to be a very narrow state with a width of \begin{document}$ \Gamma\sim 15 $\end{document} MeV, with its decays almost saturated by the \begin{document}$ \Lambda_c \pi $\end{document} channel. Additionally, evidence of the \begin{document}$\Sigma_c(2755) {1}/{2}^-$\end{document} resonance as a very narrow peak may be seen in the \begin{document}$ \Lambda_c\pi $\end{document} invariant mass spectrum. The other two \begin{document}$ P $\end{document}-wave states, \begin{document}$\Sigma_c(2746) {1}/{2}^-$\end{document} and \begin{document}$\Sigma_c(2796) {3}/{2}^-$\end{document}, are relatively narrow states with similar widths of \begin{document}$ \Gamma\sim 30 $\end{document} MeV and predominantly decay into \begin{document}$ \Sigma_c\pi $\end{document} and \begin{document}$ \Sigma^{*}_c\pi $\end{document}, respectively. This study can provide useful references for discovering these low-lying \begin{document}$ P $\end{document}-wave states in forthcoming experiments.
An N/D study of the S11 channel πN scattering amplitude
Qu-Zhi Li, Yao Ma, Wen-Qi Niu, Yu-Fei Wang, Han-Qing Zheng
2022, 46(2): 023104. doi: 10.1088/1674-1137/ac31a4
Abstract:
Extensive dynamical \begin{document}$N/D$\end{document} calculations are conducted in the study of \begin{document}$S_{11}$\end{document} channel low energy \begin{document}$\pi N$\end{document} scatterings, based on various phenomenological model inputs of left cuts at the tree level. The subtleties of the singular behavior of the partial wave amplitude, at the origin of the complex \begin{document}$s$\end{document} plane, are analysed in detail. Furthermore, it is found that the dispersion representation for the phase shift, \begin{document}$\delta$\end{document}, must be modified in the case of \begin{document}$\pi N$\end{document} scatterings. An additional contribution from the dispersion integral exists, which approximately cancels the contribution of the two virtual poles located near the end points of the segment cut, induced by \begin{document}$u$\end{document} channel nucleon exchanges. With limited reliance on the details of the dynamical inputs, the subthreshold resonance \begin{document}$N^*(890)$\end{document} survives.
Possible dibaryon production at ${{\overline {\bf P} }}$anda with a Lagrangian approach
Yubing Dong, Pengnian Shen
2022, 46(2): 023105. doi: 10.1088/1674-1137/ac3567
Abstract:
In order to confirm the existence of the dibaryon state \begin{document}$ d^*(2380) $\end{document} observed at WASA@COSY, we estimate the cross section for production of the possible dibaryon and anti-dibaryon pair \begin{document}$ {d^*}{\bar{d}^*} $\end{document} in the energy region of the upcoming experiments at \begin{document}$ {\bar{{\rm{P}}}} $\end{document}anda. Based on some qualitative properties of \begin{document}$ {d^*} $\end{document} extracted from the analyses in the non-relativistic quark model, the production cross section for this spin-3 particle pair are calculated with the help of a phenomenological effective relativistic and covariant Lagrangian approach.
Photoproduction reaction γnK*0Λ in an effective Lagrangian approach
Neng-Chang Wei, Yi-Ming Zhu, Fei Huang
2022, 46(2): 023106. doi: 10.1088/1674-1137/ac3642
Abstract:
In our previous work [Phys. Rev. C 101, 014003 (2020)], the photoproduction reaction \begin{document}$\gamma p \to K^{\ast +} \Lambda$\end{document} was investigated within an effective Lagrangian approach. The reaction amplitudes were constructed by including the t-channel K, \begin{document}$K^\ast$\end{document}, and κ exchanges, u-channel Λ, Σ, and \begin{document}$\Sigma^\ast$\end{document} exchanges, s-channel N, \begin{document}$N(2000)5/2^+$\end{document}, and \begin{document}$N(2060)5/2^-$\end{document} exchanges, and interaction current. The data on the differential cross sections and spin density matrix elements were described simultaneously. In this study, we investigate the photoproduction reaction \begin{document}$\gamma n \to K^{\ast 0} \Lambda$\end{document} based on the same reaction mechanism as that of \begin{document}$\gamma p \to K^{\ast +} \Lambda$\end{document} to obtain a unified description of the data for \begin{document}$\gamma p \to K^{\ast +} \Lambda$\end{document} and \begin{document}$\gamma n \to K^{\ast 0} \Lambda$\end{document} within the same model. All hadronic coupling constants, form factor cutoffs, and the resonance masses and widths in the present calculations remain the same as in our previous work for \begin{document}$\gamma p \to K^{\ast +} \Lambda$\end{document}. The available differential cross-section data for \begin{document}$\gamma n \to K^{\ast 0} \Lambda$\end{document} are well reproduced. Further analysis shows that the cross sections of \begin{document}$\gamma n \to K^{\ast 0} \Lambda$\end{document} are dominated by the contributions of the t-channel K exchange, while the s-channel \begin{document}$N(2000)5/2^+$\end{document} and \begin{document}$N(2060)5/2^-$\end{document} exchanges also provide considerable contributions.
Pure annihilation decay of strange beauty meson into two charm heavy mesons
Behnam Mohammadi
2022, 46(2): 023107. doi: 10.1088/1674-1137/ac3a5a
Abstract:
In this study, the heavy to heavy decay of \begin{document}$ B^0_s\rightarrow D^{*+}D^- $\end{document} is evaluated through the factorization approach by using the final state interaction as an effective correction. Under the factorization approach, this decay mode occurs only through the annihilation process, so a small amount is produced. Feynman's rules state that six meson pairs can be assumed for the intermediate states before the final meson pairs are produced. By taking into account the effects of twelve final state interaction diagrams in the calculations, a significant correction is obtained. These effects correct the value of the branching ratio obtained by the pure factorization approach from \begin{document}$ (2.41\pm1.37)\times10^{-5} $\end{document} to \begin{document}$ (8.27\pm2.23)\times10^{-5} $\end{document}. The value obtained for the branching ratio of the \begin{document}$ B^0_s\rightarrow D^{*+}D^- $\end{document} decay is consistent with the experimental results.
NUCLEAR PHYSICS
Cross-section measurements for the 58,60,61Ni(n, α)55,57,58Fe reactions at 8.50, 9.50 and 10.50 MeV neutron energies
Haoyu Jiang, Zengqi Cui, Yiwei Hu, Jie Liu, Haofan Bai, Jinxiang Chen, Guohui Zhang, Yu. M. Gledenov, E. Sansarbayar, G. Khuukhenkhuu, L. Krupa, I. Chuprakov, Xichao Ruan, Hanxiong Huang, Jie Ren, Qiwen Fan
2022, 46(2): 024001. doi: 10.1088/1674-1137/ac3412
Abstract:
Cross sections of the 58,60,61Ni(n, α)55,57,58Fe reactions were measured at 8.50, 9.50 and 10.50 MeV neutron energies based on the HI-13 tandem accelerator of China Institute of Atomic Energy (CIAE) with enriched 58Ni, 60Ni, and 61Ni foil samples with backings. A twin gridded ionization chamber (GIC) was used as the charged particle detector, and an EJ-309 liquid scintillator was used to obtain the neutron energy spectra. The relative and absolute neutron fluxes were determined via three highly enriched 238U3O8 samples inside the GIC. The uncertainty of the present data of the 58Ni(n, α)55Fe reaction is smaller than most existing measurements. The present data of 60Ni(n, α)57Fe and 61Ni(n, α)58Fe reactions are the first measurement results above 8 MeV. The present experimental data could be reasonably reproduced by calculations with TALYS-1.9 by adjusting several default values of theoretical model parameters.
Theoretical predictions on α-decay properties of some unknown neutron-deficient actinide nuclei using machine learning
Ziyi Yuan, Dong Bai, Zhongzhou Ren, Zhen Wang
2022, 46(2): 024101. doi: 10.1088/1674-1137/ac321c
Abstract:
Neutron-deficient actinide nuclei provide a valuable window to probe heavy nuclear systems with large proton-neutron ratios. In recent years, several new neutron-deficient Uranium and Neptunium isotopes have been observed using α-decay spectroscopy [Z. Y. Zhang et al., Phys. Rev. Lett. 122, 192503 (2019); L. Ma et al., Phys. Rev. Lett. 125, 032502 (2020); Z. Y. Zhang et al., Phys. Rev. Lett. 126, 152502 (2021)]. In spite of these achievements, some neutron-deficient key nuclei in this mass region are still unknown in experiments. Machine learning algorithms have been applied successfully in different branches of modern physics. It is interesting to explore their applicability in α-decay studies. In this work, we propose a new model to predict the α-decay energies and half-lives within the framework based on a machine learning algorithm called the Gaussian process. We first calculate the α-decay properties of the new actinide nucleus \begin{document}$ {}^{214}{\rm{U}}$\end{document}. The theoretical results show good agreement with the latest experimental data, which demonstrates the reliability of our model. We further use the model to predict the α-decay properties of some unknown neutron-deficient actinide isotopes and compare the results with traditional models. The results may be useful for future synthesis and identification of these unknown isotopes.
Mass splitting of vector mesons and spontaneous spin polarization under rotation
Minghua Wei, Yin Jiang, Mei Huang
2022, 46(2): 024102. doi: 10.1088/1674-1137/ac338e
Abstract:
In this study, we investigate the effect of rotation on the masses of scalar and vector mesons in the framework of the 2-flavor Nambu-Jona-Lasinio model. The existence of rotation produces a tedious quark propagator and a corresponding polarization function. By applying the random phase approximation, the meson mass is numerically calculated. It is found that the behavior of scalar and pseudoscalar meson masses under angular velocity ω is similar to that at a finite chemical potential; both rely on the behavior of the constituent quark mass and reflect the property related to chiral symmetry. However, vector meson ρ masses have a more profound relation to rotation. After analytical and numerical calculations, it turns out that at low temperature and small chemical potential, the mass for spin component \begin{document}$ s_z = 0,\pm 1 $\end{document} of a vector meson under rotation exhibits a very simple mass splitting relation \begin{document}$ m_{\rho}^{s_z}(\omega) = m_\rho(\omega = 0)-\omega s_z $\end{document}, similar to the Zeeman splitting of a charged meson under magnetic fields. Furthermore, the mass of the spin component \begin{document}$ s_z = 1 $\end{document} of vector meson ρ decreases linearly with ω and reaches zero at \begin{document}$ \omega_c = m_\rho(\omega = 0) $\end{document}, which indicates that the system will develop \begin{document}$ s_z = 1 $\end{document} vector meson condensation and the system will be spontaneously spin-polarized under rotation.
Energy density functional analysis of the fission properties of 240Pu: The effect of pairing correlations
Yong-Jing Chen, Yang Su, Guoxiang Dong, Li-Le Liu, Zhigang Ge, Xiaobao Wang
2022, 46(2): 024103. doi: 10.1088/1674-1137/ac347a
Abstract:
We have calculated the potential energy surfaces for 240Pu up to the scission point using the density functional theory with different pairing strengths to investigate the effect of pairing correlations on its fission properties. An enhancement in the pairing correlations lowers the barrier heights, isomeric state, and ridge between the symmetric and asymmetric fission valleys significantly. Moreover, it weakens the microscopic shell structure around the Fermi surface, shrinks the scission frontiers, especially for the symmetric and very asymmetric fission regions, and lifts the total kinetic energies (TKEs) for the symmetric fission region. It is also emphasized that the microscopic calculation qualitatively reproduces the trend of the distribution of the measured TKEs, especially for the positions of the peaks at \begin{document}$A_{\rm{frag}}\simeq132$\end{document} and \begin{document}$A_{\rm{frag}}\simeq108$\end{document}.
Fixed point behavior of cumulants in the three-dimensional Ising universality class
Xue Pan
2022, 46(2): 024104. doi: 10.1088/1674-1137/ac3748
Abstract:
High-order cumulants and factorial cumulants of conserved charges are suggested for the study of the critical dynamics in heavy-ion collision experiments. In this paper, using the parametric representation of the three-dimensional Ising model which is believed to belong to the same universality class as quantum chromo-dynamics, the temperature dependence of the second- to fourth-order (factorial) cumulants of the order parameter is studied. It is found that the values of the normalized cumulants are independent of the external magnetic field at the critical temperature, which results in a fixed point in the temperature dependence of the normalized cumulants. In finite-size systems simulated using the Monte Carlo method, this fixed point behavior still exists at temperatures near the critical. This fixed point behavior has also appeared in the temperature dependence of normalized factorial cumulants from at least the fourth order. With a mapping from the Ising model to QCD, the fixed point behavior is also found in the energy dependence of the normalized cumulants (or fourth-order factorial cumulants) along different freeze-out curves.
Pauli blocking potential applied to heavy-ion fusion reactions
Kai-Xuan Cheng, Chang Xu, Chun-Wang Ma, Jie Pu, Yu-Ting Wang
2022, 46(2): 024105. doi: 10.1088/1674-1137/ac3749
Abstract:
In this study, the Pauli blocking potential between two colliding nuclei in the density overlapping region is applied to describe the heavy nuclei fusion process. Inspired by the Pauli blocking effect in the \begin{document}$ \alpha $\end{document}-decay of heavy nuclei, the Pauli blocking potential of single nucleon from the surrounding matter is obtained. In fusion reactions with strong density overlap, the Pauli blocking potential between the projectile and target can be constructed using a single folding model. By considering this potential, the double folding model with a new parameter set is employed to analyze the fusion processes of 95 systems. A wider Coulomb barrier and shallower potential pocket are formed in the inner part of the potential between the two colliding nuclei, compared to that calculated using the Akyüz-Winther potential. The fusion hindrance phenomena at deep sub-barrier energies are described well for fusion systems \begin{document}$ ^{16} $\end{document}O + \begin{document}$ ^{208} $\end{document}Pb and \begin{document}$ ^{58} $\end{document}Ni + \begin{document}$ ^{58} $\end{document}Ni.
Quantum computing for the Lipkin model with unitary coupled cluster and structure learning ansatz
Asahi Chikaoka, Haozhao Liang
2022, 46(2): 024106. doi: 10.1088/1674-1137/ac380a
Abstract:
We report a benchmark calculation for the Lipkin model in nuclear physics with a variational quantum eigensolver in quantum computing. Special attention is paid to the unitary coupled cluster (UCC) ansatz and structure learning (SL) ansatz for the trial wave function. Calculations with both the UCC and SL ansatz can reproduce the ground-state energy well; however, it is found that the calculation with the SL ansatz performs better than that with the UCC ansatz, and the SL ansatz has even fewer quantum gates than the UCC ansatz.
Microscopic study of higher-order deformation effects on the ground states of superheavy nuclei around 270Hs
Xiao-Qian Wang, Xiang-Xiang Sun, Shan-Gui Zhou
2022, 46(2): 024107. doi: 10.1088/1674-1137/ac3904
Abstract:
We investigate the effects of higher-order deformations \begin{document}$\beta_\lambda$\end{document} (\begin{document}$\lambda=4,6,8,$\end{document} and 10) on the ground state properties of superheavy nuclei (SHN) near the doubly magic deformed nucleus \begin{document}$^{270}{\rm{Hs}}$\end{document} using the multidimensionally-constrained relativistic mean-field (MDC-RMF) model with five effective interactions: PC-PK1, PK1, NL3*, DD-ME2, and PKDD. The doubly magic properties of \begin{document}$^{270}{\rm{Hs}}$\end{document} include large energy gaps at \begin{document}$N=162$\end{document} and \begin{document}$Z=108$\end{document} in the single-particle spectra. By investigating the binding energies and single-particle levels of \begin{document}$^{270}{\rm{Hs}}$\end{document} in the multidimensional deformation space, we find that, among these higher-order deformations, the deformation \begin{document}$\beta_6$\end{document} has the greatest impact on the binding energy and influences the shell gaps considerably. Similar conclusions hold for other SHN near \begin{document}$^{270}{\rm{Hs}}$\end{document}. Our calculations demonstrate that the deformation \begin{document}$\beta_6$\end{document} must be considered when studying SHN using MDC-RMF.
Equal-time kinetic equations in a rotational field
Shile Chen, Ziyue Wang, Pengfei Zhuang
2022, 46(2): 024108. doi: 10.1088/1674-1137/ac39fd
Abstract:
We investigate quantum kinetic theory for a massive fermion system under a rotational field. From the Dirac equation in rotating frame we derive the complete set of kinetic equations for the spin components of the 8- and 7-dimensional Wigner functions. While the particles are no longer on a mass shell in the general case due to the rotation–spin coupling, there are always only two independent components, which can be taken as the number and spin densities. With help from the off-shell constraint we obtain the closed transport equations for the two independent components in the classical limit and at the quantum level. The classical rotation–orbital coupling controls the dynamical evolution of the number density, but the quantum rotation–spin coupling explicitly changes the spin density.
η mesons in hot magnetized nuclear matter
Rajesh Kumar, Arvind Kumar
2022, 46(2): 024109. doi: 10.1088/1674-1137/ac3bc7
Abstract:
\begin{document}$\eta N$\end{document} interactions are investigated in hot magnetized asymmetric nuclear matter using the chiral SU(3) model and chiral perturbation theory (ChPT). In the chiral model, the in-medium properties of η-mesons are calculated using medium modified scalar densities under the influence of an external magnetic field. Further, in a combined chiral model and ChPT approach, off-shell contributions of the \begin{document}$\eta N$\end{document} interactions are evaluated from the ChPT effective \begin{document}$\eta N$\end{document} Lagrangian, and the in-medium effect of scalar densities are incorporated from the chiral SU(3) model. We find that the magnetic field has a significant effect on the in-medium mass and optical potential of η mesons, and we observe a deeper mass-shift in the combined chiral model and ChPT approach than in the solo chiral SU(3) model. In both approaches, no additional mass-shift is observed due to the uncharged nature of η mesons in the presence of a magnetic field.
PARTICLE AND NUCLEAR ASTROPHYSICS AND COSMOLOGY
Gravitational leptogenesis in teleparallel and symmetric teleparallel gravities
Mingzhe Li, Yicen Mou, Haomin Rao, Dehao Zhao
2022, 46(2): 025101. doi: 10.1088/1674-1137/ac3411
Abstract:
In this study, we investigate the possibilities of generating baryon number asymmetry under thermal equilibrium within the frameworks of teleparallel and symmetric teleparallel gravities. Through the derivative couplings of the torsion scalar and the non-metricity scalar to baryons, baryon number asymmetry is produced in the radiation dominated epoch. For gravitational baryogenesis mechanisms in these two frameworks, the produced baryon-to-entropy ratio is too small to be consistent with observations. However, the gravitational leptogenesis models within both frameworks have the potential to explain the observed baryon-antibaryon asymmetry.
Modified regular black holes with time delay and 1-loop quantum correction
Yi Ling, Meng-He Wu
2022, 46(2): 025102. doi: 10.1088/1674-1137/ac3643
Abstract:
We develop the regular black hole solutions by incorporating the 1-loop quantum correction to the Newton potential and a time delay between an observer at the regular center and one at infinity. We define the maximal time delay between the center and the infinity by scanning the mass of black holes such that the sub-Planckian feature of the Kretschmann scalar curvature is preserved during the process of evaporation. We also compare the distinct behavior of the Kretschmann curvature for black holes with asymptotically Minkowski cores and those with asymptotically de-Sitter cores, including Bardeen and Hayward black holes. We expect that such regular black holes may provide more information about the construction of effective metrics for Planck stars.