2022 Vol. 46, No. 10

Display Method:          |     

A unique gravitational wave signal from phase transition during inflation
Haipeng An, Kun-Feng Lyu, Lian-Tao Wang, Siyi Zhou
2022, 46(10): 101001. doi: 10.1088/1674-1137/ac76a7
We study the properties of gravitational wave (GW) signals produced by first-order phase transitions during the inflation era. We show that the power spectrum of a GW oscillates with its wave number. This signal can be observed directly by future terrestrial and spatial GW detectors and through the B-mode spectrum in the CMB. This oscillatory feature of the GW is generic for any approximately instantaneous sources occurring during inflation and is distinct from the GW from phase transitions after inflation. The details of the GW spectrum contain information about the scale of the phase transition and the later evolution of the universe.
Study of background from accidental coincidence signalsin the PandaX-II experiment
Abdusalam Abdukerim, Wei Chen, Xun Chen, Yunhua Chen, Chen Cheng, Xiangyi Cui, Yingjie Fan, Deqing Fang, Changbo Fu, Mengting Fu, Lisheng Geng, Karl Giboni, Linhui Gu, Xuyuan Guo, Ke Han, Changda He, Di Huang, Yan Huang, Yanlin Huang, Zhou Huang, Xiangdong Ji, Yonglin Ju, Shuaijie Li, Huaxuan Liu, Jianglai Liu, Wenbo Ma, Yugang Ma, Yajun Mao, Yue Meng, Kaixiang Ni, Jinhua Ning, Xuyang Ning, Xiangxiang Ren, Changsong Shang, Lin Si, Guofang Shen, Andi Tan, Anqing Wang, Hongwei Wang, Meng Wang, Qiuhong Wang, Siguang Wang, Wei Wang, Xiuli Wang, Zhou Wang, Mengmeng Wu, Shiyong Wu, Weihao Wu, Jingkai Xia, Mengjiao Xiao, Pengwei Xie, Binbin Yan, Jijun Yang, Yong Yang, Chunxu Yu, Jumin Yuan, Ying Yuan, Xinning Zeng, Dan Zhang, Tao Zhang, Li Zhao, Qibin Zheng, Jifang Zhou, Ning Zhou, Xiaopeng Zhou, (PandaX-II Collaboration)
2022, 46(10): 103001. doi: 10.1088/1674-1137/ac7cd8
Lepton and quark mixing patterns with generalized CP transformations
Joy Ganguly, Raghavendra Srikanth Hundi
2022, 46(10): 103101. doi: 10.1088/1674-1137/ac763c
In this study, we modify a scenario, originally proposed by Grimus and Lavoura, in order to obtain maximal values for the atmospheric mixing angle and \begin{document}$C P$\end{document}, violating the Dirac phase of the lepton sector. To achieve this, we employ \begin{document}$C P$\end{document} and some discrete symmetries in a type II seesaw model. To make predictions about the neutrino mass ordering and smallness of the reactor angle, we establish some conditions on the elements of the neutrino mass matrix of our model. Finally, we study the quark masses and mixing pattern within the framework of our model.
Spectroscopic study of strangeness = –3 Ω baryon
Chandni Menapara, Ajay Kumar Rai
2022, 46(10): 103102. doi: 10.1088/1674-1137/ac78d1
\begin{document}$ \Omega^{-} $\end{document} baryon with sss quarks has been investigated through many theoretical studies so far but scarcely observed in experiments. Here, an attempt has been made to explore properties of Ω with hypercentral Constituent Quark Model (hCQM) with a linear confining term. The resonance mass spectra have been obtained for 1S–4S, 1P–4P, 1D–3D, and 1F–2F. The Regge trajectory has been investigated for the linear nature based on calculated data along with the magnetic moment. The present work has been compared with various approaches and known experimental findings.
Search for single production of vectorlike B-quarks at the LHC
Jin-Zhong Han, Yao-Bei Liu, Lu Xing, Shuai Xu
2022, 46(10): 103103. doi: 10.1088/1674-1137/ac79ab
New vectorlike quarks have been proposed in many scenarios of new physics beyond the Standard Model, which address the hierarchy problem and may be potentially discovered at the Large Hadron Collider (LHC). Based on a model-independent framework, we propose to search for the vectorlike B-quark (VLQ-B) and focus on resonant production via b-gluon fusion through chromomagnetic interactions. We then explore the possible signals of the VLQ-B through the \begin{document}$ B\to tW $\end{document} decay mode at the 14 TeV LHC. After a rapid simulation of signal and background events, the \begin{document}$ 2\sigma $\end{document} excluded regions and the \begin{document}$ 5\sigma $\end{document} discovery reach in the parameter plane of \begin{document}$ \kappa_{B}-M_B $\end{document}are obtained at the LHC with an integrated luminosity of 300 (3000) fb\begin{document}$ ^{-1} $\end{document}in the dilepton final states.
General one-loop reduction in generalized Feynman parametrization form
Hongbin Wang
2022, 46(10): 103104. doi: 10.1088/1674-1137/ac7a1c
The search for an effective reduction method is one of the main topics in higher loop computation. Recently, an alternative reduction method was proposed by Chen in [1, 2]. In this paper, we test the power of Chen's new method using one-loop scalar integrals with propagators of higher power. More explicitly, with the improved version of the method, we can cancel the dimension shift and terms with unwanted power shifting. Thus, the obtained integrating-by-parts relations are significantly simpler and can be solved easily. Using this method, we present explicit examples of a bubble, triangle, box, and pentagon with one doubled propagator. With these results, we complete our previous computations in [3] with the missing tadpole coefficients and show the potential of Chen's method for efficient reduction in higher loop integrals.
Joint explanation of W-mass and muon g–2 in the 2HDM
Xiao-Fang Han, Fei Wang, Lei Wang, Jin-Min Yang, Yang Zhang
2022, 46(10): 103105. doi: 10.1088/1674-1137/ac7c63
Because both W-mass and muon \begin{document}$ g-2 $\end{document} can be affected by mass splittings among extra Higgs bosons \begin{document}$ (H,\; A,\; H^\pm) $\end{document} in a two-Higgs-doublet model, we take a model with μ-τ lepton flavor violation interactions to examine the two anomalies reported by CDF II and FNAL. We obtain the following observations: (i) Combined with theoretical constraints, the CDF W-mass measurement disfavors H or A degenerating in mass with \begin{document}$ H^\pm $\end{document} but allows H and A to degenerate. The mass splitting between \begin{document}$ H^\pm $\end{document} and \begin{document}$ H/A $\end{document} must be larger than 10 GeV. \begin{document}$ m_{H^\pm} $\end{document} and \begin{document}$ m_{A} $\end{document} are favored to be smaller than 650 GeV for \begin{document}$ m_H<120 $\end{document} GeV and allowed to have larger values with increasing \begin{document}$ m_H $\end{document} . (ii) After imposing other relevant experimental constraints, there are parameter spaces that simultaneously satisfy (at the \begin{document}$ 2\sigma $\end{document} level) the CDF W-mass, FNAL muon \begin{document}$ g-2 $\end{document}, and data on lepton universality in τ decays; however, the mass splittings among extra Higgs bosons are strictly constrained.
Decay widths of Zcs(3985/4000) based on rigorous quark-hadron duality
Zhi-Gang Wang
2022, 46(10): 103106. doi: 10.1088/1674-1137/ac7cd7
In this study, we explore the hadronic coupling constants \begin{document}$ G_{ZJ/\psi K} $\end{document}, \begin{document}$ G_{Z\eta_c K^*} $\end{document}, and \begin{document}$ G_{ZD^* \bar{D}_s} $\end{document} of the exotic states \begin{document}$ Z_{cs}(3985/4000) $\end{document} within the pictures of both the tetraquark and molecular states with the tentative assignments \begin{document}$ J^{PC}=1^{+-} $\end{document} based on rigorous quark-hadron duality. Subsequently, we obtain the total widths \begin{document}$ \Gamma_{Z_{cs}}^T =15.31\pm 2.06\,{\rm{MeV}} $\end{document} and \begin{document}$ \Gamma_{Z_{cs}}^M=83.51\pm21.09\,{\rm{MeV}} $\end{document}, which are consistent with experimental values from the BESIII collaboration, \begin{document}$ 13.8^{+8.1}_{-5.2}\pm4.9\,{\rm{MeV}} $\end{document}, and LHCb collaboration, \begin{document}$ 131 \pm 15 \pm 26\,{\rm{MeV}} $\end{document}, respectively, and support assigning \begin{document}$ Z_{cs}(3985) $\end{document} and \begin{document}$ Z_{cs}(4000) $\end{document} as the hidden-charm tetraquark and molecular states with \begin{document}$ J^{PC}=1^{+-} $\end{document}, respectively.
Nonextensive effects on QCD chiral phase transition with a chiral chemical potential
Ya-Peng Zhao, Shu-Yu Zuo, Cheng-Ming Li
2022, 46(10): 103107. doi: 10.1088/1674-1137/ac5dbc
In this study, we investigate the QCD chiral phase diagram in the presence of a chiral chemical potential \begin{document}$ \mu_{5} $\end{document} based on nonextensive statistical mechanics. A feature of this new statistic is a dimensionless nonextensivity parameter q, which summarizes all possible effects violating the assumptions of Boltzmann-Gibbs (BG) statistics (when \begin{document}$ q\rightarrow1 $\end{document}, it returns to the BG case). Within the nonextensive Polyakov-Nambu-Jona-Lasinio model, we find that as \begin{document}$ \mu_{5} $\end{document} increases, the critical end point (CEP) in the \begin{document}$ T-\mu $\end{document} plane continues to \begin{document}$ \mathrm{CEP}_{5} $\end{document} in the \begin{document}$ T-\mu_{5} $\end{document} plane, and nonextensive effects have a significant impact on the evolution from the CEP to \begin{document}$ \mathrm{CEP}_{5} $\end{document}. Generally, with an increase in q, both the CEP and \begin{document}$ \mathrm{CEP}_{5} $\end{document} move in the direction of a lower temperature T and larger chemical potential μ (\begin{document}$ \mu_{5} $\end{document}). In addition, we find that chiral charge density \begin{document}$ n_{5} $\end{document} generally increases with T, μ, \begin{document}$ \mu_{5} $\end{document}, and q. Our study may provide useful hints about lattice QCD and relativistic heavy-ion collision experiments.
Measuring CP violation in rare W decays at the LHC
Peng-Cheng Lu, Zong-Guo Si, Zhe Wang, Xing-Hua Yang
2022, 46(10): 103108. doi: 10.1088/1674-1137/ac7eb2
Heavy Majorana neutrinos beyond the standard model can simultaneously explain the origin of tiny neutrino masses and matter-antimatter asymmetry in our Universe. The existence of heavy Majorana neutrinos will also lead to lepton number violation and confirm the possibility of rare lepton-number-violating W decays. With contributions from two different Majorana neutrinos, nonzero CP asymmetry may be generated from the rate difference between W decay and its CP-conjugate process. The aim of this study is to investigate the prospects of measuring CP violation in rare W decays via Majorana neutrinos at the LHC. Our calculations show that the induced CP asymmetry is independent of the Majorana neutrino mass for \begin{document}$ 15 < {m}_{N}^{} < 70\; {{\rm{GeV}}} $\end{document}. Such a CP asymmetry, if observed, would in turn provide unambiguous evidence of new physics beyond the standard model.
Studies of the 2α and 3α channels of the 12C+12C reaction in the range of Ec.m.=8.9 MeV to 21 MeV using the active target Time Projection Chamber
X. Y. Wang, N. T. Zhang, Z. C. Zhang, C. G. Lu, T. L. Pu, J. L. Zhang, L. M. Duan, B. S. Gao, K. A. Li, Y. T. Li, Y. Qian, L. H. Ru, B. Wang, X. D. Xu, H. Y. Zhao, W. P. Lin, Z. W. Cai, B. F. Ji, Q. T. Li, J. Y. Xu, X. D. Tang
2022, 46(10): 104001. doi: 10.1088/1674-1137/ac7a1d
The 12C+12C fusion reaction was studied in the range of Ec.m.=8.9 to 21 MeV using the active-target Time Projection Chamber. With full information on all tracks of the reaction products, cross sections of the 12C(12C,8Be)16Og.s. channel and the 12C(12C,3α)12C channel could be measured down to the level of a few milibarns. The 12C(12C,8Be)16Og.s. reaction channel was determined to be 10 \begin{document}$ _{-8}^{+24} $\end{document} mb at Ec.m.=11.1 MeV, supporting the direct α transfer reaction mechanism. The 12C(12C,3α)12C reaction channel was studied for the first time using an exclusive measurement. Our result does not confirm the anomaly behavior reported in the previous inclusive measurement by Kolata et al. [Phys. Rev. C 21, 579 (1980)]. Our comparisons with statistical model calculations suggest that the 3α channel is dominated by the fusion evaporation process at Ec.m. > 19 MeV. The additional contribution of the 3α channel increases the fusion reaction cross section by 10% at energies above 20 MeV. We also find that an additional reaction mechanism is needed to explain the measured cross section at Ec.m. < 15 MeV at which point the statistical model prediction vanishes.
Spectral fluctuations in the interacting boson model
Yu-Qing Wu, Wei Teng, Xiao-Jie Hou, Gui-Xiu Na, Yu Zhang, Bing-Cheng He, Yan-An Luo
2022, 46(10): 104101. doi: 10.1088/1674-1137/ac76a5
The energy dependence of the spectral fluctuations in the interacting boson model (IBM) and its connections to the mean-field structures are analyzed by adopting two statistical measures: the nearest neighbor level spacing distribution \begin{document}$ P(S)$\end{document} measuring the chaoticity (regularity) in energy spectra and the \begin{document}$ \Delta_3(L)$\end{document} statistics of Dyson and Metha measuring the spectral rigidity. Specifically, the statistical results as functions of the energy cutoff are determined for different dynamical scenarios, including the U(5)-SU(3) and SU(3)-O(6) transitions as well as those near the AW arc of regularity. We observe that most of the changes in spectral fluctuations are triggered near the stationary points of the classical potential, particularly for cases in the deformed region of the IBM phase diagram. Thus, the results justify the stationary point effects from the perspective of statistics. In addition, the approximate degeneracies in the \begin{document}$ 2^+$\end{document} spectrum on the AW arc is also revealed from the statistical calculations.
pT dispersion of inclusive jets in high-energy nuclear collisions
Shi-Yong Chen, Jun Yan, Wei Dai, Ben-Wei Zhang, En-Ke Wang
2022, 46(10): 104102. doi: 10.1088/1674-1137/ac79aa
In this study, we investigate the impact of jet quenching on the \begin{document}$ p_{T} $\end{document} dispersion (\begin{document}$ p_{T}D $\end{document}) of inclusive jets (\begin{document}$ R=0.2 $\end{document}) in central Pb+Pb (0%–10%) collisions at \begin{document}$ \sqrt{s}=2.76 $\end{document} TeV. The partonic spectrum in the initial hard scattering of elementary collisions is obtained by an event generator POWHEG+PYTHIA, which matches the next-to-leading order (NLO) matrix elements with parton showering, and the energy loss of a fast parton traversing through hot/dense QCD medium is calculated using Monte Carlo simulation within the Higher-Twist formalism of jet quenching in heavy-ion collisions. We present model calculations of the normalized \begin{document}$ p_{T}D $\end{document} distributions of inclusive jets in p+p and central Pb+Pb collisions at \begin{document}$ \sqrt{s}=2.76 $\end{document} TeV, which offer good descriptions of ALICE measurements. It is shown that the \begin{document}$ p_{T}D $\end{document} distributions of inclusive jets in central Pb+Pb collisions shift significantly to a higher \begin{document}$ p_{T}D $\end{document} region relative to those in p+p collisions. Thus, the nuclear modification ratio of the \begin{document}$ p_{T}D $\end{document} distributions of inclusive jets is smaller than unity in the small \begin{document}$ p_{T}D $\end{document} region and larger than one in the large \begin{document}$ p_{T}D $\end{document} region. This behavior is caused by a more uneven \begin{document}$ p_T $\end{document} distribution for jet constituents as well as the fraction alteration of quark/gluon initiated jets in heavy-ion collisions. The difference in \begin{document}$ p_{T}D $\end{document} distribution between groomed and ungroomed jets in Pb+Pb collisions is also discussed.
Three-body Faddeev calculations for ${{}_{\boldsymbol\Lambda \boldsymbol\Lambda }^{\;\;\;\;\bf 6}{\bf{He}}}$ and ${{}_{\boldsymbol\Omega \boldsymbol\Omega }^{\;\;\;\;\bf 6}{\bf{He}}} $ hypernuclei
Faisal Etminan, M. R. Hadizadeh
2022, 46(10): 104103. doi: 10.1088/1674-1137/ac7a22
We study the ground-state properties of the\begin{document}$ {}_{YY }^{\;\;\;6}{\rm{He}} $\end{document} double hyperon for \begin{document}$ {}_{\Lambda\Lambda }^{\;\;\;6}{\rm{He}} $\end{document} and \begin{document}$ {}_{\Omega\Omega }^{\;\;\;6}{\rm{He}} $\end{document}nuclei in a three-body model \begin{document}$ (Y+Y+\alpha) $\end{document}. We solve two coupled Faddeev equations corresponding to the three-body configurations \begin{document}$ (\alpha Y, Y) $\end{document} and \begin{document}$ (YY, \alpha) $\end{document} in configuration space with the hyperspherical harmonics expansion method by employing the most recent hyperon-hyperon interactions obtained from lattice QCD simulations. Our numerical analysis for \begin{document}$ {}_{\Lambda\Lambda }^{\;\;\;6}{\rm{He}} $\end{document}, using three \begin{document}$ \Lambda\Lambda $\end{document} lattice interaction models, leads to a ground state binding energy in the \begin{document}$ (-7.468, -7.804) $\end{document}MeV domain and the separations \begin{document}$ \langle r_{\Lambda-\Lambda} \rangle $\end{document}and \begin{document}$ \langle r_{\alpha-\Lambda} \rangle $\end{document} in the domains of\begin{document}$ (3.555, 3.629) $\end{document} fm and \begin{document}$ (2.867 , 2.902 ) $\end{document} fm, respectively. The binding energy of the double-\begin{document}$ \Omega $\end{document} hypernucleus \begin{document}$ {}_{\Omega\Omega }^{\;\;\;6}{\rm{He}} $\end{document} leads to \begin{document}$ -67.21 $\end{document} MeV and consequently to smaller separations \begin{document}$ \langle r_{\Omega-\Omega} \rangle = 1.521 $\end{document} fm and \begin{document}$ \langle r_{\alpha-\Omega} \rangle = 1.293 $\end{document} fm. In addition to geometrical properties, we study the structure of ground-state wave functions and show that the main contributions are from the \begin{document}$ s- $\end{document}wave channels. Our results are consistent with the existing theoretical and experimental data.
Systematic study of proton radioactivity half-lives based on the relationship between Skyrme-Hartree-Fock and the macroscopic quantities of nuclear matter
Jun-Hao Cheng, Zhen Zhang, Xi-Jun Wu, Peng-Cheng Chu, Xiao-Hua Li
2022, 46(10): 104104. doi: 10.1088/1674-1137/ac7a99
In this study, we systematically investigate the proton radioactivity half-lives of 33 spherical nuclei based on the relationship between Skyrme parameters and the macroscopic quantities of nuclear matter. Using the two-potential approach with the spherical Skyrme-Hartree-Fock model, the correlation between proton radioactivity half-life and the macroscopic quantities is analyzed. Moreover, we obtain a new Skyrme parameter set by fitting the two most weighted macroscopic quantities. Compared with the Skyrme parameters MSL0 and the theoretical model of proton radioactivity UDLP, the theoretical proton radioactivity half-life calculated using the new Skyrme parameter set can better reproduce the experimental data.
A Global Weizsäcker mass model with relativistic mean field shell correction
W. Zhang, Z. Y. Li, W. Gao, T. T. Sun
2022, 46(10): 104105. doi: 10.1088/1674-1137/ac7b18
A relativistic Weizsäcker mass model is proposed based on the single-particle levels and ground state deformations obtained in axial deformed relativistic mean field theory. The density functional of relativistic mean field theory is chosen as DD-LZ1, which can partially remove spurious shell closures. Compared with the fourth Weizsäcker-Skyrme mass model, the proposed model provides shell correction energies that exhibit wide spreading, and the root-mean-square mass deviation is 1.353 MeV. Further improvement is in progress.
Particle production at large pT in Xe+Xe collisions with jet quenching using the higher twist approach
Qing Zhang, Wei Dai, Lei Wang, Ben-Wei Zhang, Enke Wang
2022, 46(10): 104106. doi: 10.1088/1674-1137/ac7b75
The production of \begin{document}$ \pi^0 $\end{document}, η, and ϕ in the most central (0%–5%) Xe+Xe collisions at \begin{document}$\sqrt{s_{NN}}$\end{document} = 5.44 TeV is investigated in the framework of the perturbative QCD (pQCD) improved parton model at an accuracy of next-to-leading order (NLO). The jet quenching effect is effectively incorporated by medium-modified fragmentation functions via the higher-twist approach. Predictions of the nuclear modification factors of \begin{document}$ \pi^0 $\end{document}, η, and ϕ as functions of the transverse momentum \begin{document}$ p_{\rm{T}} $\end{document} are made with the jet transport parameter \begin{document}$ \hat{q}_0 $\end{document}, which is extracted from the available experimental data of charged hadrons provided by ALICE and CMS. The particle ratios \begin{document}$ \eta/\pi^0,\ \phi/\pi^0 $\end{document} as functions of \begin{document}$ p_{\rm{T}} $\end{document} in Xe+Xe collisions at \begin{document}$\sqrt{s_{NN}}$\end{document} = 5.44 TeV as well as in 0%–5% Pb + Pb collisions at \begin{document}$\sqrt{s_{NN}}$\end{document} = 5.02 TeV are also presented. The numerical simulations of the scaled ratios of charged hadron production in the Xe+Xe 5.44 TeV system over those in the Pb+Pb 5.02 TeV system give a good description of the CMS data, and the scaled ratios of \begin{document}$ \pi^0 $\end{document}, η, and ϕ production coincide with the curve of charged hadron production.
Holographic Schwinger effect in a rotating strongly coupled medium
Yi-Ze Cai, Rui-Ping Jing, Zi-Qiang Zhang
2022, 46(10): 104107. doi: 10.1088/1674-1137/ac7cd9
We perform a potential analysis on the holographic Schwinger effect in a rotating deformed AdS black-hole background. We calculate the total potential of a quark-antiquark (\begin{document}$Q\bar{Q}$\end{document}) pair in an external electric field and evaluate the critical electric field from Dirac-Born-Infeld action. It is shown that the inclusion of angular velocity decreases the potential barrier, thus enhancing the Schwinger effect, which contrasts with the effect of the confining scale. Moreover, increasing the angular velocity decreases the critical electric field, above which these pairs are produced freely without suppression. Furthermore, we conclude that \begin{document}$Q\bar{Q}$\end{document} pair production would be easier in a rotating medium.
Discovery of new characterizations of parameter distributions in a semi- empirical mass model: an investigation by dividing an overdetermined system into numerous balanced subsystems
Hai-Yan Meng, Hua-Lei Wang, Zhen-Zhen Zhang, Min-Liang Liu
2022, 46(10): 104108. doi: 10.1088/1674-1137/ac7d44
We propose and test a new method of estimating the model parameters of the phenomenological Bethe-Weizsäcker mass formula. Based on the Monte Carlo sampling of a large dataset, we obtain, for the first time, a Cauchy-type parameter distribution formed by the exact solutions of linear equation systems. Using the maximum likelihood estimation, the location and scale parameters are evaluated. The estimated results are compared with those obtained by solving overdetermined systems, e.g., the solutions of the traditional least-squares method. Parameter correlations and uncertainty propagation are briefly discussed. As expected, it is also found that improvements in theoretical modeling (e.g., considering microscopic corrections) decrease the parameter and propagation uncertainties.
Geodesic equation in non-commutative gauge theory of gravity
Abdellah Touati, Slimane Zaim
2022, 46(10): 105101. doi: 10.1088/1674-1137/ac75ca
In this study, we construct a non-commutative gauge theory of the modified structure of the gravitational field using the Seiberg-Witten map and the general tetrad fields of Schwarzschild space-time to show that the non-commutative geometry removes the singularity at the origin of the black hole, thus obtaining a non-singular Schwarzschild black hole. The geodetic structure of this black hole presents new types of motion next to the event horizon within stable orbits that are not allowed by the ordinary Schwarzschild spacetime. The noncommutative periastron advance of the Mercury orbit is obtained, and with the available experimental data, we find a parameter of non-commutativity on the order of \begin{document}$10^{-25}\,\mathrm{s\cdot kg}^{-1}$\end{document}. This result shows that the new fundamental length, \begin{document}$\sqrt{\hbar \Theta }$\end{document}, is on the order of \begin{document}$10^{-31}\,\mathrm{m}$\end{document}.
Properties of proto neutron star PSR J0737-3039A
Xian-Feng Zhao, Shui-Rong Zhong, Jian-Li Huo
2022, 46(10): 105102. doi: 10.1088/1674-1137/ac76a6
Using five sets of nucleon coupling constants (DD-MEI, GL85, GL97, GM1, and NL2), we find that the radius of the PNS PSR J0737-3039A is R=15.693–18.846 km, the central baryon density is \begin{document}$\rho_{\rm c}$\end{document}=0.247–0.359 fm\begin{document}$^{-3}$\end{document}, the central energy density is \begin{document}$\varepsilon_{\rm c}$\end{document}=4.30\begin{document}$\times$\end{document}10\begin{document}$^{14}$\end{document}– 6.49\begin{document}$\times$\end{document}10\begin{document}$^{14}$\end{document} \begin{document}$ \rm g\cdot cm^{-3}$\end{document}, and the central pressure is \begin{document}$p_{\rm c}$\end{document}=3.79\begin{document}$\times$\end{document}10\begin{document}$^{34}$\end{document} – 5.85\begin{document}$\times$\end{document}10\begin{document}$^{34}$\end{document} \begin{document}$\rm dyne\cdot cm^{-2}$\end{document}. With DD-MEI, GL85, GL97, and GM1, baryon octets appear in the PNS PSR J0737-3039A. With NL2, only the baryons n, p, Λ, \begin{document}$\Sigma^{0}$\end{document}, \begin{document}$\Sigma^{-}$\end{document}, \begin{document}$\Xi^{0}$\end{document}, and \begin{document}$\Xi^{-}$\end{document} are present. Corresponding to the same baryon density, the relative densities of the same baryon in the PNS PSR J0737-3039A calculated using different nucleon coupling constants differ greatly. The central relative baryon densities of the PNS PSR J0737-3039A calculated using different nucleon coupling constants also differ greatly.
Quasinormal oscillations and late-time tail of massless scalar perturbations of a magnetized black hole in Rastall gravity
Cai-Ying Shao, Yu-Jie Tan, Cheng-Gang Shao, Kai Lin, Wei-Liang Qian
2022, 46(10): 105103. doi: 10.1088/1674-1137/ac7855
In this study, we investigate the quasinormal mode and late-time tail of charged massless scalar perturbations of a black hole in generalized Rastall gravity. The black hole metric in question is spherically symmetric, accompanied by a power-Maxwell field surrounded by a quintessence fluid. We show that the massless scalar field, when dressed up with the magnetic field, acquires an effective mass, which significantly affects the properties of the resultant quasinormal oscillations and late-time tails. Specifically, the quasinormal frequencies become distorted and might even be unstable for particular spacetime configurations. Additionally, the exponent of the usual power-law tail is modified according to the modification in the structure of the branch cut of the retarded Green's function. In particular, as the effective mass is generated dynamically owing to the presence of the magnetic field, we may consider a process through which the field is gradually removed from the spacetime configuration. In this context, while the quasinormal oscillations converge to the case of massless perturbations, we argue that the properties of resultant late-time tails do not fall back to their massless counterpart. The relevant characteristics are investigated using numerical and analytic approaches.
Tidal effects of a dark matter halo around a galactic black hole
Jiayi Liu, Songbai Chen, Jiliang Jing
2022, 46(10): 105104. doi: 10.1088/1674-1137/ac7856
We investigate tidal forces and geodesic deviation motion in the spacetime of a black hole in a galaxy with a dark matter halo. Our results show that tidal forces and geodesic deviation motion depend on the mass of the dark matter halo and the typical lengthscale of the galaxy. The effect of the typical lengthscale of the galaxy on the tidal force is opposite to that of dark matter mass. With increasing dark matter mass, the radial tidal force increases in the region far from the black hole but decreases in the region near the black hole. Furthermore, the absolute value of angular tidal force monotonously increases with the dark matter halo mass. The angular tidal force also depends on the particle energy, and the effects of dark matter become more distinct for the test particle at higher energies, which differs from the behavior observed in typical static black hole spacetimes. We also present the change in the geodesic deviation vector with dark matter halo mass and the typical lengthscale of a galaxy under two types of initial conditions.
Anisotropic stars in modified gravity: An extended gravitational decoupling approach
S. K. Maurya, B. Mishra, Saibal Ray, Riju Nag
2022, 46(10): 105105. doi: 10.1088/1674-1137/ac7d45
In this study, we conduct an investigation on decoupling gravitational sources under the framework of \begin{document}$ f(R,T) $\end{document} gravity. Basically, the complete geometric deformation technique is employed, which facilitates finding the exact solutions to the anisotropic astrophysical system smoothly without imposing any particular ansatz for the deformation function. In addition, we used 5-dimensional Euclidean spacetime in order to describe the embedding Class I spacetime in order to obtain a solvable spherical physical system. The resulting solutions are both physically interesting and viable with new possibilities for investigation. Notably, the present investigation demonstrates that the mixture of \begin{document}$ f(R,T) $\end{document} + CGD translates to a scenario beyond the pure GR realm and helps to enhance the features of the interior astrophysical aspects of compact stellar objects. To determine the physical acceptability and stability of the stellar system based on the obtained solutions, we conducted a series of physical tests that satisfied all stability criteria, including the nonsingular nature of density and pressure.
Towards a unified interpretation of the early Universe in R2-corrected dark energy model of F(R) gravity
Hua Chen, Taishi Katsuragawa, Shinya Matsuzaki
2022, 46(10): 105106. doi: 10.1088/1674-1137/ac7d46
\begin{document}$ R^2 $\end{document}-corrected dark energy (DE) models in \begin{document}$ F(R) $\end{document} gravity have been widely investigated in recent years, which not only removes the weak singularity potentially present in DE models but also provide us with a unified picture of the cosmic history, including the inflationary and DE epochs. Towards the unified interpretation of dynamical DE all over the cosmic history in the class of \begin{document}$ R^2 $\end{document}-corrected DE models, we explore the universal features of the scalaron dynamics in the radiation-dominated epoch, along with the chameleon mechanism, by keeping our eyes on the inflationary and DE epochs. We show that the scalaron evolution does not follow a surfing solution and is mostly adiabatic before big bang nucleosynthesis (BBN), even properly including the kick by the nonperturbative QCD phase transition, hence a catastrophic consequence claimed in the literature is not applied to this class of DE models. This is due to the presence of the gigantic scale hierarchy between \begin{document}$ R^2 $\end{document} correction and DE, so is the universal feature for the class of \begin{document}$ R^2 $\end{document}-corrected DE models. The prospects for the post- or onset-inflationary epoch would be pretty different from what the standard \begin{document}$ R^2 $\end{document} inflationary scenario undergoes due to the presence of the chameleon mechanism.