2022 Vol. 46, No. 11

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2022-11 Contents
2022, 46(11): 1-2.
Isotopic production cross sections of fragmentation residues produced by 18O ions on a carbon target near 260 MeV/nucleon
Xiao-Dong Xu, Ya-Zhou Sun, Shi-Tao Wang, Bo Mei, Shu-Ya Jin, Xue-Heng Zhang, Zhi-Yu Sun, Yi-Xuan Zhao, Shu-Wen Tang, Yu-Hong Yu, Duo Yan, Fang Fang, Yong-Jie Zhang, Shao-Bo Ma
2022, 46(11): 111001. doi: 10.1088/1674-1137/ac827c
The isotopic cross sections of residual nuclei produced in fragmentation reactions of 18O projectiles impinging on a carbon target at energies near 260 MeV/nucleon were measured at the HIRFL facility in Lanzhou (China). A full identification of atomic and mass numbers of fragments was achieved from the determination of their magnetic rigidity, energy loss, and time of flight. The production cross sections for a dozen of nitrogen, carbon, and boron isotopes were determined with uncertainties below 30% for most of the cases. The obtained cross sections for N and B isotopes show a rather good agreement with previous experimental data obtained with different projectile energies. The cross sections for some C isotopes seem to exhibit a dependence on the projectile energy. A comparison of the data and several theoretical model calculations are presented.
Observation of the Y(4230) and a new structure in ${\boldsymbol e^+\boldsymbol e^- \boldsymbol\rightarrow \boldsymbol K^+\boldsymbol K^-\boldsymbol J/\boldsymbol\psi} $
M. Ablikim, M. N. Achasov, P. Adlarson, M. Albrecht, R. Aliberti, A. Amoroso, M. R. An, Q. An, X. H. Bai, Y. Bai, O. Bakina, R. Baldini Ferroli, I. Balossino, Y. Ban, V. Batozskaya, D. Becker, K. Begzsuren, N. Berger, M. Bertani, D. Bettoni, F. Bianchi, J. Bloms, A. Bortone, I. Boyko, R. A. Briere, A. Brueggemann, H. Cai, X. Cai, A. Calcaterra, G. F. Cao, N. Cao, S. A. Cetin, J. F. Chang, W. L. Chang, G. Chelkov, C. Chen, G. Chen, H. S. Chen, M. L. Chen, S. J. Chen, T. Chen, X. R. Chen, X. T. Chen, Y. B. Chen, Z. J. Chen, W. S. Cheng, X. Chu, G. Cibinetto, F. Cossio, J. J. Cui, H. L. Dai, J. P. Dai, A. Dbeyssi, R. E. de Boer, D. Dedovich, Z. Y. Deng, A. Denig, I. Denysenko, M. Destefanis, F. De Mori, Y. Ding, J. Dong, L. Y. Dong, M. Y. Dong, X. Dong, S. X. Du, P. Egorov, Y. L. Fan, J. Fang, S. S. Fang, W. X. Fang, Y. Fang, R. Farinelli, L. Fava, F. Feldbauer, G. Felici, C. Q. Feng, J. H. Feng, K Fischer, M. Fritsch, C. Fritzsch, C. D. Fu, H. Gao, Y. N. Gao, Yang Gao, S. Garbolino, I. Garzia, P. T. Ge, C. Geng
2022, 46(11): 111002. doi: 10.1088/1674-1137/ac945c
The cross sections of \begin{document}$ e^+e^- \rightarrow K^+K^-J/\psi $\end{document} at center-of-mass energies from 4.127 to 4.600 GeV are measured based on 15.6 fb\begin{document}$ ^{-1} $\end{document} data collected with the BESIII detector operating at the BEPCII storage ring. Two resonant structures are observed in the line shape of the cross sections. The mass and width of the first structure are measured to be (\begin{document}$ 4225.3\pm2.3\pm21.5 $\end{document}) MeV and (\begin{document}$ 72.9\pm6.1\pm30.8 $\end{document}) MeV, respectively. They are consistent with those of the established \begin{document}$ Y(4230) $\end{document}. The second structure is observed for the first time with a statistical significance greater than 8σ, denoted as \begin{document}$ Y(4500) $\end{document}. Its mass and width are determined to be (\begin{document}$ 4484.7\pm13.3\pm24.1 $\end{document}) MeV and (\begin{document}$ 111.1\pm30.1\pm15.2 $\end{document}) MeV, respectively. The first presented uncertainties are statistical and the second ones are systematic. The product of the electronic partial width with the decay branching fraction \begin{document}$ \Gamma(Y(4230)\to e^+ e^-) \mathcal{B}(Y(4230) \to K^+ K^- J/\psi) $\end{document} is reported.
Emergence of mass in the gauge sector of QCD
J. Papavassiliou
2022, 46(11): 112001. doi: 10.1088/1674-1137/ac84ca
It is currently widely accepted that gluons, while massless at the level of the fundamental QCD Lagrangian, acquire an effective mass through the non-Abelian implementation of the classic Schwinger mechanism. The key dynamical ingredient that triggers the onset of this mechanism is the formation of composite massless poles inside the fundamental vertices of the theory. These poles enter the evolution equation of the gluon propagator and nontrivially affect the way the Slavnov-Taylor identities of the vertices are resolved, inducing a smoking-gun displacement in the corresponding Ward identities. In this article, we present a comprehensive review of the pivotal concepts associated with this dynamical scenario, emphasizing the synergy between functional methods and lattice simulations and highlighting recent advances that corroborate the action of the Schwinger mechanism in QCD.
Classify the Higgs decays with the PFN and ParticleNet at electron–positron colliders
Gang Li, Libo Liao, Xinchou Lou, Peixun Shen, Weimin Song, Shudong Wang, Zhaoling Zhang
2022, 46(11): 113001. doi: 10.1088/1674-1137/ac7f21
Various Higgs factories are proposed to study the Higgs boson precisely and systematically in a model- independent way. In this study, the Particle Flow Network and ParticleNet techniques are used to classify the Higgs decays into multicategories, and the ultimate goal is to realize an "end-to-end" analysis. A Monte Carlo simulation study is performed to demonstrate the feasibility, and the performance looks rather promising. This result could be the basis of a "one-stop" analysis to measure all the branching fractions of the Higgs decays simultaneously.
Measurement of integrated luminosities at BESIII for data samples at center-of-mass energies between 4.0 and 4.6 GeV
M. Ablikim, M. N. Achasov, P. Adlarson, S. Ahmed, M. Albrecht, R. Aliberti, A. Amoroso, M. R. An, Q. An, X. H. Bai, Y. Bai, O. Bakina, R. Baldini Ferroli, I. Balossino, Y. Ban, V. Batozskaya, D. Becker, K. Begzsuren, N. Berger, M. Bertani, D. Bettoni, F. Bianchi, J. Bloms, A. Bortone, I. Boyko, R. A. Briere, H. Cai, X. Cai, A. Calcaterra, G. F. Cao, N. Cao, S. A. Cetin, J. F. Chang, W. L. Chang, G. Chelkov, C. Chen, G. Chen, H. S. Chen, M. L. Chen, S. J. Chen, T. Chen, X. R. Chen, X. T. Chen, Y. B. Chen, Z. J. Chen, W. S. Cheng, G. Cibinetto, F. Cossio, J. J. Cui, X. F. Cui, H. L. Dai, J. P. Dai, X. C. Dai, A. Dbeyssi, R. E. de Boer, D. Dedovich, Z. Y. Deng, A. Denig, I. Denysenko, M. Destefanis, F. De Mori, Y. Ding, C. Dong, J. Dong, L. Y. Dong, M. Y. Dong, X. Dong, S. X. Du, P. Egorov, Y. L. Fan, J. Fang, S. S. Fang, Y. Fang, R. Farinelli, L. Fava, F. Feldbauer, G. Felici, C. Q. Feng, J. H. Feng, M. Fritsch, C. D. Fu, Y. N. Gao, Yang Gao, I. Garzia, P. T. Ge, C. Geng, E. M. Gersabeck, A Gilman, K. Goetzen,
2022, 46(11): 113002. doi: 10.1088/1674-1137/ac80b4
The integrated luminosities of data samples collected in the BESIII experiment in 2016–2017 at center-of-mass energies between 4.19 and 4.28 GeV are measured with a precision better than 1% by analyzing large-angle Bhabha scattering events. The integrated luminosities of old datasets collected in 2010–2014 are updated by considering corrections related to detector performance, offsetting the effect of newly discovered readout errors in the electromagnetic calorimeter, which can haphazardly occur.
Luminosities and energies of e+e collision data taken between ${\sqrt{\boldsymbol s}}$=4.61 GeV and 4.95 GeV at BESIII
M. Ablikim, M. N. Achasov, P. Adlarson, M. Albrecht, R. Aliberti, A. Amoroso, M. R. An, Q. An, X. H. Bai, Y. Bai, O. Bakina, Ferroli R. Baldini, I. Balossino, Y. Ban, V. Batozskaya, D. Becker, K. Begzsuren, N. Berger, M. Bertani, D. Bettoni, F. Bianchi, J. Bloms, A. Bortone, I. Boyko, R. A. Briere, A. Brueggemann, H. Cai, X. Cai, A. Calcaterra, G. F. Cao, N. Cao, S. A. Cetin, J. F. Chang, W. L. Chang, G. Chelkov, C. Chen, Chao Chen, G. Chen, H. S. Chen, M. L. Chen, S. J. Chen, S. M. Chen, T. Chen, X. R. Chen, X. T. Chen, Y. B. Chen, Z. J. Chen, W. S. Cheng, X. Chu, G. Cibinetto, F. Cossio, J. J. Cui, H. L. Dai, J. P. Dai, A. Dbeyssi, Boer R. E. de, D. Dedovich, Z. Y. Deng, A. Denig, I. Denysenko, M. Destefanis, Mori F. De, Y. Ding, J. Dong, L. Y. Dong, M. Y. Dong, X. Dong, S. X. Du, P. Egorov, Y. L. Fan, J. Fang, S. S. Fang, W. X. Fang, Y. Fang, R. Farinelli, L. Fava, F. Feldbauer, G. Felici, C. Q. Feng, J. H. Feng, K Fischer, M. Fritsch, C. Fritzsch, C. D. Fu, H. Gao, Y. N. Gao, Yang Gao, S. Garbolino, I. Ga
2022, 46(11): 113003. doi: 10.1088/1674-1137/ac84cc
From December 2019 to June 2021, the BESIII experiment collected approximately 5.85 fb−1 of data at center-of-mass energies between 4.61 and 4.95 GeV. This is the highest collision energy BEPCII has reached to date. The accumulated \begin{document}$e^+e^-$\end{document} annihilation data samples are useful for studying charmonium(-like) states and charmed-hadron decays. By adopting a novel method of analyzing the production of \begin{document}$\Lambda_{c}^{+}\bar{\Lambda}_{c}^{-}$\end{document} pairs in \begin{document}$e^+e^-$\end{document} annihilation, the center-of-mass energies are measured with a precision of \begin{document}$\sim$\end{document}0.6 MeV. Integrated luminosities are measured with a precision of better than 1% by analyzing the events of large-angle Bhabha scattering. These measurements provide important inputs to analyses based on these data samples.
Direct CP violation of three body decay processes from the resonance effect
Gang Lü, Yan-Lin Zhao, Liang-Chen Liu, Xin-Heng Guo
2022, 46(11): 113101. doi: 10.1088/1674-1137/ac80ef
The physical state of \begin{document}$ \rho-\omega-\phi $\end{document} mesons can be mixed using the unitary matrix. The decay processes \begin{document}$ \omega \rightarrow \pi^{+}\pi^{-} $\end{document} and \begin{document}$ \phi \rightarrow \pi^{+}\pi^{-} $\end{document} originate from isospin symmetry breaking. The \begin{document}$ \rho-\omega $\end{document}, \begin{document}$ \rho-\phi $\end{document}, and \begin{document}$ \omega-\phi $\end{document} interferences lead to a resonance contribution to produce strong phases. \begin{document}$ CP $\end{document} violation is considered from isospin symmetry breaking due to the new strong phase of the first order. \begin{document}$ CP $\end{document} violation can be enhanced greatly for the decay process \begin{document}$ B^{0}\rightarrow \pi^+\pi^{-}\eta^{(')} $\end{document} when the invariant masses of \begin{document}$ \pi^+\pi^{-} $\end{document} pairs are in the area around the \begin{document}$ \omega $\end{document} resonance range and \begin{document}$ \phi $\end{document} resonance range in perturbative QCD. We also discuss the possibility of searching for the predicted \begin{document}$ CP $\end{document} violation at the LHC.
An estimate of dibaryon production in the process of ${\boldsymbol p{{\bar{\boldsymbol p}}}\to\boldsymbol d^*({\bf 2380})+{\bar{\boldsymbol p}}{\bar{\boldsymbol n}} }$ at ${ {\bar{{\bf{P}}}}} $anda facility
Yubing Dong, Pengnian Shen
2022, 46(11): 113102. doi: 10.1088/1674-1137/ac80f0
Although \begin{document}$ d^*(2380) $\end{document} was first observed by WASA@COSY, its existence has yet to be further confirmed in different types of processes at other facilities. In this work, the possible production of the single dibaryon state \begin{document}$ d^*(2380) $\end{document} in the process of \begin{document}$ p{\bar{p}}\to d^*(2380){\bar{p}}{\bar{n}} $\end{document} in a future experiment at the \begin{document}$ {\bar{{\rm{P}}}} $\end{document}anda facility is estimated. Following the method used in our previous study (Chin. Phys. C 46, 023105), a phenomenological Lagrangian approach is employed to study the single \begin{document}$ {d^*} $\end{document} production. Based on the conclusions obtained by the non-relativistic constituent quark model, the cross section of the \begin{document}$ p{\bar{p}}\to d^*(2380){\bar{p}}{\bar{n}} $\end{document} reaction via the \begin{document}$ \Delta{\bar{\Delta}} $\end{document} intermediate state is estimated, which is in the order of \begin{document}$ nb $\end{document}. It is shown that the dominant contribution comes from the diagram with the \begin{document}$ {\bar{\Delta}}{\bar{\Delta}}\to {\bar{p}}{\bar{n}} $\end{document} subprocess. However, it is difficult to measure owing to the large background. Further, although the cross section of the diagram with the \begin{document}$ {\bar{d^*}}\to {\bar{p}}{\bar{n}} $\end{document} subprocess is small, i.e., only approximately \begin{document}$ 3\%\sim 4\% $\end{document} of the total cross section or even smaller, the corresponding number of events is still sufficiently large and can be measured at \begin{document}$ {\bar{{\rm{P}}}} $\end{document}anda because the outgoing \begin{document}$ {\bar{p}} $\end{document} and \begin{document}$ {\bar{n}} $\end{document} come from the same source \begin{document}$ {\bar{d^*}} $\end{document}.
Entropic destruction of heavy quarkonium in a rotating hot and dense medium from holography
Ping-ping Wu, Zi-qiang Zhang, Xiangrong Zhu
2022, 46(11): 113103. doi: 10.1088/1674-1137/ac814e
Previous studies have indicated that the peak of the quarkonium entropy at the deconfinement transition can be related to the entropic force, which would induce the dissociation of heavy quarkonium. In this study, we investigated the entropic force in a rotating hot and dense medium using AdS/CFT correspondence. It was found that the inclusion of angular velocity increases the entropic force, thus enhancing quarkonium dissociation, while chemical potential has the same effect. The results imply that the quarkonium dissociates easier in rotating medium compared with the static case.
Mono-γ production of a dark vector at future e+e colliders
Kai Ma
2022, 46(11): 113104. doi: 10.1088/1674-1137/ac827b
The associated production of a dark particle and photon, represented as a mono-γ event, is a promising channel to probe particle content and dynamics in the dark sector. In this study, we investigate the properties of the mono-γ production of vector dark matter at future \begin{document}$ e^+e^- $\end{document} colliders. Photon-like and Pauli operators as well as triple gauge boson interactions involving dark matter are considered in the framework of effective field theory. We show that, in comparison with the Pauli operator, the triple gauge boson couplings are significantly more interesting in high energy colliders. Beam polarization effects are also analyzed, and we show that the experimental sensitivities cannot be significantly enhanced because of the smaller luminosity.
Probing top-quark operators with precision electroweak measurements
Yiming Liu, Yuhao Wang, Cen Zhang, Lei Zhang, Jiayin Gu
2022, 46(11): 113105. doi: 10.1088/1674-1137/ac82e1
In the standard model effective field theory, operators involving the top quark are generally difficult to probe and can generate sizable loop contributions to electroweak precision observables measured by past and future lepton colliders. Could the high precision of electroweak measurements compensate for loop suppression and provide competitive reaches on these operators? Would the inclusion of these contributions introduce too many additional parameters for a meaningful global electroweak analysis to be performed? In this paper, we perform a detailed phenomenological study to address these two important questions. Focusing on eight dimension-6 operators that generate anomalous couplings between electroweak gauge bosons and third-generation quarks, we calculate their one loop contributions to \begin{document}$ e^+e^- \to f\bar{f} $\end{document} processes, both on and off the Z-pole, and the \begin{document}$ e^-e^+ \to WW $\end{document} process. A global analysis is performed with these eight operators and those that contribute to the above processes at tree level using measurements at the LEP, SLC, and several low energy experiments. We find that although current electroweak precision measurements are sensitive to the one-loop effects of top-quark operators, it is difficult to separate them from the operators that contribute at tree level, making a global analysis rather challenging. Under further assumptions (for instance, new physics contributes to only third generation quark operators and the S and T parameters), competitive reaches may be obtained in a global fit. Another important finding of our study is that the two operators that generate the dipole interactions of the bottom quark have a significant impact on the Z-pole measurements and should not be omitted. We also discuss the implications of the recently reported W-boson mass measurement at the CDF for our results. Finally, we estimate the reaches of future lepton colliders in probing top-quark operators with precision electroweak measurements.
Magnetic dipole moments of ${{\boldsymbol{B_{(\boldsymbol s)}^{(\bf *)} B_{(\boldsymbol s)}^{(\bf *)}}}}$ states
Ulaş Özdem
2022, 46(11): 113106. doi: 10.1088/1674-1137/ac8653
We systematically study the magnetic dipole moments of multiquark states. In this study, the magnetic dipole moments of possible \begin{document}$ B^- B^{*-} $\end{document}, \begin{document}$ B^0 B^{*-} $\end{document}, \begin{document}$ B^- B^{*0} $\end{document}, \begin{document}$ B^0 B^{*0} $\end{document}, \begin{document}$ B_s^0 B^{*-} $\end{document}, \begin{document}$ B^- B_s^{*0} $\end{document}, \begin{document}$ B_s^{0} B^{*0} $\end{document}, \begin{document}$ B^0 B_s^{*0} $\end{document}, and \begin{document}$ B^0_s B_s^{*0} $\end{document} states are extracted using light-cone sum rules. We explore the magnetic dipole moments of these states in a molecular picture with spin-parity \begin{document}$ J^P = 1^+ $\end{document}. The magnetic dipole moments of hadrons include useful information on the distributions of internal charge and magnetization, which can be used to understand their geometrical shapes and quark-gluon organization. The results of the present study along with the spectroscopic parameters may help future theoretical and experimental research on the characteristics of doubly-bottom tetraquark states.
Λb → Λc form factors from QCD light-cone sum rules
Yan Miao, Hui Deng, Ke-Sheng Huang, Jing Gao, Yue-Long Shen
2022, 46(11): 113107. doi: 10.1088/1674-1137/ac8652
In this study, we calculate the transition form factors of \begin{document}$ \Lambda_b $\end{document} decaying into \begin{document}$ \Lambda_c $\end{document} within the framework of light-cone sum rules with the distribution amplitudes (DAs) of the \begin{document}$ \Lambda_b $\end{document}-baryon. In the hadronic representation of the correlation function, we isolate both the \begin{document}$ \Lambda_c $\end{document} and \begin{document}$ \Lambda_c^* $\end{document} states so that the \begin{document}$ \Lambda_b \rightarrow \Lambda_c $\end{document}form factors can be obtained without ambiguity. We investigate the P-type and A-type currents to interpolate light baryons for comparison because the interpolation current for the baryon state is not unique. We also employ three parametrization models for the DAs of \begin{document}$ \Lambda_b $\end{document} in the numerical calculation. We present the numerical predictions for the \begin{document}$ \Lambda_b \rightarrow \Lambda_c $\end{document} form factors and branching fractions, averaged forward-backward asymmetry, averaged final hadron polarization, and averaged lepton polarization of the \begin{document}$ \Lambda_b \to \Lambda_c \ell\mu $\end{document} decays, as well as the ratio of the branching ratios \begin{document}$ R_{\Lambda_c} $\end{document}. The predicted \begin{document}$ R_{\Lambda_c} $\end{document} is consistent with LHCb data.
Determination of the half-life of 184gRe and the isomeric ratio of 184m, gRe induced by D-T neutrons
Changlin Lan, Yuting Wei, Jiahao Wang, Xianlin Yang, Gong Jiang, Yujie Ge, Chao Xu, Li Feng, Xiaojun Li
2022, 46(11): 114001. doi: 10.1088/1674-1137/ac7f88
The isomeric ratio of 184m, gRe and the half-life of 184gRe were measured in the 185Re (n, 2n) 184Re reaction at 14.8 MeV, and the uncertainty was discussed in detail. The measurements were performed using the activation method implemented for a rhenium sample using the K-400 neutron generator at the Chinese Academy of Engineering Physics (CAEP). Isomeric state and ground state nuclei of 184Re were identified by their γ-ray spectra. To eliminate the effect of the γ-ray emitted from the isomer on the counting of the ground state characteristic peaks, the isomeric ratio of 184m, gRe was calculated to be 0.29 ± 0.11 according to the neutron activation cross-section formula. This result is consistent with previous data within the uncertainty and can be used to determine parameters that characterize the dependence of the level density on the excitation energy and angular momentum. Through exponential function fitting and a detailed discussion of the uncertainty evaluation, the half-life of 184gRe was determined as 35.43 ± 0.16 d, which is consistent with the currently recommended value; however, the uncertainty assessment of the latter was barely documented. In addition, this study indicates that the half-life of the ground state can be obtained by eliminating the contamination of γ-rays emitted from the isomer, which provides the possibility of determining the half-lives of nuclides containing isomers.
Emission of high-energy alpha particles in nuclear reactions of 48Ca and 56Fe ions on 181Ta and 238U targets
Yu. E. Penionzhkevich, V. V. Samarin, S. M. Lukyanov, V. A. Maslov, M. A. Naumenko
2022, 46(11): 114002. doi: 10.1088/1674-1137/ac8227
The results of experiments on measuring the energy spectra of alpha particles in reactions with heavy ions are presented. The measurements were performed using the high-resolution magnetic analyzer MAVR with beams of 48Ca (280 MeV) and 56Fe (320 and 400 MeV) on 181Ta and 238U targets at an angle of 0°. A strong dependence of the double differential cross sections for production of alpha particles on the atomic number of the target nucleus was observed, which indicates that fast alpha particles are mainly emitted from the target nucleus; this conclusion was also confirmed by calculations within the time-dependent Schrödinger equation approach. An analysis of the obtained experimental data was carried out within the model of moving sources modified to consider the kinematic limits for two-body and three-body exit channels.
Number of states with given spin I and isospin T for n fermions in a j orbit
X. Yin, Y. M. Zhao
2022, 46(11): 114101. doi: 10.1088/1674-1137/ac7eb3
In this study, we investigate formulas of the number of states with a given total spin I and isospin T for n nucleons in a single-j shell denoted by \begin{document}$ D_{IT} (j, n) $\end{document}. Talmi's recursion formulas for the number of states with a given z-axis projection of total spin are generalized by further considering the isospin couplings and are applied to derive explicit formulas of \begin{document}$ D_{IT} (j, n) $\end{document}.
Investigating color screening in proton-nucleus collisions with complex potentials
Liuyuan Wen, Xiaojian Du, Shuzhe Shi, Baoyi Chen
2022, 46(11): 114102. doi: 10.1088/1674-1137/ac7fe6
Color screening and parton inelastic scattering modify the heavy-quark antiquark potential in mediums consisting of particles from quantum chromodynamics (QCD), leading to the suppression of quarkonium production in relativistic heavy-ion collisions. Owing to the small charm/anti-charm (\begin{document}$ c\bar{c} $\end{document}) pair production number in proton-nucleus (pA) collisions, the correlation between different \begin{document}$ c\bar{c} $\end{document} pairs is negligible, which makes the Schrödinger equation viable for tracking the evolution of only one \begin{document}$ c\bar{c} $\end{document} pair. We employ the time-dependent Schrödinger equation with an in-medium \begin{document}$ c\bar{c} $\end{document} potential to study the evolution of charmonium wave functions in a hydrodynamic-like QCD medium produced in pA collisions. We explore different parametrizations of real and imaginary parts of the \begin{document}$ c\bar{c} $\end{document} potential and calculate the nuclear modification factors (\begin{document}$R_{pA}$\end{document}) of \begin{document}$ J/\psi $\end{document} and \begin{document}$ \psi(2S) $\end{document} in \begin{document}$ \sqrt{s_{NN}}=5.02 $\end{document} TeV energy p-Pb collisions at the Large Hadron Collider (LHC). Comparing strong and weak screening scenarios with experimental data in this approach, we arrive at the conclusion that color screening is weak at temperatures close to the deconfined phase transition. Moreover, the imaginary part of the potential is crucial in describing the experimental data, which is consistent with widely studied semi-classical approaches, where dissociation rates are essential.
Systematic study on α-decay half-lives of uranium isotopes with a screened electrostatic barrier
Yang-Yang Xu, De-Xing Zhu, You-Tian Zou, Xi-Jun Wu, Biao He, Xiao-Hua Li
2022, 46(11): 114103. doi: 10.1088/1674-1137/ac7fe8
In the present work, we systematically study the α-decay half-lives of uranium (Z=92) isotopes based on the Gamow model with a screened electrostatic barrier. There are only two adjustable parameters in our model i.e. the parameter g and the screening parameter t in the Hulthen potential for considering the screened electrostatic effect of the Coulomb potential. The calculated results are in good agreement with experimental data, and the corresponding root-mean-square (rms) deviations of uranium isotopes with α transition orbital angular momentum l=0 and l=2 are 0.141 and 0.340, respectively. Moreover, we extend this model to predict α-decay half-lives of uranium isotopes whose α decay is energetically allowed or observed but not yet quantified in NUBASE2020. For comparison, the modified Hatsukawa formula (XLZ), the unified Royer formula (DZR), the universal decay law (UDL) and the Viola–Seaborg–Sobiczewski formula (VSS) are also used. The predictions are basically consistent with each other. Meanwhile, the results also indicate that N=126 shell closure is still robust at Z=92 and the spectroscopic factor \begin{document}$ S_{\alpha} $\end{document} is almost the same for uranium isotopes with the same l.
Roles of tensor and isoscalar pairing interactions in β-decay calculations for possible r-process waiting point nuclei with N ~ 82 and 126
C. L. Bai, D. L. Fang, H. Q. Zhang
2022, 46(11): 114104. doi: 10.1088/1674-1137/ac80ee
In this study, we adopt the self-consistent Hartree-Fock-Bogoliubov (HFB) theory with the proton-neutron quasi-particle random phase approximation (pnQRPA) based on the Skyrme force for calculation of the β decay half-lives for nuclei with N ~ 82 and 126 on possible r-process paths. In the calculations, the Skyrme interaction (e.g., SKO') is adopted, and the tensor interaction is added self-consistently in both HFB and QRPA calculations. We systematically study how the half-life is changed by varying the strength of the triplet-even (TE) and triplet-odd (TO) components as well as the IS pairing. We find that a variation in strength of the IS pairing of approximately 20% does not produce a substantial effect on β-decay rates with or without the tensor force, while a strength variation of the TO tensor force considerably affects the change in the β-decay half-lives for the very neutron rich N ~ 82 and 126 isotonic chains. In addition, with the inclusion of the tensor force, the GT decay becomes dominant for very neutron-rich nuclei.
Nuclear liquid-gas phase transition within a Brueckner-Hartree-Fock approach
Jing Zhang, Hong-Ming Liu, Zeng-Hua Li, G. F. Burgio, H.-J. Schulze
2022, 46(11): 114105. doi: 10.1088/1674-1137/ac82e2
The critical parameters of the liquid-gas phase transition of symmetric nuclear matter are computed using the Brueckner-Hartree-Fock method at finite temperature by employing different realistic nucleon-nucleon potentials. Temperature effects on single-particle potentials, defect functions, and three-body forces are discussed in detail. Results obtained from the full procedure and frozen-correlations approximation are compared. We find critical temperatures of approximately 14 to 19 MeV and critical densities in the range of \begin{document}$ 0.05 $\end{document} to \begin{document}$ 0.08{\;\mathrm{fm}^{-3}} $\end{document}, depending on the interactions employed.
Dibaryon resonances and short-range NN interaction
V.I. Kukulin, V.N. Pomerantsev, O.A. Rubtsova, M.N. Platonova, I.T. Obukhovsky
2022, 46(11): 114106. doi: 10.1088/1674-1137/ac82e3
The dibaryon concept for nuclear force is presented, assuming that the attraction between nucleons at medium distances is mainly due to the s-channel exchange of an intermediate six-quark (dibaryon) state. To construct the respective NN interaction model, a microscopic six-quark description of the NN system is used, in which symmetry aspects play a special role. It is shown that the NN interaction in all important partial waves can be described by the superposition of long-range t-channel one-pion exchange and s-channel exchange by an intermediate dibaryon. The model developed in this study provides a good description of both elastic phase shifts and inelasticities of NN scattering in all S, P, D, and F partial waves at energies from zero to 600–800 MeV and even higher. The parameters of the intermediate six-quark states, corresponding to the best fit of NN scattering data, are found to be consistent with the parameters of the known dibaryon resonances in those NN partial configurations, where their existence has been experimentally confirmed. Predictions for new dibaryon states are given as well.
Neutron-induced nuclear recoil background in the PandaX-4T experiment
Zhou Huang, Guofang Shen, Qiuhong Wang, Abdusalam Abdukerim, Zihao Bo, Wei Chen, Xun Chen, Yunhua Chen, Chen Cheng, Yunshan Cheng, Xiangyi Cui, Yingjie Fan, Deqing Fang, Changbo Fu, Mengting Fu, Lisheng Geng, Karl Giboni, Linhui Gu, Xuyuan Guo, Chencheng Han, Ke Han, Changda He, Jinrong He, Di Huang, Yanlin Huang, Ruquan Hou, Xiangdong Ji, Yonglin Ju, Chenxiang Li, Mingchuan Li, Shu Li, Shuaijie Li, Qing Lin, Jianglai Liu, Xiaoying Lu, Lingyin Luo, Wenbo Ma, Yugang Ma, Yajun Mao, Yue Meng, Xuyang Ning, Ningchun Qi, Zhicheng Qian, Xiangxiang Ren, Nasir Shaheed, Changsong Shang, Lin Si, Wenliang Sun, Andi Tan, Yi Tao, Anqing Wang, Meng Wang, Shaobo Wang, Siguang Wang, Wei Wang, Xiuli Wang, Zhou Wang, Mengmeng Wu, Weihao Wu, Jingkai Xia, Mengjiao Xiao, Xiang Xiao, Pengwei Xie, Binbin Yan, Xiyu Yan, Jijun Yang, Yong Yang, Chunxu Yu, Jumin Yuan, Ying Yuan, Dan Zhang, Minzhen Zhang, Peng Zhang, Tao Zhang, Li Zhao, Qibin Zheng, Jifang Zhou, Ning Zhou, Xiaopeng Zhou, Yong Zhou, (PandaX Collaboration)
2022, 46(11): 115001. doi: 10.1088/1674-1137/ac8539
Neutron-induced nuclear recoil background is critical to dark matter searches in the PandaX-4T liquid xenon experiment. In this study, we investigate the features of neutron background in liquid xenon and evaluate its contribution in single scattering nuclear recoil events using three methods. The first method is fully based on Monte Carlo simulations. The last two are data-driven methods that also use multiple scattering signals and high energy signals in the data. In the PandaX-4T commissioning data with an exposure of 0.63 tonne-year, all these methods give a consistent result, i.e., there are \begin{document}$ 1.15\pm0.57 $\end{document} neutron-induced backgrounds in the dark matter signal region within an approximated nuclear recoil energy window between 5 and 100 keV.
Static spherically symmetric wormholes in $ {\boldsymbol f(\boldsymbol Q,T)} $ gravity
Moreshwar Tayde, Zinnat Hassan, P.K. Sahoo, Sashideep Gutti
2022, 46(11): 115101. doi: 10.1088/1674-1137/ac7f22
In this study, we obtain wormhole solutions in the recently proposed extension of symmetric teleparallel gravity, known as \begin{document}$ f(Q,T) $\end{document} gravity. Here, the gravitational Lagrangian L is defined by an arbitrary function f of Q and T, where Q is a non-metricity scalar, and T is the trace of the energy-momentum tensor. In this study, we obtain field equations for a static spherically symmetric wormhole metric in the context of general \begin{document}$ f(Q,T) $\end{document} gravity. We study the wormhole solutions using (i) a linear equation of state and (ii) an anisotropy relation. We adopt two different forms of \begin{document}$ f(Q,T) $\end{document}, (a) linear \begin{document}$ f(Q,T)=\alpha Q+\beta T $\end{document} and (b) non-linear \begin{document}$ f(Q,T)=Q+\lambda Q^2+\eta T $\end{document}, to investigate these solutions. We investigate various energy conditions to search for preservation and violation among the obtained solutions and find that the null energy condition is violated in both cases of our assumed forms of \begin{document}$ f(Q,T) $\end{document}. Finally, we perform a stability analysis using the Tolman-Oppenheimer-Volkov equation.
QED effects on phase transition and Ruppeiner geometry of Euler-Heisenberg-AdS black holes
Xu Ye, Zi-Qing Chen, Ming-Da Li, Shao-Wen Wei
2022, 46(11): 115102. doi: 10.1088/1674-1137/ac814d
Considering the quantum electrodynamics (QED) effect, we study the phase transition and Ruppeiner geometry of Euler-Heisenberg anti-de Sitter black holes in the extended phase space. For negative and small positive QED parameters, we observe a small/large black hole phase transition and reentrant phase transition, respectively, whereas a large positive value of the QED parameter ruins the phase transition. Phase diagrams for each case are explicitly shown. Then, we construct the Ruppeiner geometry in thermodynamic parameter space. Different features of the corresponding scalar curvature are shown for both the small/large black hole phase transition and reentrant phase transition cases. Of particular interest is the additional region of positive scalar curvature, indicating a dominant repulsive interaction among black hole microstructures, for the black hole with a small positive QED parameter. Furthermore, universal critical phenomena are observed for the scalar curvature of Ruppeiner geometry. These results indicate that the QED parameter has a crucial influence on the black hole phase transition and microstructure.
Charged quark stars in f(R,T) gravity
Juan M. Z. Pretel, Takol Tangphati, Ayan Banerjee, Anirudh Pradhan
2022, 46(11): 115103. doi: 10.1088/1674-1137/ac84cb
Recent advances in nuclear theory and new astrophysical observations have led to the need for specific theoretical models applicable to dense-matter physics phenomena. Quantum chromodynamics (QCD) predicts the existence of non-nucleonic degrees of freedom at high densities in neutron-star matter, such as quark matter. Within a confining quark matter model, which consists of homogeneous, neutral 3-flavor interacting quark matter with \begin{document}$ \mathcal{O}(m_s^4) $\end{document} corrections, we examine the structure of compact stars composed of a charged perfect fluid in the context of \begin{document}$ f(R,T) $\end{document} gravity. The system of differential equations describing the structure of charged compact stars has been derived and numerically solved for a gravity model with \begin{document}$ f(R,T)= R+ 2\beta T $\end{document}. For simplicity, we assumed that the charge density is proportional to the energy density, namely, \begin{document}$ \rho_{\rm ch} = \alpha \rho $\end{document}. It is demonstrated that the matter-geometry coupling constant β and charge parameter α affect the total gravitational mass and the radius of the star.