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Scalar field in massive BTZ black hole and entanglement entropy
Yu-Ting Zhou, Xiao-Mei Kuang
Published: , doi: 10.1088/1674-1137/44/1/015102
In this paper, we investigate the quantum scalar fields in a massive BTZ black hole background. We study the entropy of the system by evaluating the entanglement entropy using a discretized approach. Specifically, we fit the results with a log -modified formula of the black hole entropy, which is introduced by quantum correction. The coefficients of leading and sub-leading terms affected by the mass of graviton are numerically analyzed.
Polarization in ${{ \Xi_c^0}}$ decays
Tong-Zhu Han, Rong-Gang Ping, Tao Luo, Guang-Zhi Xu
Published: , doi: 10.1088/1674-1137/44/1/013002
Measurements of decay asymmetry parameters of charmed baryons, e.g., $ \Xi_c$, provide more data to test the W-emission and W-exchange mechanisms controlled by strong and weak interactions. Taking advantage of the spin polarization in charmed baryon decays, we investigate the possibility to measure weak decay asymmetry parameters in the $ e^{+}e^{-}\to \Xi_c^0\bar\Xi_c^0$ process. We analyze the transverse polarization spontaneously produced in this process and the spin transfer in the subsequent $ \Xi_c$ decays. The sensitivity to measure the asymmetry parameters is estimated for the decay $ \Xi_c\to\Xi \pi$.
Deformed dispersion relation constraint with hydrogen atom 1S-2S transition
Jin Pu, Guo-Ping Li, Qing-Quan Jiang, Xiao-Tao Zu
Published: , doi: 10.1088/1674-1137/44/1/014001
We use the latest results of the ultra-high accuracy 1S-2S transition experiments in the hydrogen atom to constrain the forms of the deformed dispersion relation in the non-relativistic limit. For the leading correction of the non-relativistic limit, the experiment sets a limit at an order of magnitude for the desired Planck-scale level, thereby providing another example of the Planck-scale sensitivity in the study of the dispersion relation in controlled laboratory experiments. For the next-to-leading term, the bound is two orders of magnitude away from the Planck scale, however it still amounts to the best limit, in contrast to the previously obtained bound in the non-relativistic limit from the cold-atom-recoil experiments.
Measurements of decay branching fractions of ${{H \to b\bar b/c\bar c/gg}}$ in associated ${{(e^ + e^ - /\mu ^ +\mu ^- )H}}$ production at the CEPC
Yu Bai, Chun-Hui Chen, Ya-Quan Fang, Gang Li, Man-Qi Ruan, Jing-Yuan Shi, Bo Wang, Pan-Yu Kong, Bo-Yang Lan, Zhan-Feng Liu
Published: , doi: 10.1088/1674-1137/44/1/013001
The high-precision measurement of Higgs boson properties is one of the primary goals of the Circular Electron Positron Collider (CEPC). The measurements of $H \to b\bar b/c\bar c/gg$ decay branching fraction in the CEPC experiment is presented, considering a scenario of analysing 5000 fb-1 e+e- collision data with the center-of-mass energy of 250 GeV. In this study the Higgs bosons are produced in association with a pair of leptons, dominantly mediated by the ZH production process. The statistical uncertainty of the signal cross section is estimated to be about 1% in the $H \to b\bar b$ final state, and approximately 5%-10% in the $H \to c\bar c/gg$ final states. In addition, the main sources of the systematic uncertainties and their impacts to the measurements of branching fractions are discussed. This study demonstrates the potential of precise measurement of the hadronic final states of the Higgs boson decay at the CEPC, and will provide key information to understand the Yukawa couplings between the Higgs boson and quarks, which are predicted to be the origin of quarks’ masses in the standard model.
Microscopic study of electromagnetic properties and band spectra of neutron deficient 133,135,137Sm
Rakesh K. Pandit, R.K. Bhat, Rani Devi, S.K. Khosa, G.H. Bhat, J.A. Sheikh
Published: , doi: 10.1088/1674-1137/43/12/124108
A microscopic high spin study of neutron deficient and normally deformed 133,135,137Sm have been carried out in projected shell model framework. The theoretical results have been obtained for the spins, parities and energy values of yrast and excited bands. Besides this, the band spectra, band head energies, moment of inertia and electromagnetic transition strengths are also predicted in these isotopes. The calculations successfully give a deeper understanding of the mechanism of the formation of yrast and excited bands from the single and multi-quasi particle configurations. The results on moment of inertia predict an alignment of a pair of protons in the proton (1h11/2)2 orbitals in the yrast ground state bands of 133-137Sm due to the crossing of one quasiparticle bands by multi-quasiparticle bands at higher spins. The discussion in the present work is based on the deformed single particle scheme. Any future experimental confirmation or refutation of our predictions will be a valuable information which can help to understand the deformed single particle structure in these odd mass neutron deficient 133-137Sm.
Measurements of differential and angle-integrated cross sections for the 10B(n, α)7Li reaction in the neutron energy range from 1.0 eV to 2.5 MeV
Haoyu Jiang, Wei Jiang, Huaiyong Bai, Zengqi Cui, Guohui Zhang, Ruirui Fan, Han Yi, Changjun Ning, Liang Zhou, Jingyu Tang, Qi An, Jie Bao, Yu Bao, Ping Cao, Haolei Chen, Qiping Chen, Yonghao Chen, Yukai Chen, Zhen Chen, Changqing Feng, Keqing Gao, Minhao Gu, Changcai Han, Zijie Han, Guozhu He, Yongcheng He, Yang Hong, Hanxiong Huang, Weiling Huang, Xiru Huang, Xiaolu Ji, Xuyang Ji, Zhijie Jiang, Hantao Jing, Ling Kang, Mingtao Kang, Bo Li, Chao Li, Jiawen Li, Lun Li, Qiang Li, Xiao Li, Yang Li, Rong Liu, Shubin Liu, Xingyan Liu, Guangyuan Luan, Qili Mu, Binbin Qi, Jie Ren, Zhizhou Ren, Xichao Ruan, Zhaohui Song, Yingpeng Song, Hong Sun, Kang Sun, Xiaoyang Sun, Zhijia Sun, Zhixin Tan, Hongqing Tang, Xinyi Tang, Binbin Tian, Lijiao Wang, Pengcheng Wang, Qi Wang, Taofeng Wang, Zhaohui Wang, Jie Wen, Zhongwei Wen, Qingbiao Wu, Xiaoguang Wu, Xuan Wu, Likun Xie, Yiwei Yang, Li Yu, Tao Yu, Yongji Yu, Linhao Zhang, Qiwei Zhang, Xianpeng Zhang, Yuliang Zhang, Zhiyong Zhang, Yubin Zhao, Luping Zhou, Zuying Zhou, Danya
Published: , doi: 10.1088/1674-1137/43/12/124002
Differential and angle-integrated cross sections for the 10B(n, α)7Li, 10B(n, α0) 7Li and 10B(n, α1) 7Li* reactions have been measured at CSNS Back-n white neutron source. Two enriched (90%) 10B samples 5.0 cm in diameter and ~85.0 μg/cm2 in thickness each with an aluminum backing were prepared, and back-to-back mounted at the sample holder. The charged particles were detected using the silicon-detector array of the Light-charged Particle Detector Array (LPDA) system. The neutron energy En was determined by TOF (time-of-flight) method, and the valid α events were extracted from the En-Amplitude two-dimensional spectrum. With 15 silicon detectors, the differential cross sections of α-particles were measured from 19.2° to 160.8°. Fitted with the Legendre polynomial series, the (n, α) cross sections were obtained through integration. The absolute cross sections were normalized using the standard cross sections of the 10B(n, α)7Li reaction in the 0.3 − 0.5 MeV neutron energy region. The measurement neutron energy range for the 10B(n, α)7Li reaction is 1.0 eV≤En < 2.5 MeV (67 energy points), and for the 10B(n, α0) 7Li and 10B(n, α1) 7Li* reactions is 1.0 eV ≤ En < 1.0 MeV (59 energy points). The present results have been analyzed by the resonance reaction mechanism and the level structure of the 11B compound system, and compared with existing measurements and evaluations.
Electromagnetic properties of neutron-rich Ge isotopes
Hui Jiang, Xin-Lin Tang, Jia-Jie Shen, Yang Lei
Published: , doi: 10.1088/1674-1137/43/12/124110
The electric quadrupole moment $Q$ and the magnetic moment $\mu$ (or the $g$ factor) of low-lying states in even-even nuclei 72-80Ge and odd-mass nuclei 75-79Ge are studied in the framework of the nucleon pair approximation (NPA) of the shell model, assuming the monopole and quadrupole pairing plus quadrupole-quadrupole interaction. Our calculations reproduce well the experimental values of $Q(2_1^{+})$ and $g(2_1^+)$ for 72,74,76Ge, as well as the yrast energy levels of these isotopes. The structure of the $2_1^+$ states and the contributions of the proton and neutron components in $Q(2_1^{+})$ and $g(2_1^+)$ are discussed in the $SD$-pair truncated shell-model subspace. The overall trend of $Q(2_1^{+})$ and $g(2_1^+)$ as a function of the mass number $A$, as well as their signs, are found to originate essentially from the proton contribution. The negative value of $Q(2^+_1)$ in 72,74Ge is suggested to be due to the enhanced quadrupole-quadrupole correlation and configuration mixing.
Precision study of ${ {W^-W^+H}}$ production including parton shower effects at CERN Large Hadron Collider
Huan-Yu Bi, Ren-You Zhang, Wen-Gan Ma, Yi Jiang, Xiao-Zhou Li, Peng-Fei Duan
Published: , doi: 10.1088/1674-1137/43/12/123103
The precision study of $W^-W^+H$ production with subsequent $W^{\pm} \rightarrow l^{\pm} \overset{ _{(-)}}{\nu_{l}}$ and $H \rightarrow b\bar{b}$ decays at the Large Hadron Collider (LHC) aids in the investigation of Higgs gauge couplings and the search for new physics beyond the standard model. In this study, we calculate the shower-matched next-to-leading order QCD and electroweak (EW) corrections from the $q\bar{q}$ annihilation and photon-induced channels to the $W^-W^+H$ production at the $14~ {\rm TeV}$ LHC. We deal with the subsequent decays of Higgs and $W^{\pm}$ bosons by adopting the MADSPIN method. Both the integrated cross section and some kinematic distributions of $W^{\pm}$, H, and their decay products are provided. We find that the QCD correction significantly enhances the leading-order differential cross section, while the EW correction from the $q\bar{q}$ annihilation channel obviously suppresses it, especially in the high energy phase-space region, due to the Sudakov effect. The $q\gamma$- and $\gamma\gamma$-induced relative corrections are positive and insensitive to the transverse momenta of $W^{\pm}$, H, and their decay products. These photon-induced corrections compensate the negative $q\bar{q}$-initiated EW correction, and become the dominant EW contribution as the increment of the $pp$ colliding energy. The parton shower (PS) effects on kinematic distributions are not negligible. The relative PS correction to the b-jet transverse momentum distribution can exceed 100% in the high $p_{T, b}$ region. Moreover, we investigate the scale and PDF uncertainties, and find that the theoretical error of the ${\rm QCD}+{\rm EW}+q\gamma+\gamma\gamma$-corrected integrated cross section mainly originates from the renormalization scale dependence of the QCD correction.
Antiproton production in heavy-ion collisions at subthreshold energies
Zhao-Qing Feng
Published: , doi: 10.1088/1674-1137/44/1/014102
Within the framework of the Lanzhou quantum molecular dynamics model, the deep subthreshold antiproton production in heavy-ion collisions has been investigated thoroughly. The elastic scattering, annihilation and charge exchange reactions associated with antiproton channels are implemented in the model. The attractive antiproton potential extracted from the G-parity transformation of nucleon selfenergies reduces the threshold energies in meson-baryon and baryon-baryon collisions, and consequently enhances the antiproton yields to some extent. The calculated invariant spectra are consistent with the available experimental data. The primordial antiproton yields increase with the mass number of the colliding system. However, annihilation reactions reduce the antiproton production which becomes independent of the colliding partners. Anti-flow phenomena of antiprotons correlated with the mean field potential and annihilation mechanism is found by comparing them with the proton flows. Possible experiments at the high-intensity heavy-ion accelerator facility (HIAF) in China are discussed.
Charmonia and bottomonia in asymmetric magnetized hot nuclear matter
Rajesh Kumar, Arvind Kumar
Published: , doi: 10.1088/1674-1137/43/12/124109
We investigate the mass-shift of P-wave charmonium ($ {\chi_c}_0 $, $ {\chi_c}_1 $), and S and P-wave bottomonium ($ \eta_b $, $ \Upsilon $, $ {\chi_b}_0 $, and $ {\chi_b}_1 $) states in magnetized hot asymmetric nuclear matter using the unification of QCD sum rules (QCDSR) and the chiral $ SU(3) $ model. Within QCDSR, we use two approaches, i.e., the moment sum rule and the Borel sum rule. The magnetic field induced scalar gluon condensate $ \left\langle \frac{\alpha_{s}}{\pi} G^a_{\mu\nu} {G^a}^{\mu\nu} \right\rangle $ and the twist-2 gluon operator $ \left\langle \frac{\alpha_{s}}{\pi} G^a_{\mu\sigma} {{G^a}_\nu}^{\sigma} \right\rangle $ calculated in the chiral $ SU(3 $) model are utilised in QCD sum rules to calculate the in-medium mass-shift of the above mesons. The attractive mass-shift of these mesons is observed, which is more sensitive to magnetic field in the high density regime for charmonium, however less so for bottomonium. These results may be helpful to understand the decay of higher quarkonium states to the lower quarkonium states in asymmetric heavy ion collision experiments.
QCD analysis of CMS W+ charm measurements at LHC with ${\sqrt { s} = 7\; {\bf{TeV}}}$ and implications for strange PDF
Nijat Yalkun, Sayipjamal Dulat
Published: , doi: 10.1088/1674-1137/43/12/123101
We calculate cross-sections and cross-section ratios of a charm quark production in association with a W gauge boson at next-to-leading order QCD using MadGraph and CT10NNLO, CT14NNLO, and MSTW2008NNLO PDFs. We compare the results with measurements from the CMS detector at the LHC at a center-of-mass energy of 7 TeV. Moreover, we calculate absolute and normalized differential cross-sections as well as differential cross-section ratios as a function of the lepton pseudorapidity from the W boson decay. The correlation between the CT14NNLO PDFs and predictions for $W+$ charm data are studied as well. Furthermore, by employing the error PDF updating method proposed by the CTEQ-TEA group, we update CT14NNLO PDFs, and analyze the impact of CMS 7 TeV $W+$ charm production data to the original CT14NNLO PDFs. By comparison of the $g(x,Q)$, $s(x,Q)$, $u(x,Q)$, $d(x,Q)$, $\bar u(x,Q)$, and $\bar d(x,Q)$ PDFs at $Q=1.3$ GeV and $Q = 100$ GeV for the CT14NNLO and CT14NNLO+Wc, we see that the error band of the $s(x,Q)$ PDF is reduced in the region $x<0.4$, and the error band of $g(x,Q)$ PDF is also slightly reduced at region $0.01 < x<0.1$.
Weak cosmic censorship conjecture in BTZ black holes with scalar fields
Deyou Chen
Published: , doi: 10.1088/1674-1137/44/1/015101
The weak cosmic censorship conjecture in the near-extremal BTZ black hole has been tested using test particles and fields. It has been claimed that such a black hole can be overspun. In this paper, we review the thermodynamics and weak cosmic censorship conjecture in BTZ black holes using the scattering of a scalar field. The first law of thermodynamics in the non-extremal BTZ black hole is recovered. For the extremal and near-extremal black holes, due to the divergence of the variation of entropy, we test the weak cosmic censorship conjecture by evaluating the minimum of the function f, and find that both the extremal and near-extremal black holes cannot be overspun.
Weak cosmic censorship conjecture and thermodynamics in quintessence AdS black hole under charged particle absorption
Ke-Jian He, Xin-Yun Hu, Xiao-Xiong Zeng
Published: , doi: 10.1088/1674-1137/43/12/125101
Considering the cosmological constant as the pressure, this study addresses the laws of thermodynamics and weak cosmic censorship conjecture in the Reissner-Nordström-AdS black hole surrounded by quintessence dark energy under charged particle absorption. The first law of thermodynamics is found to be valid as a particle is absorbed by the black hole. The second law, however, is violated for the extremal and near-extremal black holes, because the entropy of these black hole decrease. Moreover, we find that the extremal black hole does not change its configuration in the extended phase space, implying that the weak cosmic censorship conjecture is valid. Remarkably, the near-extremal black hole can be overcharged beyond the extremal condition under charged particle absorption. Hence, the cosmic censorship conjecture could be violated for the near-extremal black hole in the extended phase space. For comparison, we also discuss the first law, second law, and the weak cosmic censorship conjecture in normal phase space, and find that all of them are valid in this case.
Determination of isospin asymmetry effects on α-decay
B. A. Gheshlagh, O. N. Ghodsi
Published: , doi: 10.1088/1674-1137/43/12/124105
In this study, we compared the effect of the isospin asymmetry of proton and neutron density distributions in the neutron skin-type (NST) case and in the Hartree-Fock formalism (HF) on the half-life of alpha emitters with the atomic number in the range of $82\leqslant Z\leqslant 92$. The NST case and HF formalism based on the Skyrme-SLy4 effective interaction reveal different isospin asymmetries for selected alpha emitters. Furthermore, the obtained results reveal an increase in the α-decay widths of about 30% for the NST case in comparison with the equivalent values obtained by HF formalism. The standard deviations for calculated half-lives within the NST case and HF formalism are about 0.438 and 0.391, respectively.
Vector hidden-bottom tetraquark candidate: Y(10750)
Zhi-Gang Wang
Published: , doi: 10.1088/1674-1137/43/12/123102
In this article, we take the scalar diquark and antidiquark operators as the basic constituents, and construct the $C\gamma_5\otimes\stackrel{\leftrightarrow}{\partial}_\mu\otimes \gamma_5C$ type tetraquark current to study Y(10750) with the QCD sum rules. The predicted mass $M_{Y}=10.75\pm0.10\,\rm{GeV}$ and width $\Gamma_Y= 33.60^{+16.64}_{-9.45}\,{\rm{MeV}}$ support the assignment of Y(10750) as the diquark-antidiquark type vector hidden-bottom tetraquark state, with a relative P-wave between the diquark and antidiquark constituents.
Constraining the anisotropy of the Universe with the Pantheon supernovae sample
Zhe Chang, Dong Zhao, Yong Zhou
Published: , doi: 10.1088/1674-1137/43/12/125102
We test the possible dipole anisotropy of the Finslerian cosmological model and the other three dipole-modulated cosmological models, i.e. the dipole-modulated ΛCDM, wCDM and Chevallier–Polarski–Linder (CPL) models, by using the recently released Pantheon sample of SNe Ia. The Markov chain Monte Carlo (MCMC) method is used to explore the whole parameter space. We find that the dipole anisotropy is very weak in all cosmological models used. Although the dipole amplitudes of four cosmological models are consistent with zero within the $1\sigma$ uncertainty, the dipole directions are close to the axial direction of the plane of the SDSS subsample in Pantheon. This may imply that the weak dipole anisotropy in the Pantheon sample originates from the inhomogeneous distribution of the SDSS subsample. A more homogeneous distribution of SNe Ia is necessary to constrain the cosmic anisotropy.
Recalibration of the binding energy of hypernuclei measured in emulsion experiments and its implications
Peng Liu(刘鹏), Jinhui Chen(陈金辉), Declan Keane, Zhangbu Xu(许长补), Yu-Gang Ma(马余刚)
Published: , doi: 10.1088/1674-1137/43/12/124001
The $ \Lambda $ separation energy for $ \Lambda $ hypernuclei, denoted $ B_\Lambda $, measured in 1967, 1968, and 1973 are recalibrated using the current best estimates of the mass of particles and nuclei. The recalibrated $ B_\Lambda $ are systematically larger (except in the case of $ ^6_\Lambda $He) than the originally published values by about 100 keV. The effect of this level of recalibration is very important for light hypernuclei, especially for the hypertriton. The early $ B_\Lambda $ values measured in 1967, 1968, and 1973 are widely used in theoretical research, and the new results provide better constraints for the conclusions of such studies.
Is X(3872) a bound state?
Pablo G. Ortega, Enrique Ruiz Arriola
Published: , doi: 10.1088/1674-1137/43/12/124107
All existing experimental evidence for the bound state nature of $X(3872)$ relies on observing its decay products, which are measured with a finite experimental mass resolution that is typically $\Delta m \geqslant 2 $ MeV , and much larger than its alleged binding energy, $B_X=0.00\,(18)$ MeV. On the other hand, we have found recently that there is a clear cancellation in the $1^{++}$ channel of the invariant $D {\bar D}^*$ mass around the threshold between continuum and the bound state. This is very much like a similar cancellation in the proton-neutron continuum with the deuteron in the $1^{++}$ channel. Based on comparative fits with a common Tsallis distribution of the experimental cross-sections for prompt production of deuterons and $X(3872)$ in pp collisions with a finite $p_T$, we find a strong argument for questioning the bound state nature of this state, which also suggests that the large observed production rate could be consistent with a half-bound state.
The structure of neutron-rich calcium isotopes studied by the shell model with realistic effective interactions
Xiao-Bao Wang, Yu-Hang Meng, Ya Tu, Guo-Xiang Dong
Published: , doi: 10.1088/1674-1137/43/12/124106
We study the structure of neutron-rich calcium isotopes in the shell model with realistic interactions. The CD-Bonn and Kuo-Brown (KB) interactions are used. As these interactions do not include the three-body force, their direct use leads to poor results. We tested whether the adjustment of the single particle energies (SPEs) would be sufficient to include the three-body correlations empirically. It turns out that the CD-Bonn interaction, after the adjustment of SPEs, gives good agreement with the experimental data for the energies and spectroscopy. For the KB interaction, both the SPEs and monopole terms require adjustments. Thus, the monopole problem is less serious for modern realistic interactions which include perturbations up to the third order. We also tested the effect of the non-central force on the shell structure. It is found that the effect of the tensor force in the CD-Bonn interaction is weaker than in the KB interaction.
Improved eikonal approach for charge exchange reactions at intermediate energies
Jing-Jing Li, Dan-Yang Pang, Yan-Lin Ye, Jian-Ling Lou, Xiao-Fei Yang, Yang Liu, Biao Yang
Published: , doi: 10.1088/1674-1137/43/12/124102
In order to describe charge exchange reactions at intermediate energies, we implemented as a first step the formulation of the normal eikonal approach. The calculated differential cross-sections based on this approach deviated significantly from the conventional DWBA calculations for CE reactions at 140 MeV/nucleon. Thereafter, improvements were made in the application of the eikonal approximation so as to keep a strict three-dimensional form factor. The results obtained with the improved eikonal approach are in good agreement with the DWBA calculations and with the experimental data. Since the improved eikonal approach can be formulated in a microscopic way, it is easy to apply to CE reactions at higher energies, where the phenomenological DWBA is a priori difficult to use due to the lack, in most cases, of the required phenomenological potentials.
Possibilities of producing superheavy nuclei in multinucleon transfer reactions based on radioactive targets
Long Zhu
Published: , doi: 10.1088/1674-1137/43/12/124103
The multinucleon transfer (MNT) process has been proposed as a promising approach to produce neutron-rich superheavy nuclei (SHN). MNT reactions based on the radioactive targets 249Cf, 254Es, and 257Fm are investigated within the framework of the improved version of a dinuclear system (DNS-sysu) model. The MNT reaction 238U + 238U was studied extensively as a promising candidate for producing SHN. However, based on the calculated cross-sections, it was found that there is little possibility to produce SHN in the reaction 238U + 238U. In turn, the production of SHN in reactions with radioactive targets is likely.
Nuclear mass parabola and its applications
Junlong Tian, Di Yuan, Yunyi Cui, Yun Huang, Ning Wang
Published: , doi: 10.1088/1674-1137/43/12/124104
We propose a method for extracting the properties of the isobaric mass parabola based on the total double $ \beta $-decay energies of isobaric nuclei. Two important parameters of the mass parabola, the location of the most $ \beta $-stable nuclei $ Z_{A} $ and the curvature parameter $ b_{A} $, are obtained for 251 A values, based on the total double $ \beta $-decay energies of nuclei compiled in the AME2016 database. The advantage of this approach is that the pairing energy term $ P_{A} $ caused by the odd-even variation can be removed in the process, as well as the mass excess $ M(A,Z_{A}) $ of the most stable nuclide for the mass number A, which are employed in the mass parabolic fitting method. The Coulomb energy coefficient $ a_{c} = 0.6910 $ MeV is determined by the mass difference relation for mirror nuclei, and the symmetry energy coefficient is also studied by the relation $ a_{\rm sym}(A) = 0.25b_{A}Z_{A} $.
Thermal production of charmonia in Pb-Pb collisions at ${ \sqrt{{ s}_{\bf{ {\rm NN}}}}{\bf {=5.02}}}$ TeV
Baoyi Chen
Published: , doi: 10.1088/1674-1137/43/12/124101
This work uses the Boltzmann transport model to study the thermal production of $J/\psi$ and $\psi(2S)$ in the quark gluon plasma (QGP) produced by $\sqrt{s_{\rm NN}}=5.02$ TeV Pb-Pb collisions. The $J/\psi$ nuclear modification factors are studied in detail alongside the mechanisms of primordial production and the recombination of charm and anti-charm quarks in the thermal medium. The $\psi(2S)$ binding energy is much smaller in the hot medium compared to the ground state; thus, $\psi(2S)$ with middle to low $p_{\rm T}$ can be thermally regenerated in the later stages of QGP expansions, enabling $\psi(2S)$ to inherit larger collective flows from the bulk medium. We quantitatively study the nuclear modification factors of both $J/\psi$ and $\psi(2S)$ in different centralities and transverse momentum bins for $\sqrt{s_{\rm NN}}=5.02$ TeV Pb-Pb collisions.