Chinese Physics C

Highlights

Holographic timelike entanglement entropy from Rindler method
Peng-Zhang He, Hai-Qing Zhang

2024, 48(11): 115113. doi: 10.1088/1674-1137/ad57a8

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For a Lorentzian invariant theory, the entanglement entropy should be a function of the domain of dependence of the subregion under consideration. More precisely, it should be a function of the domain of dependence and the appropriate cut-off. In this study, we refine the concept of cut-off to make it applicable to timelike regions and assume that the usual entanglement entropy formula also applies to timelike intervals. Using the Rindler method, the timelike entanglement entropy can be regarded as the thermal entropy of the CFT after the Rindler transformation plus a constant ${\rm i}\pi c/6$, where c denotes the central charge. The gravitational dual of the 'covariant' timelike entanglement entropy is presented following this method.
Form factor for Dalitz decays from J/ψ to light pseudoscalars
Chunjiang Shi, Ying Chen, Xiangyu Jiang, Ming Gong, Zhaofeng Liu, Wei Sun

2024, 48(11): 113105. doi: 10.1088/1674-1137/ad641b

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We calculate the form factor $M(q^2)$ for the Dalitz decay $J/\psi\to \gamma^*(q^2)\eta_{(N_f=1)}$ with $\eta_{(N_f)}$ being the SU($N_f$) flavor singlet pseudoscalar meson. The difference among the partial widths $\Gamma(J/\psi\to \gamma \eta_{(N_f)})$ at different $N_f$ can be attributed in part to the $N_f$ and quark mass dependences induced by the $\mathbf{U}_A(1)$ anomaly dominance. $M(q^2)$ in both $N_f=1,2$ is well described by the single pole model $M(q^2)=M(0)/(1-q^2/\Lambda^2)$. Combined with the known experimental results of the Dalitz decays $J/\psi\to Pe^+e^-$, the pseudoscalar mass $m_P$ dependence of the pole parameter $\Lambda$ is approximated by $\Lambda(m_P^2)=\Lambda_1(1-m_P^2/\Lambda_2^2)$ with $\Lambda_1={2.65(5)}~\mathrm{GeV}$ and $\Lambda_2={2.90(35)}~\mathrm{GeV}$. These results provide inputs for future theoretical and experimental studies on the Dalitz decays $J/\psi\to Pe^+e^-$.
A new perspective on the diffuse gamma-ray emission excess
En-Sheng Chen, Kun Fang, Xiao-Jun Bi

2024, 48(11): 115105. doi: 10.1088/1674-1137/ad72d4

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The Large High-Altitude Air Shower Observatory (LHAASO) recently published measurements of diffuse Galactic gamma-ray emission (DGE) in the 10−1000 TeV energy range. The measured DGE flux is significantly higher than the expectation from hadronic interactions between cosmic rays (CRs) and the interstellar medium. This excess has been proposed to originate from unknown extended sources produced by electron radiation, such as pulsar wind nebulae or pulsar halos (PWNe/halos). In this paper, we propose a new perspective to explain the DGE excess observed by LHAASO. The masking regions used in the LHAASO DGE measurement may not fully encompass the extended signals of $\textit{known} $ PWNe/halos. By employing a two-zone diffusion model for electrons around pulsars, we find that the DGE excess in most regions of the Galactic plane can be well explained by the signal leakage model under certain parameters. Our results indicate that this signal leakage from known sources and contributions from unresolved sources should be considered as complementary in explaining the DGE excess.

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Phase transition of modified thermodynamics of the Kerr-AdS black hole
Qin Liu, Xiaoning Wu, Xiao Zhang

Published: 2024-10-30

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Published: 2024-10-30

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Analytic continuation in the coupling constant for resonances in $ {}^9_{\Lambda} $Be
Hantao Zhang, Dong Bai, Zhongzhou Ren

Published: 2024-10-30

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Published: 2024-10-30

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Probing axion-like particles in leptonic decays of heavy mesons
Gang Yang, Tianhong Wang, Guo-Li Wang

Published: 2024-10-30

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Published: 2024-10-30

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Charm physics with overlap fermions on 2+1-flavor domain wall fermion configurations
Dong-Hao Li, Ying Chen, Ming Gong, Keh-Fei Liu, Zhaofeng Liu, Ting-Xiao Wang, (χQCD Collaboration)

2024, 48(12): 123104-123104-13. doi: 10.1088/1674-1137/ad736f

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Decay constants of pseudoscalar mesons D, $ D_s $, $ \eta_c $ and vector mesons $ D^* $, $ D_s^* $, $ J/\psi $ are determined from the $ N_f=2+1 $ lattice QCD at a lattice spacing $ a\sim0.08 $ fm. For vector mesons, the decay constants defined by tensor currents are given in the $ {{\overline{{\rm{MS}}}}} $ scheme at $ 2 $ GeV. The calculation is performed on domain wall fermion configurations generated by the RBC-UKQCD collaborations and the overlap fermion action is used for the valence quarks. Comparing the current results with our previous results at a coarser lattice spacing $ a\sim0.11 $ fm provides a better understanding of the discretization error. We obtain $ f_{D_s^*}^T({{\overline{{\rm{MS}}}}},\text{ 2 GeV})/f_{D_s^*}=0.909(18) $ with a better precision than our previous result. Combining our $ f_{D_s^*}=277(11) $ MeV with the total width of $ D_s^* $ determined in a recent study gives a branching fraction $ 4.26(52)\times10^{-5} $ for $ D_s^* $ leptonic decay.

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Unraveling the early universe’s equation of state and primordial black hole production with PTA, BBN, and CMB observations
Qing-Hua Zhu, Zhi-Chao Zhao, Sai Wang, Xin Zhang

2024, 48(12): 125105-125105-9. doi: 10.1088/1674-1137/ad79d5

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Pulsar timing array (PTA) data releases show strong evidence for a stochastic gravitational-wave background in the nanohertz band. When the signal is interpreted by a scenario of scalar-induced gravitational waves (SIGWs), we encounter overproduction of primordial black holes (PBHs). We wonder if varying the equation of state (EoS) of the early Universe can resolve this issue and thereby lead to a consistent interpretation of the PTA data. Analyzing a data combination of PTA, big-bang nucleosynthesis, and cosmic microwave background, we find that an epoch with EoS $w\sim{\cal{O}}(10^{-2})$ between the end of inflation and the onset of radiation domination can significantly suppress the production of PBHs, leading to alleviation of the PBH-overproduction issue. With the inferred interval $w=0.44_{-0.40}^{+0.52}$ at 95% confidence level, our scenario can interpret the PTA data just as well as the conventional scenario of SIGWs produced during the radiation domination.

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The thermodynamic stability and phase structure of the Einstein-Euler-Heisenberg-AdS black holes
Yinan Zhao, Hongbo Cheng

2024, 48(12): 125106-125106-9. doi: 10.1088/1674-1137/ad79d4

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In both the canonical ensemble and grand canonical ensemble, the thermodynamic stability and phase structure of Einstein-Euler-Heisenberg-AdS black holes are studied. We derive the Hawking temperature, Helmholtz free energy, Gibbs potential, entropy and heat capacity of the black holes. We compute the minimum temperature to find that a phase transition may happen at the lowest point. The entropy-temperature diagram consists of two parts. The upper part belonging to the large black holes under the influence from the electromagnetic self-interactions keeps the positive heat capacity, leading the huge compact objects to survive. The lower curves corresponding to small black holes show that the heat capacity of the tiny black holes is negative, which means that the nonlinear-effect-corrected smaller sources will evaporate. The further discussions show that the nonlinear effect modifies the thermodynamic quantities, but the corrections limited by the nonlinear factor μ with allowed values can not change the properties and the phase structure fundamentally and thoroughly. We argue that the influence from self-interaction can not make the Einstein-Euler-Heisenberg-AdS black holes to split under the second law of thermodynamics.

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Current Issued

2024 Vol. 48, No. 11
Published: 29 October 2024

Particles And Fields
Nuclear Physics
Particle And Nuclear Astrophysics And Cosmology