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2025-4 Contents
2025, 49(4): 1-2.
Abstract:
PARTICLES AND FIELDS
Search for the lepton number violation decay ϕ → π+π+e−e− via J/ψ → ϕη
M. Ablikim, M. N. Achasov, P. Adlarson, O. Afedulidis, X. C. Ai, R. Aliberti, A. Amoroso, M. R. An, Q. An, Y. Bai, O. Bakina, I. Balossino, Y. Ban, H.-R. Bao, V. Batozskaya, K. Begzsuren, N. Berger, M. Berlowski, M. Bertani, D. Bettoni, F. Bianchi, E. Bianco, 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, G. R. Che, Y. Z. Che, G. Chelkov, C. Chen, Chao Chen, G. Chen, H. S. Chen, M. L. Chen, S. J. Chen, S. L. Chen, S. M. Chen, T. Chen, X. R. Chen, X. T. Chen, Y. B. Chen, Y. Q. Chen, Z. J. Chen, Z. Y. Chen, S. K. Choi, G. Cibinetto, S. C. Coen, 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, B. Ding, X. X. Ding, Y. Ding, J. Dong, L. Y. Dong, M. Y. Dong, X. Dong, M. C. Du, S. X. Du, Z. H. Duan, P. Egorov, Y. H. Fan, J. Fang, S. S. Fang, W. X. Fang, Y. Fang, Y. Q. Fang, R. Farinelli, L. Fava, F. Feldbauer, G. Felici, C. Q. Feng, J. H. F
2025, 49(4): 043001. doi: 10.1088/1674-1137/ada350
Abstract:
Using an electron-positron collision data sample corresponding to \begin{document}$ (1.0087\pm0.0044)\times10^{10} $\end{document} \begin{document}$ J/\psi $\end{document}events collected using the BESIII detector at the BEPCII collider, we firstly search for the lepton number violation decay \begin{document}$ \phi \to \pi^+ \pi^+ e^- e^- $\end{document} via \begin{document}$ J/\psi\to \phi\eta $\end{document}. No obviously signals are found. The upper limit on the branching fraction of \begin{document}$ \phi \to \pi^+ \pi^+ e^- e^- $\end{document}is set to be \begin{document}$ 1.3\times10^{-5} $\end{document} at the 90% confidence level.
Constraining dark matter models with a light mediator from the CDEX-10 experiment at China Jinping Underground Laboratory
Qi-Yuan Nie, Wen-Han Dai, Hao Ma, Qian Yue, Ke-Jun Kang, Yuan-Jing Li, Hai-Peng An, C. Greeshma, Jian-Ping Chang, Yun-Hua Chen, Jian-Ping Cheng, Zhi Deng, Chang-Hao Fang, Xin-Ping Geng, Hui Gong, Tao Guo, Xu-Yuan Guo, Li He, Jin-Rong He, Han-Xiong Huang, Tu-Chen Huang, S. Karmakar, Jian-Min Li, Jin Li, Yu-Lan Li, Hau-Bin Li, Ming-Chuan Li, Han-Yu Li, Qian-Yun Li, Ren-Ming-Jie Li, Xue-Qian Li, Yi-Fan Liang, Bin Liao, Fong-Kay Lin, Shin-Ted Lin, Jia-Xuan Liu, Yan-Dong Liu, Yuan-Yuan Liu, Shu-Kui Liu, Yu Liu, Hui Pan, Ning-Chun Qi, Jie Ren, Xi-Chao Ruan, Man-Bin Shen, Manoj Kumar Singh, Wen-Liang Sun, Tian-Xi Sun, Chang-Jian Tang, Yang Tian, Hong-Fei Wan, Jun-Zheng Wang, Yu-Feng Wang, Guang-Fu Wang, Li Wang, Qing Wang, Henry-Tsz-King Wong, Yu-Cheng Wu, Hao-Yang Xing, Kai-Zhi Xiong, Rui Xu, Yin Xu, Tao Xue, Yu-Lu Yan, Li-Tao Yang, Nan Yi, Chun-Xu Yu, Hai-Jun Yu, Xiao Yu, Ming Zeng, Zhi Zeng, Zhen-Hua Zhang, Zhen-Yu Zhang, Peng Zhang, Feng-Shou Zhang, Lei Zhang, Ji-Zhong Zhao, Kang-Kang Zhao, Ming-Gang Zhao, Ji-Fa
2025, 49(4): 043002. doi: 10.1088/1674-1137/ada914
Abstract:
We search for nuclear recoil signals of dark matter (DM) models with a light mediator using data taken from a p-type point-contact germanium detector of the CDEX-10 experiment at the China Jinping Underground Laboratory. The 90% confidence level upper limits on the DM-nucleon interaction cross section from 205.4 kg-day exposure data are derived, excluding the new parameter space in 2−3 GeV DM mass when the mediator mass is comparable to or lower than the typical momentum transfer. We further interpret our results to constrain a specific self-interacting DM model with a light mediator coupling to the photon through kinetic mixing and set experimental limits on the model parameter region favored by astrophysical observations.
Probing heavy charged Higgs bosons at gamma-gamma colliders using a multivariate technique
Ijaz Ahmed, Abdul Quddus, Jamil Muhammad, Muhammad Shoaib, Saba Shafaq
2025, 49(4): 043101. doi: 10.1088/1674-1137/ada0b4
Abstract:
This study explores the production of charged Higgs particles through photon-photon collisions within the context of the Two Higgs Doublet Model, including one-loop-level scattering amplitudes of electroweak and QED radiation. The cross-section has been scanned for the plane (\begin{document}$m_{\phi^{0}}, \sqrt{s}$\end{document}) to investigate the process of \begin{document}$\gamma\gamma \rightarrow H^{+}H^{-}$\end{document}. Three particular numerical scenarios, i.e., low-\begin{document}$m_{H}$\end{document}, non-alignment, and short-cascade are employed. The decay channels for charged Higgs particles are examined using \begin{document}$h^{0}$\end{document} for low-\begin{document}$m_{H^{0}}$\end{document} and \begin{document}$H^{0}$\end{document}for non-alignment and short-cascade scenarios incorporating the new experimental and theoretical constraints along with the analysis for cross-sections. We find that, at a low energy, the cross-section is consistently higher for all scenarios. However, as\begin{document}$\sqrt{s}$\end{document} increases, it reaches a peak value at 1\begin{document}$~$\end{document}TeV for all benchmark scenarios. The branching ratio of the decay channels indicates that for non-alignment, the mode of decay \begin{document}$W^{\pm} h^{0}$\end{document} takes control, and for a short cascade, the prominent decay mode remains \begin{document}$t\overline {b}$\end{document}, whereas in the low-\begin{document}$m_{H}$\end{document}scenario, the dominant decay channel is of \begin{document}$W^{\pm} h^{0}$\end{document}. In our research, we employ contemporary machine-learning methodologies to investigate the production of high-energy Higgs bosons within a 3.0 TeV \begin{document}$\gamma\gamma$\end{document} collider. We have used multivariate approaches such as Boosted Decision Trees (BDT), LikelihoodD, and Multilayer Perceptron (MLP) to show the observability of heavy-charged Higgs Bosons versus the most significant Standard Model backgrounds. The purity of the signal efficiency and background rejection are measured for each cut value.
Muon g − 2 with SU(2)L multiplets
Takaaki Nomura, Hiroshi Okada
2025, 49(4): 043102. doi: 10.1088/1674-1137/adabcf
Abstract:
We propose a simple model to obtain a sizable muon anomalous magnetic dipole moment (muon \begin{document}$ g-2 $\end{document}) that introduces several \begin{document}$ S U(2)_L $\end{document} multiplet fields without any additional symmetries. The neutrino mass matrix is simply induced via a type-II seesaw scenario in terms of \begin{document}$ S U(2)_L $\end{document} triplet Higgs with \begin{document}$ U(1)_Y $\end{document} hypercharge 1. In addition, we introduce an \begin{document}$ S U(2)_L $\end{document} quartet vector-like fermion with hypercharge \begin{document}$ 1/2 $\end{document} and scalar with hypercharge \begin{document}$ 3/2 $\end{document}. The quartet fermion plays a crucial role in explaining muon \begin{document}$ g-2 $\end{document} causing the chiral flip inside a loop diagram with the mixing of triplet and quartet scalar bosons via the standard model Higgs. We conduct a numerical analysis and search for the allowed region in our parameter space and demonstrate the collider physics.
Unstable mode of the net-baryon density near the spinodal decomposition region
Shanjin Wu
2025, 49(4): 043103. doi: 10.1088/1674-1137/adb561
Abstract:
This paper investigates conserved net-baryon multiplicity fluctuations near the spinodal decomposition region based on the stochastic diffusion equation, model B. The convex anomaly in the spinodal region induces the unstable mode, and the correlation function dominates at the harder mode. The unstable mode results in oscillating behavior of second-order multiplicity fluctuations with increasing spatial interval. This oscillating behavior of multiplicity fluctuations with respect to acceptance may indicate the existence of the convex anomaly of spinodal decomposition.
ρ meson form factors and parton distribution functions in impact parameter space
Jin-Li Zhang
2025, 49(4): 043104. doi: 10.1088/1674-1137/adab61
Abstract:
This study investigates the form factors and impact parameter space parton distribution functions of the ρ meson derived from the generalized parton distributions within the Nambu–Jona-Lasinio model framework, employing a proper time regularization scheme. We compare the charge \begin{document}$G_C$\end{document}, magnetic \begin{document}$G_M$\end{document}, and quadrupole \begin{document}$G_Q$\end{document} form factors with lattice data. The dressed form factors, \begin{document}$G_C^D$\end{document} and \begin{document}$G_M^D$\end{document}, exhibit good agreement with lattice results; however, \begin{document}$G_Q^D$\end{document} is found to be harder than what is observed in lattice calculations. The Rosenbluth cross section for elastic electron scattering on a spin-one particle can be expressed through the structure functions \begin{document}$A(Q^2)$\end{document} and \begin{document}$B(Q^2)$\end{document}. Additionally, the tensor polarization \begin{document}$T_{20}(Q^2,\theta)$\end{document} can also be formulated in terms of these form factors. We analyze the structure functions \begin{document}$A(Q^2)$\end{document}, \begin{document}$B(Q^2)$\end{document} and tensor polarization function \begin{document}$T_{20}(Q^2,\theta)$\end{document}; our findings quantitatively align with predicted values across various limits. In impact parameter space, we examine parton distribution functions along with their dependence on longitudinal momentum fraction x and impact parameter \begin{document}$\boldsymbol{b}_{\perp}$\end{document}. The width distributions in impact parameter space reveal that the range of the charge distribution \begin{document}$ q_C(x,\boldsymbol{b}_{\perp}^2)$\end{document} is the most extensive. In contrast, the transverse magnetic radius falls within a moderate range, while the quadrupole distribution \begin{document}$q_Q(x,\boldsymbol{b}_{\perp}^2) $\end{document} demonstrates the narrowest extent.
NUCLEAR PHYSICS
Azimuthal correlation anisotropies in p + p collisions simulated using Pythia
Manuel Sebastian Torres, Yicheng Feng, Fuqiang Wang
2025, 49(4): 044001. doi: 10.1088/1674-1137/adacc3
Abstract:
Stimulated by a keen interest in possible collective behavior in high-energy proton-proton and proton-nucleus collisions, we study two-particle angular correlations in pseudorapidity and azimuthal differences in simulated p + p interactions using the Pythia 8 event generator. Multi-parton interactions and color connection are included in these simulations, which have been perceived to produce collectivity in final-state particles. Meanwhile, contributions from genuine few-body nonflow correlations, not of collective flow behavior, are known to be severe in these small-system collisions. We present our Pythia correlation studies pedagogically and report azimuthal harmonic anisotropies analyzed using several methods. We observe anisotropies in these Pythia simulated events qualitatively and semi-quantitatively, similar to experimental data. Our findings highlight the delicate nature of azimuthal anisotropies in small-system collisions and provide a benchmark that can aid in improving data analysis and interpreting experimental measurements in small-system collisions.
Resonance of hypernuclei with complex momentum representation
Hantao Zhang, Chao-Feng Chen, Xian-Rong Zhou, Zhongzhou Ren
2025, 49(4): 044101. doi: 10.1088/1674-1137/ad9a8c
Abstract:
By combining the Skyrme-Hartree-Fock method with complex momentum representation (CMR), the resonant states of \begin{document}$ {}^{17}_\Lambda $\end{document}O, \begin{document}$ {}^{41}_{\Lambda} $\end{document}Ca, \begin{document}$ {}^{49}_{\Lambda} $\end{document}Ca, and \begin{document}$ {}^{57}_\Lambda $\end{document}Ni were investigated. The phase shifts for hyperon-nucleus elastic scattering were determined with continuum level density (CLD), and the scattering length as well as the resonance energy were obtained by utilizing the effective range expansion. Our method, abbreviated as CMR-CLD, exhibits good consistency with traditional approaches and provides ground work for investigating scattering and resonance problems in deformed and multi-hyperon hypernuclei.
Investigation of heavy particle radioactivity and spontaneous fission of even-Z superheavy nuclei
Kirandeep Sandhu, Gurjit Kaur, Manoj K. Sharma
2025, 49(4): 044102. doi: 10.1088/1674-1137/ada126
Abstract:
The preformed cluster model (PCM) is applied to investigate the heavy particle radioactivity (HPR) and spontaneous fission (SF) processes for even-Z superheavy nuclear systems. Different proximity potentials are used to calculate the decay half-lives of \begin{document}$Z=112-120 $\end{document} nuclei. The fragmentation potential and preformation distribution suggest that SF is the major contributor up to \begin{document}$Z=114 $\end{document}, and HPR starts competing for heavier nuclei. The heavy cluster emission is supported by Pb-magicity, whereas SF is reinforced owing to the deformations of fission fragments. The heavy cluster decay half-lives (log\begin{document}$ _{10} $\end{document}TC) are calculated using the PCM and are compared with the estimates of the analytical super asymmetric fission (ASAF) model. The calculated log\begin{document}$ _{10} $\end{document}TC values agree well with the ASAF measurements when using the Prox-00 and Mod Prox-00 versions of potentials. However, Prox-77, Prox-88, and Prox-BW-91 are not appropriate to address the log\begin{document}$ _{10} $\end{document}TC for \begin{document}$ Z \geq 116$\end{document} nuclei. To resolve this, we include Z-dependence in the radius parameters. Interestingly, the half-lives match the ASAF data after the inclusion of Z-dependence. The branching ratios are also calculated for superheavy nuclei and compared with the estimates of unified description (UD) formula, universal curve (UNIV), universal decay law (UDL), Horoi formula, and ASAF measurements. Furthermore, the SF half-lives (\begin{document}$T_{\rm SF}$\end{document}) of \begin{document}$ ^{282} $\end{document}Cn, \begin{document}$ ^{284} $\end{document}Cn, \begin{document}$ ^{284} $\end{document}Fl, and \begin{document}$ ^{286} $\end{document}Fl superheavy nuclei are estimated through various proximity potentials. Among them, Prox-00 is appropriate for addressing the experimental data. Using this potential, the SF half-lives are estimated through the PCM for \begin{document}$Z=116-120 $\end{document} isotopes at different neck-length parameters. Finally, the scaled total kinetic energy (TKE) values are compared with the available data.
Anisotropic flow, flow fluctuation, and flow decorrelation in relativistic heavy-ion collisions: the roles of sub-nucleon structure and shear viscosity
Jie Zhu, Xiang-Yu Wu, Guang-You Qin
2025, 49(4): 044103. doi: 10.1088/1674-1137/ada7d1
Abstract:
We study the transverse momentum (\begin{document}$p_T$\end{document}) differential anisotropic flow and flow fluctuation in Pb+Pb collisions at \begin{document}$\sqrt{s_{_{NN}}}$\end{document}=5.02 TeV at the LHC. A (3+1)-dimensional CLVisc hydrodynamics framework with fluctuating TRENTO (or AMPT) initial conditions is utilized to simulate the space-time evolution of the quark-gluon plasma (QGP) medium. The effects of shear viscosity and the sub-nucleon structure on anisotropic flow and flow fluctuation are analyzed. Our result shows that shear viscosity tends to suppress both flow coefficients (\begin{document}${v_2\{2}\}$\end{document}, \begin{document}${v_2\{4\}}$\end{document}, and \begin{document}${\langle v_2\rangle}$\end{document}) and flow fluctuation (\begin{document}${\sigma_{v_2}}$\end{document}) owing to its smearing effect on local density fluctuation. The flow coefficients appear to be insensitive to the sub-nucleon structure, whereas the flow fluctuation \begin{document}${\sigma_{v_2}}$\end{document} tends to be suppressed by the sub-nucleon structure in central collisions but enhanced in peripheral collisions. After taking into account the sub-nucleon structure effect, our numerical result can qualitatively describe the relative flow fluctuations (\begin{document}${v_2\{4\}/v_2\{2\}}$\end{document}, \begin{document}$F({v_2})$\end{document}) measured by the ALICE Collaboration at the LHC. We further investigate the effects of shear viscosity, sub-nucleon structure, and initial condition model on the flow angle and flow magnitude decorrelations (\begin{document}${A_2^f}$\end{document}, \begin{document}${M_2^f}$\end{document}) using the four-particle correlation method. We find that the flow decorrelation effect is typically stronger in central collisions than in peripheral collisions. The flow angle decorrelation is found to be insensitive to the shear viscosity and sub-nucleon structure, whereas the flow magnitude decorrelation shows quite different behaviors when using the TRENTO and AMPT initial condition models. Our study sheds light on the anisotropic flow, transport properties, and initial structure of the QGP created in high-energy nuclear collisions.
Reaction rate of radiative p12C capture in a modified potential cluster model
S. B. Dubovichenko, N. A. Burkova, A. S. Tkachenko, A. Samratova
2025, 49(4): 044104. doi: 10.1088/1674-1137/ada34d
Abstract:
The astrophysical S-factor of the 12C(p, γ0)13N reaction at energies from 25 keV to 5 MeV within the framework of a modified potential cluster model with forbidden states is considered. The experimental phase shifts resonant \begin{document}$ {\delta _{^2{S_{1/2}}}} $\end{document}, \begin{document}$ {\delta _{^2{P_{3/2}}}} $\end{document}, and non-resonant \begin{document}$ {\delta _{^2{D_{3/2}}}} $\end{document}at the energies up to Ec.m. = 3 MeV are reproduced with high accuracy, which provides the appropriate agreement with the experimental data for the S-factor of 1950−2023 years. Two sets of asymptotic constant are used: Set I refers to Cw = 1.30(2), and Set II refers to Cw = 1.37(1). Set I leads to the astrophysical factor S(25) = 1.34 ± 0.02 keV·b, which is in agreement with data by Skowronski et al., 2023 – 1.34 ± 0.09 keV·b; Set II gives S(25) = 1.49 ± 0.02 keV·b, which is in agreement with data by Kettner et al., 2023 – 1.48 ± 0.09 keV·b. The reaction rates of 12C(p, γ0)13N at temperatures T9 from 0.001 to 10 are calculated. The detailed comparison with some models, the R-matrix approach, and NACRE II data for reaction rates is considered.
Bremsstrahlung emission from nucleon-nucleus reactions in dense medium of compact stars
Sergei P. Maydanyuk, Ju-Jun Xie, Kostiantyn A. Shaulskyi
2025, 49(4): 044105. doi: 10.1088/1674-1137/ada377
Abstract:
Bremsstrahlung photons emitted during nucleon-nucleus reactions in compact stars are investigated. The influence of stellar medium density on emission intensity is studied from a quantum perspective for the first time. A bremsstrahlung model is generalized, where a new term describing the influence of the stellar medium is added to interactions between nucleons and nuclei (in the framework of a nuclear model of deformed oscillatoric shells). Polytropic EOS, Chandrasekar EOS, and Harrison-Wheeler EOS are employed for calculation. Haensel and Potekhin's unified EOS of neutron-star matter based on FPS and SLy EOSs are used for tests. Bremsstrahlung calculations are tested on existing measurements of bremsstrahlung in the scattering of protons off 197Au nuclei at a proton beam energy of \begin{document}$E_{ p}=190$\end{document} MeV. Many properties of bremsstrahlung emitted from nuclear processes in the stellar medium of compact stars are studied for the first time. In particular, the spectra of photons in the scattering of protons and neutrons off 4He, 8Be, 12C, 16O, 24Mg, 40Ca, 56Fe are estimated based on stellar medium density. The medium of white dwarfs has a small influence on the bremsstrahlung emission from nuclear processes, while bremsstrahlung emission is intensive in neutron stars and it is changed in dependence on stellar medium and structure.
Analysis of the ${\boldsymbol K^- \boldsymbol p \to \boldsymbol\gamma \boldsymbol\Lambda}$ reaction
Yi Pan, Rong Li, Bo-Chao Liu
2025, 49(4): 044106. doi: 10.1088/1674-1137/ada7ce
Abstract:
In this work, we study the \begin{document}$K^- p \to \gamma \Lambda$\end{document} reaction in an effective Lagrangian approach and isobar model. Compared to previous studies using a Regge-plus-resonance model, we consider the contributions of the t-channel (K and \begin{document}$K^*$\end{document}) and u-channel (proton) exchanges explicitly as the background contribution. To restore the gauge invariance of the amplitude violated by introducing the phenomenological form factors, we employ two different methods from the literature. Then, we discuss the roles of possible resonance contributions in this reaction and present predictions of Λ polarization based on various models. We find that the contribution of the background terms plays an important role in the present reaction. Meanwhile, the \begin{document}$\Lambda(1520)$\end{document}, \begin{document}$\Sigma(1660)$\end{document}, and \begin{document}$\Sigma(1670)$\end{document} resonances may also contribute to this reaction. Due to the uncertainties of the present data and relatively small contributions of the hyperon resonances, we cannot identify the roles of various hyperon resonances in the present work. However, we show that the measurement of the spin polarization of the final Λ will be helpful to verify various models.
Application of the Woods-Saxon potential in studying quadrupole and octupole excited states using machine learning
Hadi Sobhani, Yan-An Luo
2025, 49(4): 044107. doi: 10.1088/1674-1137/ada5c9
Abstract:
In this study, the energy bands of quadrupole and octupole excited states are investigated. This is achieved by employing the Bohr Hamiltonian, incorporating quadrupole and octupole deformations whose variables are accurately separated. Subsequently, the Woods-Saxon potential is added to the problem. Because this problem cannot yield suitable solutions using conventional approximations, we solve it numerically using machine learning. A detailed description is given of how wave functions and their associated energies are obtained. Throughout this procedure, we demonstrate how machine learning aids us in easily accomplishing our objective. We examine and analyze the energy spectrum and possible multipole transitions for candidate isotopes \begin{document}$ ^{226} $\end{document}Ra and \begin{document}$ ^{226} $\end{document}Th.
Exposing the dead-cone effect of jet quenching in QCD medium
Yun-Fan Liu, Wei Dai, Ben-Wei Zhang, Enke Wang
2025, 49(4): 044108. doi: 10.1088/1674-1137/ada7cf
Abstract:
When an energetic parton traverses the hot QCD medium, it may suffer from multiple scattering and lose its energy. The medium-induced gluon radiation for a massive quark will be suppressed relative to that of a light quark due to the dead-cone effect. The development of new declustering techniques of jet evolution makes a direct study of the dead-cone effect in the QCD medium possible for the first time. In this work, we compute the emission angle distribution of the charm-quark-initiated splittings in D0 meson tagged jet and that of the light parton-initiated splittings in an inclusive jet in p+p and Pb+Pb at 5.02 TeV by utilizing the declustering techniques of jet evolution. The heavy quark propagation and induced energy loss in the QCD medium are simulated with the SHELL model based on the Langevin equation. By directly comparing the emission angle distributions of charm-quark-initiated splittings with those of light parton-initiated splittings at the same energy intervals of the initial parton, we provide insights into the fundamental splitting structure in A+A collisions, thereby exploring the possible observation of the dead-cone effect in medium-induced radiation. We further investigate the case of the emission angle distributions normalized to the number of splittings and find the dead-cone effect will broaden the emission angle of the splitting and reduce the possibility for such splitting to occur, leading the massive parton to lose less energy. We also find that the collisional energy loss mechanism has a negligible impact on the medium modification to the emission angle distribution of the charm-quark-initiated splittings for D0 meson-tagged jets.
Semi-microscopic analysis of 20Ne +130Te elastic and inelastic scattering at 15.3 A MeV
Kassem O. Behairy, M. A. Hassanain, M. Anwar, A. Hemmdan
2025, 49(4): 044109. doi: 10.1088/1674-1137/ad9305
Abstract:
The new measured data of elastic and inelastic 20Ne+130Te scattering at an energy of 15.3 A MeV are analyzed in framework of the nuclear optical potential. Three types of semi-microscopic potentials are used: the real part is calculated using a double folding model in conjunction with the conventional phenomenological Woods-Saxon (WS) potential for the imaginary part. Two real cluster models are constructed using the cluster structure of 20Ne nucleus as 5α and α+16O. The real part of the third potential is generated using a CDM3Y6 interaction employed for comparison. Three excited energies to the superposition of the projectile and target states, ground-state (Quasi), 1.6 and 2.5 MeV are investigated using deformed potentials. The contributions of these states are calculated using a one-step distorted wave Born approximation and coupled Channels approaches. Successful calculations and results using semi-microscopic potentials in simple one-channel and coupled channels are obtained. The values of cross section and volume integrals require more contributions to enable more comparisons regarding this project.
An empirical formula of nuclear β-decay half-lives with the transition-strength contribution
Lei Tian, Wei-Feng Li, Ji-Yu Fang, Zhong-Ming Niu
2025, 49(4): 044110. doi: 10.1088/1674-1137/ad9303
Abstract:
An empirical formula of nuclear β-decay half-lives is proposed by including the transition-strength contribution. The inclusion of the transition-strength contribution can reduce nuclear β-decay half-lives by about an order of magnitude, and its effect gradually increases toward the neutron-rich or heavy nuclear regions. For nuclear β-decay half-lives less than 1 s, the empirical formula can describe the experimental data within approximately2 times, which is more accurate than the sophisticated microscopic models. The transition-strength contribution can also be effectively considered by refitting the parameters of other empirical formulas without the transition-strength term although they will still significantly deviate from the new empirical formula in light or heavy neutron-rich nuclear regions. This indicates that the inclusion of the transition-strength contribution in the empirical formula is crucial for the global description of nuclear β-decay half-lives. The extrapolation ability of the new empirical formula was verified by the newly measured β-decay half-lives.
Effects of nuclear deformation and surface polarization on proton-emission half-lives
Hanlin Wang, Zhen Wang, Dong Bai, Dongdong Ni, Zhongzhou Ren
2025, 49(4): 044111. doi: 10.1088/1674-1137/ada95e
Abstract:
Proton radioactivity is used to investigate the characteristics of unstable neutron-deficient nuclei beyond the proton dripline. Based on the tunneling of one proton through the potential barrier formed by Woods-Saxon plus expanded Coulomb potentials, the half-lives of various proton emitters are calculated using distorted wave Born approximations. In particular, deformation and nuclear surface polarization are considered in our calculation, and their effects on proton-emission half-lives are researched. An analytic formula expressing the relationship between spectroscopic factors and deformation and polarization, which significantly reduces the deviations of calculated half-lives from experimental data, is proposed as well. Moreover, inspired by the new experimental results for the first proton emitter ever discovered,\begin{document}$ ^{53}\text{Co}^m $\end{document}[L. G. Sarmiento et al., Nat. Commun. 14, 5961 (2023)], we calculate its two proton-emission branches and interpret the partial half-lives. It is noteworthy that this high-spin isomer has some particular characteristics, including diminutive spectroscopic factors and stronger daughter-proton interactions, that considerably enhance the effects of deformation and polarization.
PARTICLE AND NUCLEAR ASTROPHYSICS AND COSMOLOGY
Cosmological perturbations in the energy-momentum squared gravity theory: constraints from gravitational wave standard sirens and redshift space distortions
Qi-Ming Fu, Xin Zhang
2025, 49(4): 045101. doi: 10.1088/1674-1137/adab62
Abstract:
We investigate the linear cosmological perturbations in the context of the so-called energy-momentum squared gravity (EMSG) theory. Recent research shows that the EMSG theory can reproduce a viable background cosmological evolution comparable to ΛCDM, whereas the matter-dominated era exhibits slight distinctions. In this paper, we focus on power-law EMSG models and derive the equations for the linear cosmological perturbations. We explore the propagation of the gravitational wave (GW) and the growth of matter density perturbation at the first order, and we estimate the model parameters from the simulated GW and observed redshift space distortion data. Our analysis reveals that the model parameters should be small and positive in the \begin{document}$ 1\sigma $\end{document} confidence interval, which indicates that the theory agrees closely with the observational data and can be considered an alternative to the standard cosmological model.
Modified power law cosmology: theoretical scenarios and observational constraints
L. K. Sharma, Suresh Parekh, Saibal Ray, Anil Kumar Yadav, Maxim Khlopov, Kalyani C.K. Mehta
2025, 49(4): 045102. doi: 10.1088/1674-1137/adaa57
Abstract:
This research paper examines a cosmological model in flat space-time via \begin{document}$ f(R,G) $\end{document} gravity, where R and G are the Ricci scalar and Gauss-Bonnet invariant, respectively. Our model assumes that \begin{document}$ f(R,G) $\end{document} is an exponential function of G combined with a linear combination of R. We scrutinize the observational limitations under a power law cosmology that relies on two parameters, the Hubble constant (\begin{document}$ H_0 $\end{document}) and the deceleration parameter (q) utilizing the 57-point \begin{document}$ H(z) $\end{document} data, 8-point BAO data, 1701-point Pantheon+ data, joint data of \begin{document}$ H(z) $\end{document} + Pantheon, and joint data of \begin{document}$ H(z) $\end{document} + BAO + Pantheon+. The outcomes for \begin{document}$ H_0 $\end{document} and q are realistic within observational ranges. We also address energy conditions, \begin{document}$ Om(z) $\end{document} analysis, and cosmographical parameters such as jerk, lerk, and snap. Our estimate of \begin{document}$ H_0 $\end{document} is remarkably consistent with various recent Planck Collaboration studies that utilize the ΛCDM model. According to our study, power law cosmology within the context of \begin{document}$ f(R,G) $\end{document} gravity provides the most comprehensive explanation of the important aspects of cosmic evolution.
Critical collapse in asymptotically anti-de Sitter spacetime
Li-Jie Xin, Cheng-Gang Shao
2025, 49(4): 045103. doi: 10.1088/1674-1137/ada378
Abstract:
We investigate the critical collapse of spherically symmetric scalar fields in asymptotically anti-de Sitter spacetime, focusing on two scenarios: real and complex scalar fields with potentials. By fine-tuning the amplitude of the initial scalar field under different cosmological constants, we find a linear relationship between the critical amplitude of the first collapse and the cosmological constant in both scenarios. Furthermore, we observe that the slope of this linear relationship varies linearly with coupling strength.
Shadow and gravitational weak lensing around a quantum-corrected black hole surrounded by plasma
Mirzabek Alloqulov, Yokubjon Isaqjonov, Sanjar Shaymatov, Abdul Jawad
2025, 49(4): 045104. doi: 10.1088/1674-1137/ad9f44
Abstract:
In this study, we investigate the optical properties of a quantum-corrected black hole (BH) in loop quantum gravity surrounded by a plasma medium. First, we determine the photon and shadow radii resulting from quantum corrections and the plasma medium in the environment surrounding a quantum-corrected BH. Our findings indicate that the photon sphere and BH shadow radii decrease owing to the quantum correction parameter α, which acts as a repulsive gravitational charge. Further, we investigate the gravitational weak lensing by applying the general formalism used to model the deflection angle of the light traveling around the quantum-corrected BH within the plasma medium. We show, in conjunction with the fact that the combined effects of the quantum correction and non-uniform plasma frequency parameter can decrease the deflection angle, that the light traveling through the uniform plasma can be strongly deflected than the non-uniform plasma environment surrounding the quantum-corrected BH. Finally, we examine the magnification of the lensed image brightness under the effect of the quantum correction parameter α, including the uniform and non-uniform plasma effects.
Fixing the AdS3 metric from pure state entanglement entropies of CFT2
Peng Wang, Houwen Wu, Haitang Yang
2025, 49(4): 045105. doi: 10.1088/1674-1137/ada960
Abstract:
In this study, based on the Ryu-Takayanagi formula, by identifying the pure state UV and IR entanglement entropies of a perturbed CFT2 with geodesic lengths in the bulk, we demonstrate that the dual geometry is uniquely determined to be asymptotically AdS3. The pure AdS3 geometry is recovered by taking the massless limit of the system. Our derivations hold in both static and covariant scenarios.
Inferring a spinning black hole in an expanding universe via the S2 star around the galactic center
Jin-Tao Yao, Xin Li
2025, 49(4): 045106. doi: 10.1088/1674-1137/ad9304
Abstract:
The nearest black hole to Earth, Sagittarius A\begin{document}$ ^\star $\end{document} (Sgr A\begin{document}$ ^\star $\end{document}), with its intense gravitational field, provides a unique opportunity to explore black hole mysteries. Over the past few decades, monitoring of the S2 star has provided extensive valuable data that can be utilized to examine various gravity theories and black hole paradigms. This paper focuses on the most intriguing objects in astronomy, spinning black holes, and investigates the effects of spin on orbital motion. By applying the Markov Chain Monte Carlo algorithm to publicly available observational data of the S2 star, our findings indicate that current data fail to constrain the spin of Sgr A\begin{document}$ ^\star $\end{document}. Simulated stars with smaller semi-major axes reveal that the direction of Lense-Thirring precession aligns with the spin direction of Sgr A\begin{document}$ ^\star $\end{document}. Additionally, by incorporating the cosmological constant, which accounts for the expansion of the universe, into our analysis, we establish an upper limit of \begin{document}$ \Lambda \lesssim 7.3 \times 10^{-34} \text{ km}^{-2} $\end{document} on the cosmological constant at the \begin{document}$ 1\sigma $\end{document} confidence level. Future long-term monitoring of S-cluster stars, combined with enhanced observational precision, may enable the determination of the spin of Sgr A\begin{document}$ ^\star $\end{document} and further tighten the bound on the cosmological constant.
Geometric constraints via Page curves: insights from island rule and quantum focusing conjecture
Ming-Hui Yu, Xian-Hui Ge
2025, 49(4): 045107. doi: 10.1088/1674-1137/ada34e
Abstract:
To explore the inverse problem tied to the Page curve phenomenon and island paradigm, we investigate the geometric conditions underpinning black hole evaporation, where information is preserved and islands manifest, giving rise to the characteristic Page curve. Focusing on a broad class of static spherical symmetry black hole metrics in asymptotically Minkowski or (anti-)de Sitter spacetimes, we derive a pivotal constraint, the second derivative of the blacken factor \begin{document}$ f^{\prime \prime}(r_h)<\frac{6 \kappa A^{\prime}(r_h)}{cG_N} $\end{document} for which the island exists, and reproduce the Page curve. Moreover, starting from the quantum focusing conjecture theory, we obtain another constraint on the blacken factor for which the theory can be satisfied: \begin{document}$f^{\prime \prime}(r_h) < \frac{6 \kappa^2 r_h A^{\prime}(r_h) {\rm e}^{2\kappa r_{\star}(b)} }{cG_N f(b)}$\end{document}. In particular, by studying these two constraints, we find common properties. Specifically, we reveal that a universal criterion, manifested in the negativity of the second derivative of \begin{document}$ f(r) $\end{document}, i.e., \begin{document}$ f^{\prime \prime} (r)<0 $\end{document}, in proximity to the event horizon where \begin{document}$ r \sim r_h+ {\cal O} (G_N) $\end{document}, ensures the emergence of Page curves and follows the quantum focusing conjecture in a manner transcending specific theoretical models. Finally, we argue that the negativity of the second derivative of the blacken factor \begin{document}$ f(r) $\end{document} near the event horizon strongly indicates negative heat capacity, which implies that black holes with a negative heat capacity must have islands and satisfy the quantum focusing conjecture.
Friedmann’s universe controlled by Gauss-Bonnet modified gravity
F. dos Anjos, M. Novello
2025, 49(4): 045108. doi: 10.1088/1674-1137/ad9b9e
Abstract:
We consider a Lagrangian to describe gravity using a nonlinear term depending on the Gauss-Bonnet topological invariant. We examine the conditions for a bouncing and the existence of an ulterior accelerated phase of the universe. The original concept of Einstein's first paper on cosmology was to modify the equations that control the gravitational metric. Based on this, several authors have proposed different formalisms to modify general relativity. Herein, a function of the topological invariant is used in a homogeneous and isotropic cosmological model. First, a case with the topological invariant as a constant is thoroughly examined, yielding specific constraints on the evolution of the Hubble parameter. Subsequently, we study a function of the topological invariant squared. In an empty space-time scenario, the term that modifies Einstein’s equations functions as an effective geometrical density, and we map regions in the phase space in which the effective pressure is positive or negative. This results in non-trivial integral solutions such as cyclic stages of acceleration and deceleration of the scale factor in the model, among other behaviors. We add cosmic dust to the system, and for certain classes of solutions, we observe that the minimum positive value of the Hubble parameter is limited by the cosmic dust matter density. If this matter density reaches zero, the minimum value of the Hubble parameter also reaches zero.
Precisely constraining the properties of neutron stars using new universal relations and astronomical observations
Zehan Wu, Dehua Wen
2025, 49(4): 045109. doi: 10.1088/1674-1137/ad9301
Abstract:
Given the significant uncertainty in the equation of state (EOS) of high-density nuclear matter, establishing EOS-independent universal relations between global properties of neutron stars provides a practical method to constraining unobservable or difficult-to-observe properties using astronomical observations. Constructing universal relations between EOS-dependent properties (e.g., moment of inertia, tidal deformation, etc.) or combined properties (e.g., compactness) is common, and improving the precision of the universal relations may provide stricter constraint on the properties of neutron star. We find that in 3-dimensional space with mass and radius as the base coordinates, the points corresponding to properties of a neutron star described by different EOSs are almost located on the same surface. Thus, the universal relation between the property and the stellar mass-radius can be expressed through describing the surface. We demonstrate that the resulting universal relations have greater precision. For example, we construct high-precision universal relations for the moment of inertia, the f-mode frequency, and the dimensionless tidal deformation with respect to the mass-radius. With the increase in the size and accuracy of NICER observational data for neutron star masses and radii, these universal relations allow for more precise constraints on the unobservable or difficult-to-observe properties.
Observational signatures of traversable wormholes
Yiqian Chen, Lang Cheng, Peng Wang, Haitang Yang
2025, 49(4): 045110. doi: 10.1088/1674-1137/adb414
Abstract:
This study investigates the observational signatures of traversable Simpson-Visser wormholes illuminated by luminous celestial spheres and orbiting hot spots. We demonstrate that when light sources and observers are on the same side of a wormhole, the images of the wormhole mimic those of a black hole. However, when the light source is positioned opposite the observer, photons traversing the wormhole throat generate distinct observational signatures. Specifically, unlike black hole images, wormhole images are confined in a critical curve, resulting in smaller centroid variations. Furthermore, the light curve of hot spots can exhibit additional peaks.
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