Chinese Physics C

Observational Constraints on Dissipative Chaplygin Gas Cosmology in the Framework of Coincident f(Q) Gravity

Sayantan Ghosh, Raja Solanki, P.K. Sahoo

Published: , doi: 10.1088/1674-1137/ae50e5

Abstract:
In this current work, we shed light on the unified approach to both dark energy and dark matter via the generalized Chaplygin gas model in symmetric teleparallel gravity (STGR). We have employed the equation of state provided by the generalized Chaplygin gas, which naturally arises in string theory, tachyonic field theory, and Randall-Sundrum type brane world solutions. We show that such a generalized Chaplygin gas can not only provide a lucrative candidate for dark energy but also a viable candidate for dark matter via Bose-Einstein Condensation (BEC). We have also taken into account the interaction between dark matter and dark energy to provide a more realistic perspective. We performed MCMC analysis with combined Hubble and Pantheon data sets. We have also performed the Om diagnostics and the

\begin{document}$ r-s $\end{document}

plot to comment on the late behavior of our model. We have also found that through Om diagnostics, the values are in Phantom regions, and we have given physical reasons why this is expected. Finally, we outline some future directions for our work to be carried out.

Exploring muonphilic dark matter with the Z₂-even mediator at muon colliders

Wanyun Chen, Haoqi Li, Chih-Ting Lu, Qiulei Wang

Published: , doi: 10.1088/1674-1137/ae5044

Abstract:
The Galactic Center GeV Excess (GCE) remains a compelling but enigmatic signal from the inner region of our galaxy. Muonphilic dark matter (DM), which couples exclusively to muons via a new mediator, provides a viable explanation for the GCE and relic density while naturally evading constraints from direct detection, collider searches and other multi-messenger observations. Based on the viable non-resonant parameter space identified in previous global fits, we perform a comprehensive study exploring the prospects for discovering such muonphilic DM in the context of a future 3 TeV muon collider, focusing on simplified models with a

\begin{document}$Z_2$\end{document}

-even mediator. Four distinct search strategies are investigated: visible on-shell mediator decays (

\begin{document}$\mu^{+}\mu^{-}\gamma$\end{document}

final state), invisible on-shell mediator decays (mono-photon plus missing energy), mono-photon production via off-shell mediators, and vector boson fusion production.Through a detailed signal-background analysis using cut-and-count methods, we project the exclusion limits at

\begin{document}$ 95 $\end{document}

% confidence level for seven representative models across a wide range of mediator masses. Our results demonstrate that the projected limits cover a significant portion of the viable parameter space that explains the GCE, establishing a muon collider as a decisive machine for testing the muonphilic DM hypothesis.

Structure of the β-Decay Strength Function

I.N. Izosimov

Published:

Abstract:
An analysis of experimental data on measurements of the resonant and fine structure of the β-decay strength function

\begin{document}$S_{\beta}(E)$\end{document}

in spherical, transitional, deformed, and halo nuclei has been conducted. Modern nuclear spectroscopy methods have revealed peak splitting in

\begin{document}$S_{\beta}(E)$\end{document}

for Gamow–Teller (GT) type β-transitions, caused by nuclear deformation. The resonant structure of

\begin{document}$S_{\beta}(E)$\end{document}

for first-forbidden (FF) β-transitions has been experimentally confirmed in both spherical and deformed nuclei. It is shown that at certain nuclear excitation energies, FF β-transitions can reach intensities comparable to those of GT β-transitions. An analysis of the evolution of the energy difference (

\begin{document}$E_{\text {GTR}}{-}E_{\text {IAR}})$\end{document}

between the Gamow–Teller resonance (GTR) and the isobaric analogue resonance (IAR) with increasing neutron excess in nuclei has been performed. A region exhibiting Wigner spin–isospin

\begin{document}$SU(4)$\end{document}

symmetry has been predicted.

Cosmological Perturbation in New General Relativity: Propagating mode from the violation of local Lorentz invariance

Kyosuke Tomonari, Taishi Katsuragawa, Shin'ichi Nojiri

Published: , doi: 10.1088/1674-1137/ae4dd8

Abstract:
We investigate the propagating modes of New General Relativity (NGR) in second-order linear perturbations in the Lagrangian density (first-order in field equations). The Dirac-Bergmann analysis has revealed a violation of local Lorentz invariance in NGR. We review the recent status of NGR, considering the results of its Dirac-Bergmann analysis. We then reconsider the vierbein perturbation framework and identify the origin of each perturbation field in the vierbein field components. This identification is mandatory for adequately fixing gauges while guaranteeing consistency with the invariance ensured by the Dirac-Bergmann analysis. We find that the spatially flat gauge is adequate for analyzing a theory with the violation of local Lorentz invariance. Based on the established vierbein perturbative framework, introducing a real scalar field as matter, we perform a second-order perturbative analysis of NGR with respect to tensor, scalar, pseudo-scalar, and vector and pseudo-vector modes. We reveal the possible propagating modes of each type of NGR. In particular, we find that Type 3 has stable five propagating modes, i.e., tensor, scalar, and vector modes, compared to five non-linear degrees of freedom, which results in its Dirac-Bergmann analysis; The linear perturbation theory of Type 3 is preferable for applications to cosmology. Finally, we discuss our results in comparison to previous related work and conclude this study.

Update analysis of $ \psi(3686)\to p\bar{p}$

Zhi Gao, Rong-Gang Ping, Minggang Zhao

Published: , doi: 10.1088/1674-1137/ae4a0c

Abstract:
We present an updated analysis of the angular distribution for

\begin{document}$ \psi(3686) \to p\bar{p} $\end{document}

decay, taking into account transverse beam polarization, to investigate potential sources of forward-backward asymmetry and azimuthal modulation beyond the simple

\begin{document}$ 1+\alpha\cos^2\theta $\end{document}

form. We focus on the interference between the

\begin{document}$ \psi(3686) $\end{document}

resonance and the two-photon exchange continuum process, as well as the background from initial-state–final-state radiation interference. A maximum-likelihood fit to the

\begin{document}$ \cos\theta $\end{document}

distribution of

\begin{document}$ \psi(3686)\to p\bar{p} $\end{document}

yields

\begin{document}$ \alpha = 1.00 \pm 0.03 $\end{document}

, consistent with previous results. The fitted contributions from the two-photon interference are small but non-negligible, while the ISR–FSR background is negligible. Our model predicts a significant

\begin{document}$ \sin(2\phi) $\end{document}

modulation in the azimuthal angle, indicating the influence of transverse beam polarization. These findings motivate future two-dimensional angular analyses to fully disentangle the polarization and interference dynamics in charmonium decays to baryon pairs.

Next-to-Leading-Order QCD Predictions for the Σ Dirac Form Factors

Bo-Xuan Shi, Hui-Xin Yu, Xue-Chen Zhao

Published:

Abstract:
In this work, we compute the next-to-leading-order QCD corrections to the Dirac electromagnetic form factors of the Σ hyperons within the hard-collinear factorization framework at leading power. The corresponding short-distance coefficient functions are extracted from the relevant seven-point partonic correlation functions. We find that the one-loop radiative corrections to the leading-twist hard-scattering contributions are numerically significant over a broad range of momentum transfer. Combining the perturbatively calculated hard kernels with nonperturbative Σ distribution amplitudes determined from lattice QCD, we present state-of-the-art theoretical predictions for the Σ hyperon electromagnetic form factors.

NLO QCD sum rules analysis of 1⁻⁺ tetraquark states

Wei-Yang Lai, Hong-Ying Jin

Published:

Abstract:
We performed a next-to-leading-order (NLO) QCD sum rules analysis of the

\begin{document}$1^{-+}$\end{document}

light tetraquark states. By investigating various compact and molecular tetraquark currents, we extracted the mass spectra of the corresponding states, all of which lie above

\begin{document}$1.7\,\text{GeV}$\end{document}

. We find multiple

\begin{document}$1^{-+}$\end{document}

states around

\begin{document}$2.0\,\text{GeV}$\end{document}

that match well with

\begin{document}$\pi_{1}(2015)$\end{document}

, which makes us confident that

\begin{document}$\pi_{1}(2015)$\end{document}

is an excellent tetraquark candidate. In contrast, our calculations exclude the possibility that the

\begin{document}$\pi_{1}(1400)$\end{document}

is a tetraquark or hybrid-tetraquark mixture. This suggests that it may not exist, which is consistent with recent experimental results.

A critical investigation of γ-heating rates in stellar matter

Musarat Abbas, Jameel-Un Nabi, Arslan Mehmood

Published:

Abstract:
The simulation of observed properties of type I X-ray bursts, also known as superbursts, poses challenges once we include Cooper pair neutrinoemission from the crust of the neutron star. An additional heating of theaccumulating fuel layer is in order. γ-emission due to electron captures to excited states in astrophysical environments is a major source to make up for the heat loss carried away by the weak-interaction neutrinos. γ-heating is believed to have a significant impact during the presupernova evolution of massive stars and calculation of the thermal structure in the crust and core of a superbursts. This deposition of energy enhances entropy production and promotes convection at this stage of stellar evolution. Effective γ-heating rates may contribute to reduction of the ignition depth of superbursts. A recent investigation ranked the leading electron capturing nuclei causing significant changes in the lepton-to-baryon fraction (

\begin{document}$Y_e$\end{document}

) of the stellar matter after silicon core burning. We investigate γ-heating rates from the excited states of the top 100 electron capture and positron decay nuclei identified in recently published ranking list. To assess the influence of γ-heating rates, each nucleus was analyzed using four different empirical pairing gaps and three distinct sets of nuclear deformation parameters. We report our calculations for the temperature range [(1 - 10) GK] and density range [(

\begin{document}$10^{9}$\end{document}

-

\begin{document}$10^{11}$\end{document}

) g/cm

\begin{document}$^{3}$\end{document}

]. The calculated γ-heating rates changed up to a factor 26 (16) with changing deformation values (pairing gaps). Our findings may contribute to a more realistic simulations of post-silicon burning phases of massive stars and superbursting neutron stars.

Systematic study of proton radioactivity based on the double-folding potential model

Hai-Tao Yang, Zhong-Xia Zhao, Xiao-Pan Li, Yu-Hui Luo, Xun Xue, Xiao-Jun Bao

Published:

Abstract:
We study proton radioactivity in proton-rich nuclei with

\begin{document}$ 53 \le Z \le 83 $\end{document}

within a semi-microscopic framework in which the emitted proton is described by a finite-size density distribution. Two proton-density prescriptions are considered, namely a Gaussian profile and a Fermi profile. We find that, when microscopic spectroscopic factors are combined with a double-folding potential based on finite-size proton and daughter densities, the Fermi-density prescription yields the best overall agreement with experiment, reducing the global root-mean-square (RMS) deviation of

\begin{document}$ \log_{10} T_{1/2} $\end{document}

to

\begin{document}$ \sigma = 0.37 $\end{document}

. In addition, a modified universal decay law that embeds the same spectroscopic factors yields an even smaller deviation,

\begin{document}$ \sigma = 0.28 $\end{document}

, thereby providing a high-precision global description of proton-radioactivity half-lives. Specifically, we construct the proton–daughter interaction by folding a Skyrme-type effective nucleon–nucleon interaction with finite-size proton densities and spherical daughter densities, and we evaluate proton-emission half-lives within the Wentzel–Kramers–Brillouin (WKB) approximation for 39 known proton emitters in this region. State-dependent spectroscopic factors

\begin{document}$ S_p^{{\rm{QYB}}} $\end{document}

and

\begin{document}$ S_p^{{\rm{ZHF}}} $\end{document}

, obtained from relativistic mean-field plus Bardeen–Cooper–Schrieffer (RMF+BCS) calculations, are employed to account for proton preformation. We then confront the calculated half-lives with experimental data and analyze the residuals by grouping them according to the minimum orbital angular momentum and whether the decay proceeds from the ground state or an isomeric state. Finally, we extend the universal decay law for proton emission (UDLP) by including an explicit spectroscopic-factor term, thereby obtaining a modified formula (MUDLP) that provides a compact global parametrization of experimental proton-radioactivity half-lives. Using the best-performing semi-microscopic prescription together with the MUDLP parametrization, we provide conditional half-life estimates for several candidate proton emitters near the proton drip line, where the input

\begin{document}$ Q_{p} $\end{document}

values are taken from AME2020. These results provide quantitative reference values for future experimental searches for new proton-radioactive nuclei.

Quantum Gravitational Corrections to Reissner-Nordström Black Hole Thermodynamics and Their Implications for the Weak Gravity Conjecture

Yong Xiao, Qiang Wang, Aonan Zhang

Published: , doi: 10.1088/1674-1137/ae457a

Abstract:
In this paper, we investigate the quantum gravitational corrections to the thermodynamical quantities of Reissner-Nordstr?m black holes within the framework of effective field theory. The effective action originates from integrating out massless particles, including gravitons, at the one-loop level. We perform a complete thermodynamic analysis for both non-extremal and extremal black holes and are mainly concerned with the shift in the charge-to-mass ratio

\begin{document}$ q/M$\end{document}

, which plays an important role in analyzing the weak gravity conjecture. For non-extremal black holes, we identify a relationship between the shift in the charge-to-mass ratio and the thermodynamic stability of the black holes. For extremal black holes, we show that quantum gravity effects naturally lead to the super-extremality

\begin{document}$ q/M>1$\end{document}

of charged black holes.

Studies on quark-mass dependence of the N^*(920) pole from unitarized πN χPT amplitudes

Xu Wang, Kai-Ge Kang, Qu-Zhi Li, Zhiguang Xiao, Han-Qing Zheng

Published:

Abstract:
The quark-mass dependence of the

\begin{document}$ N^*(920) $\end{document}

pole is analyzed using K-matrix method, with the

\begin{document}$ \pi N $\end{document}

scattering amplitude calculated up to

\begin{document}$ O(p^3) $\end{document}

order in chiral perturbation theory. As the quark mass increases, the

\begin{document}$ N^*(920) $\end{document}

pole gradually approaches the real axis in the complex w-plane (where

\begin{document}$ w=\sqrt{s} $\end{document}

). Eventually, in the

\begin{document}$ O(p^2) $\end{document}

case, it crosses the u-cut on the real axis and enters the adjacent Riemann sheet when the pion mass reaches

\begin{document}$ 526\; {\rm{MeV}} $\end{document}

. At order

\begin{document}$ O(p^3) $\end{document}

, the rate at which it approaches the real axis slows down; however, it remains uncertain whether it will ultimately cross the u-cut and enter the adjacent Riemann sheet. Additionally, the trajectory of the

\begin{document}$N^*(920)$\end{document}

pole is in qualitative agreement with the results from the linear σ model calculation.

Lepton flavor of four-fermion operator and fermion portal dark matter

Yuxuan He, Gang Li, Jia Liu, Xiao-Ping Wang, Xiang Zhao

Published:

Abstract:
We study the ultraviolet realization of semileptonic four-fermion operator

\begin{document}$ O_{ledq}^{\alpha \beta 11} $\end{document}

that incorporates Majorana dark matter (DM) in both lepton-flavor-conserving (LFC) and lepton-flavor-violating (LFV) scenarios at the one-loop level via box diagram, which effectively alleviates the lower bounds on the new physics scale. The interplay between the model-independent constraints on the Wilson coefficients and DM direct detection, relic density, and collider searches in the context of fermion portal DM model with two mediators is investigated. We find that both the projected future constraint on the LFC Wilson coefficient

\begin{document}$ C_{ledq}^{2211}/\Lambda^2< (12.3\; \text{TeV})^{-2} $\end{document}

from the measurements of neutrino non-standard interaction in the next-generation neutrino oscillation experiments, and LFV constraint

\begin{document}$ C_{ledq}^{1211}/\Lambda^2< \left(2.2\times 10^3\; \text{TeV} \right)^{-2} $\end{document}

from ongoing charged-lepton-flavor-violation searches, provide a complementary exploration of the parameter space encompassing the DM mass and scalar mass. With the colored mediator mass typically around

\begin{document}$ 2\; \text{TeV} $\end{document}

, the sensitivity of the indirect constraints on the four-fermion operator could surpass those of collider searches and DM direct detection, in scenarios where the masses of the DM and scalar are close. By ensuring the correct DM relic density, however, we obtain that the collider searches and DM direct detection are more sensitive to the electroweak scale DM and scalar compared to the indirect constraints.

Higgs Decays to Zγ and γγ in the Flavor-Gauged Two Higgs Doublet Model

Feng-Zhi Chen, Qiaoyi Wen, Fanrong Xu

Published:

Abstract:
This work examines the

\begin{document}$ h\to Z\gamma $\end{document}

and

\begin{document}$ h\to\gamma\gamma $\end{document}

decays in the flavor-gauged two Higgs doublet model (FG2HDM), which augments the Standard Model (SM) with an additional scalar doublet, a singlet, and a

\begin{document}$ U(1)' $\end{document}

flavor gauge symmetry. Beyond the SM spectrum, the FG2HDM predicts five additional physical scalars and a new neutral gauge boson,

\begin{document}$ Z' $\end{document}

. We demonstrate that while both decay channels are sensitive to charged Higgs loops,

\begin{document}$ h \to Z\gamma $\end{document}

is uniquely modified by fermion-antifermion-Z (

\begin{document}$ f\bar{f}Z $\end{document}

) vertex corrections. These vertex corrections further impact top-quark observables and the flavor-changing neutral current (FCNC) process

\begin{document}$ b\to s\ell^+\ell^- $\end{document}

. Our analysis identifies a viable parameter space (

\begin{document}$ m_{H^\pm}>200 $\end{document}

GeV and

\begin{document}$ \lambda_{hH^+H^-}<0 $\end{document}

) consistent with current

\begin{document}$ 1\sigma $\end{document}

experimental limits, where the signal strength

\begin{document}$ \mu_{\gamma\gamma} $\end{document}

remains the primary constraint on scalar sector parameters. Regarding the

\begin{document}$ f\bar{f}Z $\end{document}

couplings, we delineate the allowed regions in the

\begin{document}$ \mathcal{Q}_{tL} $\end{document}

-

\begin{document}$ \mathcal{Q}_{tR} $\end{document}

plane by evaluating the leading top-quark contributions, revealing that

\begin{document}$ b\to s\ell^+\ell^- $\end{document}

imposes the most stringent bounds. Finally, we highlight that the

\begin{document}$ 14\% $\end{document}

projected precision for

\begin{document}$ \mu_{Z\gamma} $\end{document}

at the High-Luminosity LHC (HL-LHC) will significantly enhance the sensitivity to the FG2HDM.

Improved Geiger-Nuttall law for one-proton and two-proton radioactivity

Zhipeng Han, Niu Wan

Published:

Abstract:
Proton radioactivity, a rare decay mode occurring in proton-rich nuclei beyond the proton drip line, provides valuable insights into nuclear structure, nuclear stability, and the limits of nuclear existence. Building upon the Geiger–Nuttall (GN) law and recent developments in one-proton and two-proton radioactivity systematics, this work proposes an improved GN law that explicitly separates the effects of the daughter-nucleus charge

\begin{document}$Z_d$\end{document}

and the orbital angular momentum l. Previous empirical formulas typically couple or add these two contributions, despite their fundamentally different physical origins—the long-range Coulomb interaction and the relatively shorter-range centrifugal potential. By introducing an additional parameter to independently scale the l-dependent contribution, we quantify their separate roles on the decay half-life. Using experimental data from 44 proton emitters and available two-proton emitters, we determine the optimal parameter sets for both one-proton and two-proton radioactivity. The improved GN law yields a smaller standard deviation σ=0.357 for one-proton emission and reproduces experimental two-proton radioactive half-lives within one order of magnitude. The resulting law provides enhanced predictive power and a physically transparent interpretation of Coulomb and centrifugal contributions, offering reliable theoretical support for future studies and experimental searches of exotic proton-rich nuclei.

Assessing the impact of the electron ion collider in China on Deeply Virtual Compton Scattering

Yuan-Yuan Huang, Xu Cao, Taifu Feng, Krešimir Kumerički, Yu Lu

Published:

Abstract:
We assess the impact of future measurements of deeply virtual Compton scattering (DVCS) off protons using the planned detector at the Electron-Ion Collider in China (EicC), proposed as an upgrade to the High Intensity heavy-ion Accelerator Facility (HIAF). We develop a neural-network architecture to flexibly parameterize the Compton Form Factors (CFFs), extrapolate reliably into unmeasured kinematic regions, and provide robust uncertainty estimates through the replica method. The framework is fitted to the available worldwide DVCS data using the

\begin{document}$ {\mathrm{Gepard}}$\end{document}

software. We find a significant reduction in the uncertainties of all CFFs after incorporating pseudo-data from single and double polarization asymmetries at the EicC, with particularly strong improvements in the sea-quark region.

Negative potential-induced scalarization in the Einstein-Euler-Heisenberg black hole

Hong Guo, Miok Park, Yun Soo Myung

Published:

Abstract:
We investigate a negative potential-induced scalarization of the Einstein-Euler-Heisenberg (EEH) black hole in the EEH-scalar theory, characterized by mass M, Euler-Heisenberg parameter μ and magnetic charge q. In the regime

\begin{document}$ \mu>\mu_{{\rm{max}}} = 0.019 $\end{document}

(with

\begin{document}$ M=1/2 $\end{document}

), the black hole admits a single horizon and allows for overcharged configurations with

\begin{document}$ q/M \gt 1 $\end{document}

. We obtain a single branch of scalarized EEH (sEEH) black holes for

\begin{document}$ q>0 $\end{document}

which is considered as the simplest model for scalarization of EEH black holes. We find that this class of hairy black holes is not thermodynamically favored, and their quasinormal modes indicate they are dynamically unstable. An notable feature is that the scalar charge depends weakly on q for

\begin{document}$ q<1/2 $\end{document}

, but grows more rapidly for

\begin{document}$ q>1/2 $\end{document}

, suggesting a transition from primary- to secondary-type scalar charge. This finding reveals characteristic properties of hairy black holes in EEH theory, specifically in the overcharging regime.

Reinvestigating the Level Structure of ⁹⁵Mo: Coexistence of Single-Particle Excitations and Collective Motions

S. Y. Guo, R. Guo, J. B. Lu, B. Ding, D. Chen, H. Y. Ye, Z. Ren, J. Li, K. Y. Ma, S. Guo, M. L. Liu, K. K. Zheng, G. S. Li, J. G. Wang, Y. H. Qiang, Y. D. Fang, M. Y. Liu, W. Q. Zhang, F. F. Zeng, H. Huang, Q. B. Zeng, Y. Zheng, T. X. Li, S. Y. Wang, C. Liu, X. C. Han, X. Xiao, L. Mu, W. Z. Xu, H. F. Bai, Y. J. Li, X. D. Wang, L. Zhu, Y. H. Wu

Published:

Abstract:
Excited states of ⁹⁵Mo have been reinvestigated via the ⁸⁷Rb(¹²C,1p3n)⁹⁵Mo fusion-evaporation reaction at a beam energy of 62 MeV. The level scheme of ⁹⁵Mo was enriched by the addition of 13 γ-ray transitions and 11 new levels, while the placements of 6 transitions were reassigned. Shell-model calculations with the GWBXG and SNET interactions were performed to reproduce parts of the observed level structure, providing relevant configuration information. Furthermore, a systematic analysis of the low-lying positive-parity yrast states was conducted for ⁹⁵Mo and its neighboring

\begin{document}$ N=53 $\end{document}

isotones. In addition, three-dimensional tilted axis cranking covariant density functional theory (3DTAC-CDFT) calculations indicate a weakly prolate deformation for ⁹⁵Mo. Combined with systematics, it suggests that collectivity similar to that in neighboring nuclei such as ^97,99,101Mo may be presented in ⁹⁵Mo.

Massive U(1) gauge fields and their accompanying scalars in brane world

Ye-Hao Yang, Wen-Xuan Ma, Chun-E Fu

Published:

Abstract:
In brane-world scenarios, the effective action of a massless bulk

\begin{document}$U(1)$\end{document}

gauge field preserves gauge invariance via couplings between massive vector Kaluza-Klein (KK) modes and scalar KK modes. In this work, we extend this framework by introducing a term

\begin{document}$(\nabla^M X_M)^2$\end{document}

into the massless bulk

\begin{document}$U(1)$\end{document}

gauge action. This modification explicitly breaks the full gauge redundancy while preserving a residual gauge symmetry both in the bulk and on the brane. In this setup, the scalar KK modes can acquire masses from the background geometry. Notably, we find that on the 5D brane, these scalar KK modes are lighter than the vector KK modes. In contrast, on the 6D brane, two types of scalar modes emerge; the mixed interactions between them give rise to oscillations among these scalar modes.

The HADAR Project Based on Fresnel Lenses, Part I: Optical Simulation Study of the Telescope Unit

Mei-Lin Liu, Guo-Qiang Zhang, Qi-Ling Chen, Yu-Fan Fan, Yu-Jie Cai, Yong-Liang Wang, Ming-Ming Kang, Qi Gao, Tian-Lu Chen, Yi-Qing Guo, Cheng Liu, Mao-Yuan Liu, Dan-Zeng Luo-Bu, Guang-Guang Xin, Jie He

Published:

Abstract:
The High Altitude Detection of Astronomical Radiation (HADAR) project proposes the use of a refracting telescope composed of four 5.0 m diameter water lenses arranged in a square configuration (100 m × 100 m), featuring a wide field of view (FoV, up to 0.84 sr) and low-energy threshold characteristics, to observe Cherenkov light generated by high-energy cosmic rays in atmospheric air showers. The Fresnel lens exhibits excellent imaging performance, lightweight characteristics, mature manufacturing processes, strong adaptability in high-altitude low-temperature environments, and facilitates array deployment. It has been engineering-validated through a series of pilot missions in the JEM-EUSO program, leading to the proposal of a telescope unit design that utilizes the Fresnel lens as an alternative to the water lens. This paper simulates and examines the influence of parameters such as the radius of curvature, tooth width, and thickness of the Fresnel lens on the focal length and image spot (

\begin{document}$r_{80}$\end{document}

). Five Fresnel lenses with the same focal length as the 5.0 m diameter water lens are designed. The best focusing positions under different incident angles were extracted, and the curved image surface was constructed through fitting. The results show that the imaging quality of the Fresnel lens mainly depends on the radius of curvature. As the focal length increases,

\begin{document}$r_{80}$\end{document}

gradually decreases until it remains unchanged. The tooth width and thickness of the lens mainly affect the structural complexity of the lens and have little impact on the imaging quality. The curved image surface design can effectively suppress the aberrations and changes in solid angle caused by increased incidence angles, thereby maintaining the acceptance approximately consistent across different incidence angles. To meet the scientific objectives (wide FoV, low-energy threshold) consistent with HADAR and take into account engineering constraints (focal length

\begin{document}$\leq$\end{document}

10 m) in this paper, we select a Fresnel lens with a diameter of 2.0 m and a focal length of 5.3 m (FoV angle 29°, total acceptance 9.81 m²·sr) as the basic lens unit for subsequent array performance simulation, based on the premise that the total acceptance is not lower than that of the water lens unit (7.43 m²·sr), the on-axis imaging

\begin{document}$r_{80}$\end{document}

is less than 7.5 cm, and the FoV is as wide as possible.

Analytical Study of Fundamental Oscillation Frequencies Around Black Holes in Non-Local Gravity

Rana Muhammad Zulqarnain, Phongpichit Channuie, Abdelmalek Bouzenada, Asifa Ashraf, Farruh Atamurotov, Ikhtiyor Saidov

Published:

Abstract:
In this study, we investigate the dynamics of test particles in the spacetime of a static, spherically symmetric black hole (BH), illustrated within the non-local gravity models. In this case, after presenting the BH geometries and horizon structures, we examine the motion of particles by analyzing the effective potential, the innermost stable circular orbits (ISCOs), and the corresponding effective force. Also, we then extend the study to small perturbations of circular orbits, exploring harmonic oscillations characterized by the frequencies measured both by local observers and by distant ones, as well as the periastron precession effects. Particular attention is devoted to the interplay between the non-local gravity corrections and the stability properties of geodesics. In this case, we analyze the center-of-mass energy (CME) of colliding particles near the event horizon and show the influence of BH parameters on energy extraction processes. In this context, the results show how non-local modifications of gravity affect the standard predictions of BH structure, orbital stability, and high-energy particle dynamics, with possible implications for astrophysical observations and theoretical models of strong gravity. This study examines the differences between the inverse electrodynamics BH and the Schwarzschild BH configuration, showing how additional parameters influence the dynamics and stability of the test particles.

Exploring toroidal α-cluster configurations in ²⁸Si within the 7α cluster model

Su-Yu Zhou, Bo Zhou

Published: , doi: 10.1088/1674-1137/ae4578

Abstract:
Two

\begin{document}$ 7\alpha $\end{document}

cluster configurations in

\begin{document}$ ^{28}\mathrm{Si} $\end{document}

—a uniform toroidal configuration and a disk-like configuration—are investigated within the framework of the generator coordinate method (GCM) with Brink-Bloch 7α wave functions by taking the edge length as the generator coordinate. Within the framework of the 7α cluster model with imposed geometric symmetry, we observe that a uniform toroidal configuration may emerge at approximately 40 MeV above the 7α threshold. This provides a cluster-model perspective that complements some mean-field descriptions of toroidal structure in

\begin{document}$ ^{28}\mathrm{Si} $\end{document}

.

The role of near neutron drip-line nuclei in the r-process

Ting Yu, Yue-Ying Guo, Xiao-fei Jiang, Xin-Hui Wu

Published:

Abstract:
The role of near neutron-drip-line nuclei in the rapid neutron-capture process (r-process) is studied with the classical r-process model. Simulations under different astrophysical conditions (T,

\begin{document}$n_n$\end{document}

) show that r-process paths approach the neutron-drip line under low-temperature and high-neutron-density conditions. A sensitivity study reveals that variations in the nuclear masses of these exotic nuclei lead to obvious abundance variations in the

\begin{document}$A=110-125$\end{document}

,

\begin{document}$A=175-185$\end{document}

,

\begin{document}$A=200-205$\end{document}

, and superheavy regions. By contrast, the r-process rare-earth peak and the

\begin{document}$A=130,195$\end{document}

peaks remain largely unaffected. The nuclei that obviously impact r-process abundances are mainly distributed in the region of

\begin{document}$25\leq Z\leq 90$\end{document}

and

\begin{document}$50\leq N\leq 180$\end{document}

, with the nuclei around neutron magic numbers found to be particularly important for the r-process, even in the near-neutron-drip-line region.

Investigation of the Level Structure of ⁹¹⁻⁹⁴Zr Nuclei Using Large-Scale Shell-Model Calculations

Bin-Ran Tan, Hao-Yu Jiang, H. K. Wang, Zhi-Hong Li

Published:

Abstract:
A suitable Hamiltonian is designed for the Zr isotopes over the N = 50 shell by including shell model space between ⁷⁸Ni and ¹³²Sn. The Hamiltonian is composed by the pairing-plus-multipole force and monopole correction terms. The single-particle energies (SPEs) are initially taken from the low-lying states of the hole nuclei ¹³¹In and ¹³¹Sn (near the N=82 shell closure). These SPEs are then modified by three monopole correction terms to better describe the low-lying states of ⁹¹Zr (near the N=50 shell closure). To test this Hamiltonian, the level spectra of ⁹¹⁻⁹⁴Zr are investigated in both low-lying and high-spin excitations by large-scale shell-model calculations. Their wave functions are further tested by comparing the electromagnetic transition probabilities with given

\begin{document}$ B(E2)$\end{document}

data. The good performance in both spectra and transitions probabilities makes the predicting calculations of the present interaction more dependable to be referred in further experimental researches of Zr isotopes.

Inflation Driven by Scalar-Neutrino Coupling in a Mass-Varying Neutrino Framework

Hemanshi Bundeliya, Gaurav Bhandari, S. D. Pathak, V. K. Sharma

Published:

Abstract:
We propose a cosmological framework in which neutrino masses evolve dynamically through coupling with a scalar field that simultaneously drives inflation. The neutrino mass is modeled as a power-law, exponential, or hybrid function of the scalar field, yielding an effective potential that includes neutrino backreaction. Starting from the Einstein–Hilbert action in a flat FLRW background, we derive the modified Friedmann and Klein–Gordon equations incorporating this coupling. Using the Fermi–Dirac integrals, we account for the continuous transition of neutrinos from relativistic to nonrelativistic regimes. The inflationary dynamics are investigated through the slow-roll parameters derived from the effective potential, together with the evaluation of the scalar spectral index

\begin{document}$ n_s $\end{document}

, and the tensor-to-scalar ratio r for each model. The exponential and mixed MaVaN couplings emerge as the most flexible cases, allowing inflationary dynamics and neutrino mass variation to be accommodated within a single scalar field, only in a constrained region of parameter space.

Gluon Wigner distributions with transverse polarization at non-zero skewness

Sujit Jana, Kenil Solanki, Vikash Kumar Ojha

Published:

Abstract:
We investigate the gluon Wigner distributions at non-zero skewness using light-front wave functions (LFWFs) in the dressed quark model, where the target state is a quark dressed with a gluon in the leading-order Fock space expansion. Our analysis focuses on the configurations in which the gluon, the target, or both are transversely polarized. We derive analytical expressions for the Wigner distributions in the boost-invariant longitudinal space (σ) for transversely polarized configurations and observe a diffraction-like oscillatory pattern in σ-space, analogous to that reported earlier for unpolarized and longitudinally polarized gluons.

Where Does Tracing of Cosmic Ray in Real Atmosphere Terminate?

Du-Xin Zheng, Long Chen, Ran Huo

Published:

Abstract:
In backtracing simulations, which are widely employed to determine cosmic-ray particle trajectories in the geomagnetic field, the atmosphere is typically approximated as an artificial sharp boundary at some low altitude where the traced trajectory terminates. In this paper, we extend beyond this simplified assumption and investigate two realistic physical processes that terminate cosmic-ray particle propagation in the atmosphere: Bethe-Bloch energy loss mechanisms and hard scattering interactions with atmospheric atoms using total cross sections based on the Glauber-Gribov formalism. The former mechanism dominates at low rigidities (for protons below

\begin{document}$ \sim0.57 $\end{document}

GV), while the latter becomes dominant at higher rigidities. Consequently, we introduce two dimensionless variables up to detailed numerical criteria: the relative rigidity shift due to Bethe-Bloch effects (

\begin{document}$ \Delta\mathfrak{R}/\mathfrak{R} $\end{document}

), and the expected number of hard scattering events (

\begin{document}$ \langle N\rangle $\end{document}

). Using the corrected US Standard Atmosphere 1976 model, we demonstrate that the altitude dependence can be factorized as approximately

\begin{document}$ \exp(-0.14h/ ) $\end{document}

. Additionally, the effect of the local curvature radius of the trajectory near perigee can be similarly factorized. Our calculations indicate that the simplified sharp-boundary altitude should be at least 50 km with

\begin{document}$ \Delta\mathfrak{R}/\mathfrak{R}+\langle N\rangle\lesssim1 $\end{document}

for protons, increasing by more than 15 km for heavy nuclei such as iron.

In-medium NN → N∆ cross sections from constrained relativistic mean field models

Ying Cui, Enpei Liang, Xinyu Wang, Yuan Tian, Zhuxia Li, Yingxun Zhang

Published: , doi: 10.1088/1674-1137/ae3072

Abstract:
The theoretical prediction on the the in-medium

\begin{document}$NN\rightarrow N\Delta$\end{document}

cross sections based on a one boson exchange model involves significant parameter uncertainties. In this work, we reduce these uncertainties by employing relativistic mean field (RMF) models constrained by neutron star observations. Specifically, the range of the correction factors

\begin{document}$R=\sigma^*_{NN\rightarrow N\Delta}/\sigma^{free}_{NN\rightarrow N\Delta}$\end{document}

is significantly narrowed at nuclear densities above saturation.

Multinucleon transfer products in ⁴⁸Ca, ⁵⁴Cr +²⁴³ Am and ⁵⁴Cr +²³⁸ U reactions

G. Xie, Z. Y. Zhang, J. G. Wang, L. Ma, M. H. Huang, C. L. Yang, X. L. Wu, Z. G. Gan, H. B. Yang, M. M. Zhang, Y. L. Tian, Y. S. Wang, J. Y. Wang, Y. H. Qiang, L. Zhu, X. Y. Huang, S. Y. Xu, Z. Zhao, Z. C. Li, X. Zhang, H. Zhou, J. H. Zheng, L. C. Sun, F. Guan, W. X. Huang, Z. Qin, Y. Wang, X. J. Yin, Y. F. Cui, Y. He, L. T. Sun, Z. Z. Ren, S. G. Zhou, V. K. Utyonkov, A. A. Voinov, Yu. S. Tsyganov, A. N. Polyakov, D. I. Solovyev, D. Ibadullayev, M. V. Shumeiko

Published:

Abstract:
Experiments with the ⁴⁸Ca and ⁵⁴Cr induced reactions were performed at the gas-filled recoil separator SHANS2 (Spectrometer for Heavy Atoms and Nuclear Structure-2) of the China Accelerator Facility for superheavy Elements (CAFE2). The isotopic distributions of nuclei produced in the reactions ⁴⁸Ca +²⁴³ Am, ⁵⁴Cr +²⁴³ Am, and ⁵⁴Cr +²³⁸ U were investigated. Bombardments were conducted at the energies near the respective Coulomb barriers, with the SHANS2 magnetic rigidities set to collect fusion-evaporation residues. α-decay spectroscopy was employed to identify products, revealing 58 different isotopes in these experiments. The analysis indicates that the distribution of nuclides produced in different reactions exhibits clear systematic trends. Based on their mass distributions, these nuclei were attributed to the products from the quasi-fission (QF) process. In addition, several short-lived fission events were identified and attributed to the fission isomers near the target.

Bayesian Extraction of HQET Parameters from Inclusive Semi-Leptonic Decay of the Λ_c⁺ Baryon

Dong Xiao, Kangkang Shao

Published:

Abstract:
We extract the non-perturbative Heavy Quark Effective Theory (HQET) parameters from the inclusive semi-leptonic decay

\begin{document}$ \Lambda_c^+ \to X e^+ \nu_e $\end{document}

. Unlike charmed mesons produced near threshold,

\begin{document}$ \Lambda_c^+ $\end{document}

baryons produced in

\begin{document}$ e^+e^- $\end{document}

annihilation exhibit a complex momentum distribution, making the transformation of the electron energy spectrum from the laboratory frame to the

\begin{document}$ \Lambda_c^+ $\end{document}

rest-frame non-trivial. To address this, we develop a novel Bayesian inference method to reconstruct the electron energy moments in the

\begin{document}$ \Lambda_c^+ $\end{document}

rest-frame. By performing a global fit of theoretical predictions in the 1S mass scheme to these extracted moments, we determine the HQET parameters

\begin{document}$ \mu_\pi^2(\Lambda_c^+) $\end{document}

and

\begin{document}$ \rho_D^3(\Lambda_c^+) $\end{document}

for the first time using a purely data-driven approach.

Systematic study of microscopic nuclear level densities of Sn isotopes within a relativistic framework

Guanbin He, Nuocheng Tang, Yuan Tian, Ying Cui, Jian Li, Yi Xu, Ruirui Xu

Published: , doi: 10.1088/1674-1137/ae4329

Abstract:
Nuclear level density (NLD) plays a crucial role in describing the statistical properties of excited nuclei and is a key input for models of compound nuclear reactions, such as those used in nuclear astrophysics and reactor physics. In this work, we construct microscopic nuclear level densities for Sn isotopes by combining single-particle spectra, pairing correlations, and deformation parameters from relativistic Hartree–Bogoliubov (RHB) calculations with the combinatorial method. We examine the energy dependence and isotopic systematics of the calculated level densities. In particular, we analyze their variation with excitation energy and neutron number, and compare them to available experimental data, including cumulative low-lying levels and s-wave neutron resonance spacings (

\begin{document}$ D_0 $\end{document}

). The resulting level densities are further employed as input to Hauser–Feshbach calculations of radiative neutron capture

\begin{document}$ (n,\gamma) $\end{document}

cross sections [55]. Our results demonstrate that RHB-based nuclear level densities provide a reliable microscopic framework for describing Sn isotopic level densities and accurately predicting

\begin{document}$ (n,\gamma) $\end{document}

cross sections.

The perturbation solutions to the Blandford-Znajek mechanism in the Kerr-Sen black hole

Haiyuan Feng, Ziqiang Cai, Rong-Jia Yang, Jinjun Zhang

Published:

Abstract:
We investigate the steady, axisymmetric, force-free magnetosphere of Kerr–Sen black hole (BH) within the framework of the Einstein–Maxwell–dilaton–axion (EMDA) theory. By perturbatively solving the nonlinear Grad–Shafranov (GS) equation, we determine the magnetic field configuration and quantify the influence of the dilaton parameter r₂ on the energy extraction rate and radiative efficiency. Our results show that both the energy extraction power and the radiative efficiency increase with r₂, exceeding those of the standard Kerr BH, whereas the extraction efficiency remain consistent with the Kerr case. In addition, we perform χ² statistical analysis using observational data from six binary BH systems, which indicates that the Kerr BH currently provides a better fit for bulk Lorentz factors Γ = 2 and 5.

Minimal lepton models with non-holomorphic modular A₄ symmetry

Xiang-Yan Gao, Cai-Chang Li

Published:

Abstract:
We present a comprehensive bottom-up analysis of lepton mass and mixing based on the non-holomorphic

\begin{document}$A_{4}$\end{document}

modular symmetry. Neutrinos are assumed to be Majorana particles and the light neutrino masses are generated through the Weinberg operator. In this framework, we construct all phenomenologically viable models with minimal number of free parameters, where the Yukawa couplings are expressed in terms of polyharmonic Maa? forms of weights

\begin{document}$\pm4$\end{document}

,

\begin{document}$\pm2$\end{document}

and 0 at level

\begin{document}$N=3$\end{document}

. Without imposing generalized CP (gCP) symmetry, we identify 147 (6) viable models with eight real free parameters that successfully reproduce the current experimental data of lepton sector for the normal (inverted) mass ordering. When gCP symmetry consistent with

\begin{document}$A_{4}$\end{document}

modular symmetry is included, the number of free parameters is reduced by one, yielding 47 (5) phenomenologically viable models in the normal (inverted) mass ordering. Finally, we present detailed numerical analyses of a representative model for both mass orderings to illustrate these results.

Bridging doubly heavy tetraquark mass spectrum with heavy baryons utilizing heavy antiquark-diquark symmetry

Liu-Yu Zhang, Tian-Wei Wu, Yong-Liang Ma

Published:

Abstract:
Motivated by the observation of the doubly charmed tetraquark

\begin{document}$ T_{cc}(3875)^+ $\end{document}

, we present a systematic study of doubly heavy tetraquarks (

\begin{document}$ T_{QQ'\bar{q}\bar{q}'} $\end{document}

) using heavy antiquark-diquark symmetry (HADS) within a constituent quark model. By calibrating model parameters to known hadron spectra and incorporating the effective mass formula, we predict the masses for 38 ground-state tetraquarks with

\begin{document}$ cc $\end{document}

,

\begin{document}$ bb $\end{document}

, and

\begin{document}$ bc $\end{document}

heavy quark pairs, including the non-strange, single-strange, and double-strange configurations with quantum numbers

\begin{document}$ J^P = 0^+, 1^+ $\end{document}

and

\begin{document}$ 2^+ $\end{document}

. Notably, we identify several stable states below the relevant meson-meson thresholds, particularly in the

\begin{document}$ bb\bar{q}\bar{q}' $\end{document}

sector. The explicit connection between doubly heavy tetraquark and heavy baryon spectra through HADS reduces model dependence and reveals fundamental systematics in the heavy-quark hadron landscape.

The resonance effect for the CP asymmetry associated with the process ${\boldsymbol\omega{\bf\to}{\boldsymbol\pi}^+{\boldsymbol\pi}^-{\boldsymbol\pi}^{\bf 0} }$

Xi-Liang Yuan, Gang Lü, Na Wang, Chao Wang

Published: , doi: 10.1088/1674-1137/ad8ec2

Abstract:
The direct CP asymmetry in the weak decay process of hadrons is commonly attributed to the weak phase of the CKM matrix and the indeterminate strong phase. We propose a method to generate a significant phase difference through the interference between ρ and ω mesons, taking into account the G-parity allowed decay process of

\begin{document}$\omega \rightarrow \pi^{+}\pi^{-}\pi^{0}$\end{document}

and the G-parity-suppressed decay process of

\begin{document}$\rho^{0} \rightarrow \pi^{+}\pi^{-}\pi^{0}$\end{document}

in B meson decays. This interference can lead to notable changes in the CP asymmetry within the interference region. Additionally, we calculate the integral results for different phase space regions of the four-body decay process. We hope that our work provides valuable theoretical guidance for future experimental investigations on CP asymmetry in these decays.

Just Accepted