A new measurement of the $^{65}$Cu($\textit{γ}$, $\textit{n}$)$^{64}$Cu photoneutron cross section is performed using quasi-monoenergetic, tunable $\textit{γ}$-ray beams produced at the Shanghai Laser Electron Gamma Source (SLEGS). The energy spectrum of the SLEGS $\textit{γ}$-ray beams incident on the isotopically enriched $^{65}$Cu target is monitored using a BGO detector, while the photoneutron yields are determined with a moderated $^{3}$He detection array with high and flat efficiency. Within the energy range of $10.1 \le E_\gamma \le 17.6$ MeV, the measured $\sigma(E_\gamma)$ data have an uncertainty of $\lesssim 4$ %, and a pronounced giant-dipole peak is observed at $E_\gamma \simeq 16.65$ MeV with a maximal cross section of $\sigma_{\text{max}} \simeq 137$ mb. These photoneutron data are compared with previous experimental results and are employed to extract the $\textit{γ}$-ray strength function of $^{65}$Cu above the neutron threshold. Furthermore, we calculate the radiative neutron capture cross sections and astrophysical reaction rates for $^{64}$Cu, which is a short-lived intermediate nucleus whose reaction rate controls the local abundance distribution in the weak $\textit{s}$-process. It is found that the calculated $^{64}$Cu($\textit{n,}$ $\textit{γ}$)$^{65}$Cu data have an overall agreement with ENDF/B-VIII.0, JEFF-3.3, and TENDL-2023 evaluations, and the corresponding astrophysical reaction rates are consistent with those reported in the JINA REACLIB database.

China

Yu-Long Shen

Zi-Rui Hao

Qian-kun Sun

Hong-Wei Wang

Long-Xiang Liu

Hang-Hua Xu

Yue Zhang

Sheng Jin

Kai-Jie Chen

Meng-Die Zhou

Zhen-Wei Wang

Meng-Ke Xu

Xiang-Fei Wang

Chang Yang

Pu Jiao

Chun-Wang Ma

Gong-Tao Fan

Zhi-Cai Li

Wen Luo

Photoneutron cross section measurements on $^{65}$Cu: toward understanding ($\textit{n,}$ $\textit{γ}$) cross sections relevant to weak $\textit{s}$-process nucleosynthesis * This work was supported by the National Key Research and Development Program (2023YFA1606901), and the National Natural Science Foundation of China (12575133, 12505144)

Using the pinch technique, we determine the one-loop vertices of weak interactions in the B-LSSM and incorporate their pinch contributions into the gauge boson self-energies. Compared to the definitions of the $\textit{S}$, $\textit{T}$, and $\textit{U}$ parameters in the Standard Model based on the $S U(2)_L \otimes U(1)_Y$ group, the corresponding parameters in the local B-L gauge symmetry (B-LSSM) are modified. We present these redefined $\textit{S}$, $\textit{T}$, and $\textit{U}$ parameters and demonstrate the convergence of the results. In the framework of the low-energy effective Lagrangian for weak interactions, the $\textit{S}$, $\textit{T}$, and $\textit{U}$ parameters can be expressed as functions of specific parameters in the B-LSSM. The updated experimental and fitting results strongly constrain the parameter space of the B-LSSM.

Sheng-Kai Cui

Ke-Sheng Sun

Yu-Li Yan

Jin-Lei Yang

Tai-Fu Feng

$\textit{S}$, $\textit{T}$, $\textit{U}$ parameters in the B-LSSM * Supported by the Natural Science Foundation of Guangxi Autonomous Region (2022GXNSFDA035068), the Natural Science Foundation of Hebei Province (A2022104001), and the Foundation of Baoding University (2023Z01)

The Galactic Center GeV Excess (GCE) remains a compelling but enigmatic signal from the inner regions 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 multimessenger observations. Based on the viable nonresonant parameter space identified in previous global fits, we perform a comprehensive study on the prospects for discovering such muonphilic DM in the context of a future 3 TeV muon collider, focusing on simplified models with a $Z_2$ -even mediator. Four distinct search strategies are investigated: visible on-shell mediator decays ( $\mu^{+}\mu^{-}\gamma$ 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 $ 95 $ % 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 viable parameter space that explains the GCE, establishing a muon collider as a decisive machine for testing the muonphilic DM hypothesis.

Wanyun Chen

Haoqi Li

Chih-Ting Lu

Qiulei Wang

Exploring muonphilic dark matter with the $\textit{Z}$ $_{2}$-even mediator at muon colliders * Chih-Ting Lu, Wanyun Chen and Haoqi Li are supported by the National Natural Science Foundation of China (NNSFC) (12335005, 12575118) and the Special funds for postdoctoral overseas recruitment, Ministry of Education of China

The processes of $ K^-p \to \pi^0 \pi^0 \Sigma^0 $ and $ K^- p \to \pi^0 \Lambda(1405) $ are studied within the effective Lagrangian approach. In addition to the “background” contribution from the $\textit{u}$-channel nucleon pole term, the contribution from the $ \Sigma(1660) $ resonance with spin-parity $ J^P=1/2^+ $ is also considered. For the $ K^-p \to \pi^0 \pi^0 \Sigma^0 $ reaction, we perform a calculation for the total and differential cross sections by considering the contribution from the $ \Sigma(1660) $ intermediate resonance decaying into $ \pi^0 \Lambda(1405) $ with $ \Lambda(1405) $ decaying into $ \pi^0 \Sigma^0 $ . With our model parameters, the available experimental data on both the $ K^-p \to \pi^0 \pi^0 \Sigma^0 $ and $ K^- p \to \pi^0 \Lambda(1405) $ reactions can be fairly well reproduced. It is shown that the contribution from the $ \Sigma(1660) $ resonance is necessary, and that these experimental measurements could be used to determine some properties of the $ \Sigma(1660) $ resonance.

Xing-Yi Ji

Si-Wei Liu

Wen-Tao Lyu

De-Min Li

En Wang

Ju-Jun Xie

Role of Σ(1660) in the $\textit{K}$ $^{−}$ $\textit{p}$ → $\textit{π}$ $^{0}$ $\textit{π}$ $^{0}$Σ$^{0}$ reaction * Supported by the National Key R&D Program of China (2023YFA1606703, 2024YFE0105200), the National Natural Science Foundation of China (12435007, 12475086, 12192263, 12361141819, 1252200936), the Natural Science Foundation of Henan (232300421140, 252300423951) and the Zhengzhou University Young Student Basic Research Projects (PhD students) (ZDBJ202522)

We have performed an updated analysis of the angular distribution of the $ \psi(3686) \to p\bar{p} $ decay by considering transverse beam polarization to investigate potential sources of forward-backward asymmetry and azimuthal modulation beyond the simple $ 1+\alpha\cos^2\theta $ form. We focus on the interference between the $ \psi(3686) $ resonance and two-photon exchange continuum process, as well as on the background from initial-state–final-state radiation (ISR–FSR) interference. A maximum-likelihood fit to the $ \cos\theta $ distribution of $ \psi(3686)\to p\bar{p} $ yields $ \alpha = 1.00 \pm 0.03 $ , which is consistent with previous results. Our model predicts a significant $ \sin(2\phi) $ modulation in the azimuthal angle, indicating the influence of transverse beam polarization. Based on these findings, two-dimensional angular analyses can be conducted in the future to fully disentangle the polarization and interference dynamics in charmonium decays to baryon pairs.

Zhi Gao

Rong-Gang Ping

Minggang Zhao

Update analysis of $ {\psi(3686)\to p\bar{p}}$ * The work is partly supported by the National Natural Science Foundation of China(NSFC) (12575112)

This study investigates the ultraviolet realization of semileptonic four-fermion operator $ O_{ledq}^{\alpha \beta 11} $ 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, thereby effectively alleviating the lower bounds on the new physics scale. In addition, we investigate the interplay between 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. We found that both the projected future constraint on the LFC Wilson coefficient $ C_{ledq}^{2211}/\Lambda^2 \lt $ $ (12.3\; \text{TeV})^{-2} $ from the measurements of neutrino non-standard interaction in the next-generation neutrino oscillation experiments, and the LFV constraint $ C_{ledq}^{1211}/\Lambda^2 \lt \left(2.2\times 10^3\; \text{TeV} \right)^{-2} $ from ongoing charged-lepton-flavor-violation searches, provide a complementary exploration of the parameter space encompassing the DM and scalar masses. With a colored mediator mass of approximately $ 2\; \text{TeV} $ , the sensitivity of the indirect constraints on the four-fermion operator can 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 find that the collider searches and DM direct detection are more sensitive to the electroweak-scale DM and scalar than indirect constraints.

Yuxuan He

Gang Li

Jia Liu

Xiao-Ping Wang

Xiang Zhao

Lepton flavor of four-fermion operator and fermion portal dark matter * Gang Li and Xiang Zhao are supported by the National Natural Science Foundation of China (12347105, 12505127), the Guangdong Basic and Applied Basic Research Foundation (2024A1515012668). The work of Jia Liu is supported by the National Science Foundation of China (12235001, 12475103) and State Key Laboratory of Nuclear Physics and Technology (NPT2025ZX11). The work of Xiao-Ping Wang is supported by National Science Foundation of China (12375095) and the Fundamental Research Funds for the Central Universities

We have performed a next-to-leading-order (NLO) QCD sum rules analysis of the $1^{-+}$ 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 $1.7\,\text{GeV}$ . We have identified multiple $1^{-+}$ states around $2.0\,\text{GeV}$ matching well with $\pi_{1}(2015)$ , confirming that $\pi_{1}(2015)$ is an excellent tetraquark candidate. By contrast, our calculations exclude the possibility that the $\pi_{1}(1400)$ is a tetraquark or hybrid–tetraquark mixture. This result suggests that it may not exist, which is consistent with recent experimental results.

Wei-Yang Lai

Hong-Ying Jin

NLO QCD sum rules analysis of 1$^{− +}$ tetraquark states

A number of recent papers have claimed to construct solutions of Einstein’s equations describing black holes surrounded by dark-matter halos with empirically motivated density profiles such as the Navarro–Frenk–White, Burkert, Einasto, pseudo-isothermal, and solitonic distributions. We show that the approach used to obtain many of these metrics generically does not lead to the correct solutions to the Einstein equations for the matter sources they purport to represent. This issue originates from applying the Newtonian relation between the tangential velocity and the enclosed mass directly within a relativistic framework, followed by the ad hoc assumption $$g(r)=f(r)$$ for the metric functions. This procedure leads to an anisotropic fluid with $$P_r=-\rho $$ and $$P_t=-r\rho '/2-\rho $$ , whose density differs from the claimed halo profile and often becomes non-physical near the horizon, violating the weak energy condition. As a result, the obtained spacetimes do not describe black holes embedded in known galactic halos but rather distinct anisotropic configurations unrelated to the intended matter distribution. We demonstrate this problem on several representative examples from the literature, including metrics based on the NFW, Burkert, Einasto, solitonic, pseudo-isothermal, and Dehnen-(1,4,5/2) profiles, as well as the case of the NGC 4649 halo. For each case, the correct Einstein-consistent form of the metric and the associated physical interpretation are provided. Our analysis clarifies the limits of validity of the Newtonian approximation near compact objects and establishes a consistent framework for constructing dark-matter–inspired black-hole geometries within General Relativity.

Russia

S. Bolokhov

Revisiting black holes in dark-matter halos: on consistent solutions to the Einstein equations

In this work we study a scale invariant gravity theory containing two scalar fields, dust particles and a measure defined from degrees of freedom independent of the metric. The integration of the degrees of freedom that define the measure spontaneously break the scale symmetry, leaving us in the Einstein frame with an effective potential that is dependent on the density of the particles. The potential contains three flat regions, one for inflation, another for early dark energy and the third for late dark energy. At a certain point, as the matter dilutes, tunneling from the early dark energy to the late dark energy can start efficiently. This mechanism naturally alleviated the observed Hubble tension by modifying the sound horizon prior to recombination while preserving late-time cosmology. Moreover, the model predictions are consistent with observations from the reduced CMB, BAO, and local measurement of $$H_0$$ , providing a coherent and unified description of the universe. In this context, the Bayesian analysis of these datasets confirms the viability of our scenario, with the best-fit parameters indicating an early dark energy fraction of $$f_\textrm{NEDE}\approx 0.3$$ at a redshift of $$z^{\prime }=5000$$ . This preliminary estimate, obtained using the reduced CMB dataset, is expected to be tightened once the full CMB likelihood is considered.

Germany

Bahamas

Israel

Eduardo Guendelman

Chile

Ramón Herrera

Pedro Labraña

Connecting early dark energy to late dark energy by the diluting matter potential

Black holes in dense astrophysical environments, such as globular clusters or in the vicinity of other massive objects, may possess accelerations. Such acceleration would modulate the characteristics of the quasi-periodic oscillations (QPOs) observed in X-ray black hole binaries. In this paper, we explore the influence of spin-aligned acceleration of a black hole on QPOs observed in X-ray binaries. For this purpose, we compute the fundamental frequencies arising from the motion of test particles around an accelerating (spin-aligned) black hole and apply the relativistic precession, parametric resonance, and forced resonance models to establish their correspondence with several observed QPOs of X-ray binaries (GRO J1655-40, XTE J1550-564, XTE J1859+226, GRS 1915+105, H1743-322, M82 X-1, and Sgr A $$^{*}$$ ). We then employ the Bayesian Markov-Chain Monte Carlo method to constrain the black hole parameters. Our results show no evidence for spin-aligned acceleration in any of the analyzed sources, suggesting that most of these X-ray binaries reside in isolated environments and therefore experience only small perturbations to the background spacetime geometries.

Azerbaijan

Hamza Rehman

Saddam Hussain

Pakistan

G. Abbas

Tao Zhu

Exploring the accelerating black holes from the observations of quasi-periodic oscillations in X-ray binaries