In this study, 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.

China

Bo-Xuan Shi

Hui-Xin Yu

Xue-Chen Zhao

Next-to-leading-order QCD predictions for the Σ Dirac form factors * This research is supported by the National Natural Science Foundation of China (12475097, 12535006) and the Natural Science Foundation of Tianjin (25JCZDJC01190). Xue-Chen Zhao is supported by the Postdoctoral Fellowship Program of CPSF (GZB20250794)

We present a comprehensive bottom-up analysis of lepton mass and mixing based on the non-holomorphic $A_{4}$ 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, with the Yukawa couplings expressed in terms of polyharmonic Maaß forms of weights $\pm4$ , $\pm2$ , and 0 at level $N=3$ . Without imposing generalized CP (gCP) symmetry, we identify 147 (six) viable models with eight real free parameters that successfully reproduce the current experimental data of the lepton sector for the normal (inverted) mass ordering. When gCP symmetry consistent with $A_{4}$ modular symmetry is included, the number of free parameters is reduced by one, yielding 47 (five) 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.

Xiang-Yan Gao

Cai-Chang Li

Minimal lepton models with non-holomorphic modular $\textit{A}$ $_{4}$ symmetry * Supported by Natural Science Basic Research Program of Shaanxi (2024JC-YBQN-0004) and the National Natural Science Foundation of China (12547106, 12247103)

The quark-mass dependence of the $ N^*(920) $ pole is analyzed using the $\textit{K}$-matrix method, with the $ \pi N $ scattering amplitude calculated up to the $ O(p^3) $ order in the chiral perturbation theory. As the quark mass increases, the $ N^*(920) $ pole gradually approaches the real axis in the complex $\textit{w}$-plane (where $ w=\sqrt{s} $ ). Eventually, in the $ O(p^2) $ case, it crosses the $\textit{u}$-cut on the real axis and enters the adjacent Riemann sheet when the pion mass reaches $ 526\; {\rm{MeV}} $ . At order $ O(p^3) $ , the rate at which it approaches the real axis decreases; however, it remains uncertain whether it will ultimately cross the $\textit{u}$-cut and enter the adjacent Riemann sheet. In addition, the trajectory of the $N^*(920)$ pole is in qualitative agreement with the results from the linear $\textit{σ}$ model calculation.

Xu Wang

Kai-Ge Kang

Qu-Zhi Li

Zhiguang Xiao

Han-Qing Zheng

Studies on quark-mass dependence of the $\textit{N}$ $^{*}$(920) pole from unitarized $\textit{πN}$ $\textit{χ}$PT amplitudes * Supported by China National Natural Science Foundation (12335002, 12375078) and the Fundamental Research Funds for the Central Universities

The interference between amplitudes corresponding to different intermediate resonances plays an important role in generating large CP asymmetries in the phase space in multi-body decays of bottom and charmed mesons. In this study, we examine the CP violation in the decay channel $ {\overline{B}}^{0}\rightarrow K^{-}\pi^{+}\pi^{0} $ in the phase-space region where the intermediate resonances $ \overline{K}^{*}(892)^{0} $ and $ {\overline{K}^{*}_{0}(700)} $ dominate. In particular, the forward-backward asymmetry (FBA) and the CP asymmetry induced by FBA (FB-CPA), which are closely related to the interference effects between the two aforementioned resonances, are investigated. The nontrivial correlation between FBA and FB-CPA is analyzed. The analysis indicates that FB-CPAs around the resonance $ \overline{K}^{*}(892)^{0} $ can be as large as approximately 35%, which can be potentially accessible by Belle and Belle-II collaborations in the near future.

Jian-Yu Yang

Yu-Jie Zhao

Jing-Juan Qi

Zhen-Hua Zhang

The forward-backward asymmetry induced CP asymmetry in ${{\overline{B}}^{0}\rightarrow K^{-}\pi^{+}\pi^{0}}$ in phase space around the resonances ${{\overline{K}}^{*}(892)^{0}}$ and ${{\overline{K}}^{*}_{0}(700)}$ * Supported by National Natural Science Foundation of China (12475096, 12405115, 12192261) and Scientific Research Fund of Hunan Provincial Education Department (22A0319)

The Schwinger effect, a non-perturbative mechanism for particle production in strong fields, plays a crucial role in understanding quantum vacuum decay and high-energy phenomena, including heavy-ion collisions (HIC). Although holographic quantum chromodynamics (QCD) models have been widely used to study this effect, most treatments assume isotropy or consider only a single type of anisotropy, neglecting the interplay between spatial and magnetic anisotropies that arise in realistic HIC scenarios. A unified framework accounting for both anisotropies is needed to accurately model particle production. We investigate the Schwinger effect in a twice anisotropic holographic QCD model incorporating both spatial and magnetic anisotropies. Using the anti-de Sitter/conformal field theory correspondence, we compute the total potential of a particle-antiparticle pair to quantify how these anisotropies influence pair production. Our results show that the magnetic field (parameterized by $c_B$ and $q_3$ ) enhances the Schwinger effect by lowering and narrowing the potential barrier, while increasing spatial anisotropy (controlled by $\nu$ ) suppresses the process by raising and widening the barrier. These findings demonstrate that magnetic and spatial anisotropies exert competing effects on particle production, emphasizing the necessity of treating both concurrently in holographic models. This work advances the theoretical description of the Schwinger effect in anisotropic environments, with implications for understanding non-equilibrium dynamics in HIC and other strongly coupled systems.

Wen-Bin Chang

Defu Hou

Schwinger effect in a twice anisotropic holographic model * Defu Hou's research is supported in part by the National Key Research and Development Program of China (2022YFA1604900). Additionally, Defu Hou receives partial support from the National Natural Science Foundation of China (NSFC) (12435009, 12275104). Wen-Bin Chang is supported by the Ph.D. Research Startup Project at Hubei Minzu University (RZ2500000857)

The photon sphere, a hypersurface of null circular geodesics, plays a fundamental role in characterizing black hole spacetimes, influencing phenomena such as black hole shadows, gravitational lensing, and quasinormal modes. In this work, we derive both upper and lower bounds on the photon sphere radius for static, spherically symmetric, asymptotically flat black holes within $\textit{n}$-dimensional Einstein gravity $$(n\ge 4)$$ , assuming an anisotropic matter field satisfying the weak energy condition and a non-positive trace of the energy–momentum tensor. For the upper bound, we obtain $$r_\gamma \le [(n-1)M]^{\frac{1}{n-3}},$$ where $\textit{M}$ is the ADM mass. In the four-dimensional case $$(n=4)$$ , this reduces to $$r_\gamma \le 3M,$$ in agreement with previous results. For the lower bound, under the additional assumption that $$|r^{n-1}p_r(r)|$$ is monotonically decreasing, we prove $$r_\gamma \ge (\frac{n-1}{2})^{1/(n-3)}r_H,$$ where $$r_H$$ is the radius of the outer event horizon; for $$n=4$$ this gives $$r_\gamma \ge \frac{3}{2}r_H,$$ also consistent with previous four-dimensional result. These results provide dimension-dependent geometric constraints that generalize well-known four-dimensional bounds to a specific class of higher-dimensional black holes (described by a Tangherlini-type metric) and deepen our understanding of spacetime structure in higher-dimensional gravitational theories.

Yong Song

Jiaqi Fu

Yiting Cen

Bounds on the photon sphere radius for spherically symmetric black holes in $${\varvec{n}}$$ -dimensional Einstein gravity

We present a new M package that provides a platform to perform multi-loop computations. A integrates several existing tools designed for higher-order computations. In particular, it uses QG to generate Feynman diagrams and relies on F to perform the Dirac and colour algebras. This makes it very efficient without compromising user-friendliness and flexibility. In addition, A is equipped with functionalities to manipulate the generated amplitudes and to extract scalar form factors. The resulting expressions can be mapped to integral families that can subsequently be reduced to master integrals via dedicated interfaces to codes for integration-by-parts reduction. Support for large classes of BSM models with the same gauge group as the SM is provided, and in particular A is optimised for computations in effective field theories. We review and introduce the main functionalities of A and illustrate its use for phenomenological applications.

Germany

Claude Duhr

Pooja Mukherjee

Andres Vasquez

ANATAR: AN Automated Tool for higher-order Amplitude geneRation

Monochromatic high-frequency gravitational waves (HFGWs) provide a distinctive probe of new physics scenarios, most notably axion clouds around rotating black holes formed via superradiance. We reanalyzed data from the CAPP-12T multicell axion haloscope experiment [Kim et al., <a href="http://dx.doi.org/10.1103/PhysRevLett.133.051802">Phys. Rev. Lett. 133, 051802 (2024)</a>]. The study covers a continuous 2 MHz frequency span centered at 5.311 GHz. No rescan candidates were found, and we set 90% confidence-level exclusion limits on the gravitational-wave strain, reaching <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>h</mi><mn>0</mn></msub><mo>≈</mo><mn>3.9</mn><mo>×</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>21</mn></mrow></msup></math> in the most sensitive regions of the sky. Interpreted in the context of black hole superradiance from axion clouds, the results exclude black holes with mass <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>M</mi><mi>BH</mi></msub><mo>≃</mo><mn>1.22</mn><mo>×</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>6</mn></mrow></msup><msub><mi>M</mi><mo stretchy="false">⊙</mo></msub></math> within distances of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi mathvariant="script">O</mi><mo stretchy="false">(</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>2</mn></mrow></msup><mo stretchy="false">)</mo></mrow></math> AU from Earth, under benchmark assumptions. This work demonstrates the potential of electromagnetic resonant cavities as novel detectors of monochromatic HFGWs and motivates future searches for both long-lived and transient signals.

Younggeun Kim

Jordan Gué

Changhao Xu

Diego Blas

Dmitry Budker

Sungjae Bae

Claudio Gatti

Junu Jeong

Jihn E. Kim

Kiwoong Lee

Arjan F. van Loo

Yasunobu Nakamura

Seonjeong Oh

Wolfram Ratzinger

Taehyeon Seong

Yannis K. Semertzidis

Kristof Schmieden

Mattias Schott

Sergey Uchaikin

SungWoo Youn

Search for high-frequency gravitational waves via reanalysis of cavity axion data

We construct dimer graphs for relativistic Toda chains associated with classical untwisted Lie algebras of A, B, C , C , D types and twisted A, D types. We show that the Seiberg-Witten curve of 5d $$ \mathcal{N} $$ = 1 pure supersymmetric gauge theory of gauge group $\textit{G}$ is a spectral curve of the relativistic Toda chain of the dual group $\textit{G}$ .

Kimyeong Lee

South Korea

Norton Lee

Dimers for relativistic Toda models with reflective boundaries

Experiments at the CERN Large Hadron Collider (LHC) have accumulated an unprecedented amount of data corresponding to a large variety of quantum states. Although searching for new particles beyond the Standard Model of particle physics remains a high priority for the LHC program, precision measurements of the physical processes predicted in the Standard Model continue to lead us to a deeper understanding of nature at high energies. We carry out detailed simulations for the process $\textit{pp}$ → $\textit{τ}$ $\textit{τ}$ $\textit{X}$ to perform quantum tomography and to measure the quantum entanglement and the Bell nonlocality of the $\textit{τ}$ $\textit{τ}$ two qubit state, including both statistical and systematic uncertainties. By using advanced machine learning techniques for neutrino momentum reconstruction, we achieve precise measurements of the full spin density matrix, a critical advantage over previous studies limited by reconstruction challenges for missing momenta. Our analysis reveals a clear observation of Bell nonlocality with high statistical significance, surpassing 5$\textit{σ}$, establishing $\textit{τ}$ $\textit{τ}$ as an ideal system for quantum information studies in high-energy collisions. Given its experimental feasibility and the high expected sensitivity for Bell nonlocality, we propose that $\textit{τ}$ $\textit{τ}$ should be regarded as the new benchmark system for quantum information studies at the LHC, complementing and extending the insights gained from the $$ t\overline{t} $$ system.

United States

Yulei Zhang

Bai-Hong Zhou

Qi-Bin Liu

Tong Wu

Shu Li

Tao Han

Shih-Chieh Hsu

Matthew Low

Entanglement and Bell nonlocality in $\textit{τ}$ + $\textit{τ}$ $\textit{−}$ at the LHC using machine learning for neutrino reconstruction