Long-range attractive interactions between dark matter particles can significantly enhance their annihilation, particularly at low velocities. This “Sommerfeld enhancement” is typically computed by evaluating the deformation of the two-particle wavefunction due to the long-range potential, while ignoring the physics associated with the annihilation, and then scaling the appropriate annihilation matrix elements by factors that depend on the wavefunction in the limit where the particles approach zero relative separation. It has long been recognized that this approach is a valid approximation only in the limit where the annihilation rate is small, and breaks down in the regime where the enhanced annihilation rate approaches the unitarity bound, in which case ignoring the impact of the annihilation physics on the two-particle wavefunction cannot be justified and leads to apparent violations of unitarity. In the case where the physics relevant to annihilation occurs at a parametrically shorter distance scale (higher energy scale) compared with the long-range potential, we provide a simple prescription for correcting the Sommerfeld enhancement for the effects of the short-range physics, valid for all partial waves and for systems where multiple states are coupled by the long-range potential.

United States

Aditya Parikh

Japan

Ryosuke Sato

Tracy Slatyer

Regulating Sommerfeld resonances for multi-state systems and higher partial waves

We quantize D0-brane, the simplest representative of the family of supersymmetric Dirichlet $\textit{p}$-branes, in its spinor moving frame formulation and analyze its quantum state spectrum. Besides being a preparatory stage for quantization of the complete supersymmetric multiple D0-brane (mD0) model, which is presently known only in the frame of spinor moving frame formalism, this is interesting as its own: despite the covariant quantization of D = 10 D0-brane was discussed before, its quantum state spectrum was not analyzed and its field theory, describing that, was not studied.

Spain

Igor Bandos

Unai Sarraga

Mirian Tsulaia

Quantum state spectrum and field theory of D0-brane

We study the electromagnetic form factors of electrically neutral dark-sector particles in this paper. Concretely speaking, we focus on the operators that can lead to interactions of fermionic dark states with the Standard-Model (SM) photon, including both dimension-5 (the magnetic and electric dipole moments) and dimension-6 (the anapole moment and charge radius) operators. Correspondingly, instead of the SM-photon form factors, we employ hypercharge gauge-field form factors that can induce additional couplings to the SM $\textit{Z}$-boson. Utilizing the mono-photon production channel at future linear electron-positron colliders, the International Linear Collider (ILC) and the Compact Linear Collider (CLIC), we demonstrate that tuning beam polarization allows for simultaneous enhancement of signal-event rates and suppression of dominant SM background events, i.e. neutrino-induced processes, and hence improvement of sensitivity reach. Our analysis reveals that ILC and CLIC can probe electromagnetic form factors of dark-sector particles up to about two orders of magnitude beyond existing experimental limits. We also estimate, at the order-of-magnitude level, the validity range of the effective-field-theory (EFT) approach we adopt, finding that for the dimension-5 operators the EFT remains valid in most of the parameter regions to which the ILC and CLIC can be sensitive, while it breaks down in the entire sensitivity region for the dimension-6 operators.

China

Zhong Zhang

Yu Zhang

Zeren Wang

Yunlan Ji

Probing dark-state electromagnetic form factors at future linear electron-positron colliders with polarized beams

High-precision regression of physical parameters from black hole images generated by General Relativistic Ray Tracing (GRRT) is essential for investigating spacetime curvature and advancing black hole astrophysics. However, owing to limitations in observational resolution, high observational costs, and imbalanced distributions of positive and negative samples, black hole images often suffer from data scarcity, sparse parameter spaces, and complex structural characteristics. These factors pose significant challenges to conventional regression methods based on simplified physical models. To overcome these challenges, this study introduces the Multiscale Adaptive Network (MANet), a novel regression framework grounded in deep learning. MANet integrates an Adaptive Channel Attention (ACA) module to selectively enhance features in physically informative regions. Meanwhile, a Multiscale Enhancement Feature Pyramid (MEFP) is employed to capture fine-grained spatial structures, such as photon rings and accretion disks, while alleviating information loss due to downsampling. Experimental evaluations on GRRT-simulated datasets demonstrate that MANet substantially improves parameter estimation accuracy and generalization capability in high-dimensional parameter spaces, outperforming existing baseline approaches. This framework presents a promising avenue for high-precision parameter regression in Event Horizon Telescope (EHT) data analysis and broader astrophysical imaging applications characterized by sparse and noisy data.

Jialei Wei

Ao Liu

Dejiang Li

Cuihong Wen

Physical parameter regression from black hole images using a multiscale adaptive neural network * Supported by the Natural Science Foundation of Hunan Province under grant No. 2023JJ30384; the National Natural Science Foundation of China under Grants No. 12374408; the University Students' Innovation and Entrepreneurship Training Program Project

The study of extra charged gauge bosons beyond the Standard Model has always been of great interest. Future muon colliders will have a significant advantage in discovering exotic particles. In this paper, by studying the $ \mu^+ \mu^- \to W^{\prime +} W^{\prime -} \to e^+ e^- n_e \bar{n}_e $ process, we explore the properties of $ W^\prime $ in the alternative left-right model. The cross section and angular distribution of the final electron are investigated in a scenario of different $ W^\prime $ masses and right-handed coupling constants. The forward-backward asymmetry is also an important observable to reflect the properties of $ W^\prime $ . We provide a method to effectively suppress the background processes by imposing constraints on the transverse momentum $ P_T $ and azimuthal angle of the final-state electrons $\textit{α}$. With cuts of $ 600 \lt P_T \lt 3500 $ GeV and $ 0.5 \lt \alpha \lt 3 $ , the significance exceeds 5$\textit{σ}$ for 4.8 TeV $ W^\prime $ at a collision energy of 10 TeV.

Liuxin Zhao

Honglei Li

Zhi-Long Han

Fei Huang

Xinyi Yan

Extra charged gauge boson $\textit{W}$′ in Alternative Left-Right Model at future muon collider * This work is supported by the Natural Science Foundation of Shandong Province (ZR2022MA065, ZR2024QA138), and University of Jinan Disciplinary Cross-Convergence Construction Project 2024 (XKJC-202404)

By capturing the characteristics of the Bethe-Salpeter amplitude for the pion excitation state, we construct an algebraic model to provide the overall features of the pion’s first excitation state parton distribution amplitude and distribution function. We find that, at the hadronic scale, the distribution amplitude of the excited state exhibits nodes, while the distribution function is unimodal, with a peak at $x=1/2 $ and distinct concave and convex fluctuations in the valence region. These findings provide new insights into the partonic structure of excited mesons and contribute significantly to our understanding of hadronic excitations.

Xiaobin Wang

Lei Chang

Unveiling the inner structure of the Pion’s first excited state * This work is financially supported by the National Natural Science Foundation of China (12135007)

The LHCb Collaboration has observed two types of hidden-charm pentaquark states $$ {P}_{\psi}^N $$ and $$ {P}_{\psi s}^{\Lambda} $$ since 2015. In this work, we predict two other types of hidden-charm pentaquark states $$ {P}_{\psi s}^{\Sigma} $$ (4367) and $$ {P}_{\psi ss}^N $$ (4379) within the framework of heavy pentaquark chiral perturbation theory. We suggest the LHCb Collaboration to observe $$ {P}_{\psi ss}^N $$ (4379) and $$ {P}_{\psi ss}^N $$ (4379) with $\textit{J}$ = $$ {\frac{1}{2}}^{-} $$ in the $\textit{J}$/$\textit{ψ}$Ξ spectrum through amplitude analyses of $$ {\Omega}_b^{-} $$ → $\textit{J}$/$\textit{ψ}$Ξ $\textit{K}$ decays and $$ {B}^{-}\to J/\psi {\Xi}^{-}\overline{\Lambda} $$ decays.

Hao-Song Li

Tao Li

Where is the next pentaquark state?

<p>The recently observed <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>K</mi><mo stretchy="false">(</mo><mn>1690</mn><mo stretchy="false">)</mo></math> has been identified as a supernumerary pseudoscalar resonance signal in the strange-meson spectrum predicted by quark model calculations. It is the best candidate of a strange cryptoexotic state. In this work, we systematically study the hadron masses of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>u</mi><mi>d</mi><mover accent="true"><mi>d</mi><mo stretchy="false">¯</mo></mover><mover accent="true"><mi>s</mi><mo stretchy="false">¯</mo></mover></math> tetraquark states with <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>J</mi><mi>P</mi></msup><mo>=</mo><msup><mn>0</mn><mo>−</mo></msup></math> in the method of QCD sum rules. For ten interpolating currents, we calculate the correlation functions up to dimension-8 nonperturbative condensates. To calculate the trigluon condensate, we comprehensively consider the contributions from different operators with and without covariant derivatives. The infrared safety can be guaranteed for the completely calculated trigluon condensate by properly addressing the IR divergences in Feynman diagrams. It is demonstrated that the trigluon condensate provides significant contributions to the sum-rule analyses in these light tetraquark systems. Our results support the interpretation of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>K</mi><mo stretchy="false">(</mo><mn>1690</mn><mo stretchy="false">)</mo></math> resonance to be a pseudoscalar <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>u</mi><mi>d</mi><mover accent="true"><mi>d</mi><mo stretchy="false">¯</mo></mover><mover accent="true"><mi>s</mi><mo stretchy="false">¯</mo></mover></math> tetraquark state.</p>

Jin-Peng Zhang

Xu-Liang Chen

Zi-Xi Ou-Yang

Xiang Yu

Wei Chen

Jia-Jun Wu

Unraveling <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>K</mi><mo stretchy="false">(</mo><mn>1690</mn><mo stretchy="false">)</mo></math> as a pseudoscalar <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>u</mi><mi>d</mi><mover accent="true"><mi>d</mi><mo stretchy="false">¯</mo></mover><mover accent="true"><mi>s</mi><mo stretchy="false">¯</mo></mover></math> tetraquark state

The recent report by the CMS Collaboration on the excess of top and anti-top pair production is examined with regard to the improvement of vacuum stability under two simple scenarios: one with the existence of toponium ( <italic>&#951;<inf>t</inf></italic>), and the other with an additional elementary field (&#936;). In both cases, the values of each coupling constant are restricted by the Multicritical Point Principle (MPP).

Yoshiki Matsuoka

On the Effects of Elementary and Bound State Fields on Vacuum Stability in <math altimg='si8.svg'><mrow><mi>t</mi><mover accent='true'><mi>t</mi><mo>&#175;</mo></mover></mrow></math> Production at the LHC

We investigate the no-boundary proposal for closed universes with an observer. We argue that the observer’s no-boundary state is the identity operator on the physical Hilbert space, i.e., the maximum entropy state and show this explicitly in Jackiw-Teitelboim gravity. Geometrically, the no-boundary state is a bra-ket wormhole. Expectation values in the no-boundary state provide a trace for the observer’s algebra, which allows one to define von Neumann entropy for observers in different universes as the relative entropy with respect to the no-boundary state. This result is consistent with all previously discussed cases of traces for invariantly defined regions.

Andreas Blommaert

Jonah Kudler-Flam

Erez Urbach

Absolute entropy and the observer’s no-boundary state