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.

China

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)

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

Along the last 10 years, a general relativistic method has been developed to generate analytical expressions for the black hole (BH) parameters in terms of observables, namely the frequency shift of photons emitted by orbiting test particles and their positions on the sky. Applications of the method to astrophysical systems such as Active Galactic Nuclei (AGNs), in particular to megamaser systems orbiting the central BH on their flat accretion disks, showed a coupling behavior in the mass-to-distance ratio $\textit{M}$/$\textit{D}$. Estimates for the ratio $\textit{M}$/$\textit{D}$ of a sample of BHs hosted at the core of several AGNs have been performed in recent years with the help of this method. However, both analytical expressions and statistical estimations depend only on the $\textit{M}$/$\textit{D}$ ratio rather than on independent parameters. It is of current general interest to work with decoupled parameters in order to safeguard the intrinsic physical information encoded in each of them, given their high scientific relevance in understanding the structure of our Universe. The purpose of this work is to find analytical expressions for the mass and distance of a Schwarzschild BH in terms of astrophysical observables by introducing a slight warping in the accretion disk of the orbiting megamasers. As a result, independent analytical formulas for the mass and distance of AGN supermassive BHs are presented in terms of astrophysical observables: maser frequency shifts, disk parameters, and the galaxy’s peculiar redshift.

Mexico

A. González-Juárez

A. Herrera-Aguilar

Mass and distance of AGN black holes from warped accretion disks

We show that, in two-dimensional Euclidean quantum gravity without matter fields, the Schwinger-Dyson equations derived within the Hamiltonian framework of non-critical string field theory can be reformulated in terms of the Chekhov-Eynard-Orantin topological recursion, and we explicitly compute the associated low-order amplitudes. In particular, we establish this reformulation for two discrete models — the basic type and the strip type — as well as for the continuum limit of dynamical triangulations.

Japan

Hiroyuki Fuji

Masahide Manabe

Yoshiyuki Watabiki

Dynamical triangulations for 2D pure gravity and topological recursion

Light-cone distribution amplitudes (LCDAs) are essential to precision phenomenology in heavy baryon decays. In this work, we derive a factorization formula connecting the leading-twist QCD LCDA to the boosted HQET LCDA of the Λ baryon in the peak region. We demonstrate a significant simplification of the matching procedure by applying the method-of-regions to perturbative calculations. With this simplification, we calculate the required one-loop perturbative corrections to the QCD and boosted HQET LCDAs in the $$ \overline{\textrm{MS}} $$ scheme, and thereby obtain the one-loop jet function that serves as the matching kernel in the factorization formula. We have also performed the matching of the Λ decay constants in QCD and boosted HQET, leading to the final factorization formula connecting the LCDAs in these two theories. A detailed discussion of the Λ QCD LCDA in the tail region is provided. This work provides an essential step toward lattice QCD calculation of heavy baryon LCDAs in the future.

Yu-Ji Shi

Jun Zeng

Factorization formula connecting the Λ $\textit{b}$ LCDA in QCD and boosted HQET

We study a model in which a new interactions between the Standard Model (SM) photon and both the dark photon (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>γ</mi><mi>D</mi></msub></math>) and an axionlike particles (ALP or <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>a</mi></math>) are described by the dark axion portal operator. The implications of this dark axion portal scenario for electron fixed-target experiments are presented. In particular, we investigate the missing energy signatures associated with production of dark photons and their subsequent invisible decays into stable dark sector fermions, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>γ</mi><mi>D</mi></msub><mo stretchy="false">→</mo><mi>χ</mi><mover accent="true"><mi>χ</mi><mo stretchy="false">¯</mo></mover></math>. We discuss the discovery potential for such a scenario and derive projected sensitivity curves for the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>NA</mi><mrow><mn>64</mn><mi>e</mi></mrow></mrow></math> and LDMX experiments. Furthermore, novel constraints of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>NA</mi><mrow><mn>64</mn><mi>e</mi></mrow></mrow></math> for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>9.37</mn><mo>×</mo><msup><mn>10</mn><mn>11</mn></msup></math> electrons on target are derived by considering two production mechanisms for invisible states: (i) the bremsstrahlung-like emission of an <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>a</mi><msub><mi>γ</mi><mi>D</mi></msub></math> pair, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>e</mi><mi>N</mi><mo stretchy="false">→</mo><mi>e</mi><mi>N</mi><msup><mi>γ</mi><mo>*</mo></msup><mo stretchy="false">(</mo><mo stretchy="false">→</mo><mi>a</mi><msub><mi>γ</mi><mi>D</mi></msub><mo stretchy="false">)</mo></math>, and (ii) the exclusive vector meson photoproduction, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>γ</mi><mo>*</mo></msup><mi>N</mi><mo stretchy="false">→</mo><mi>N</mi><mi>V</mi></math>, followed by the invisible decays of vector mesons, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>V</mi><mo stretchy="false">→</mo><mi>a</mi><msub><mi>γ</mi><mi>D</mi></msub></math>. Additionally, the constraints on the parameter space of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><mi>P</mi></math>-violating, fermion-specific ALP and dark photon couplings are established. These constraints are derived from current experimental bounds on the electric dipole moments (EDMs) of SM fermions, incorporating loop-induced contributions to the EDMs of the electron, muon, and neutron.

Russia

Chile

JINR

Sergei N. Gninenko

N.V. Krasnikov

Germany

Valery E. Lyubovitskij

Sergey Kuleshov

Alexey S. Zhevlakov

I.V. Voronchikhin

D.V. Kirpichnikov

Constraints on dark axion portal: Missing energy and fermion EDMs

The thermodynamic geometry of the hadron resonance gas model with (without) excluded volume effects (EVE) of baryons is investigated. The case with imaginary <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>μ</mi></math>, where <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>μ</mi></math> is the baryon chemical potential, is investigated as well as the one with real <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>μ</mi></math>. We calculate the scalar curvature <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>R</mi></math> and use the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>R</mi><mo>=</mo><mn>0</mn></math> criterion to investigate the phase structure in the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>μ</mi><mn>2</mn></msup><mo>−</mo><mi>T</mi></math> plane where <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>T</mi></math> is the temperature. The curve on which <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>R</mi><mo>=</mo><mn>0</mn></math> continues analytically from the imaginary <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>μ</mi></math> region, where the lattice QCD is feasible, to the real <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>μ</mi></math> one. In the presence of EVE, there are rich phase structures in the large real <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>μ</mi></math> region as well as the Roberge-Weiss-like region where <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>μ</mi></math> is imaginary and a singularity appears, while there is no phase structure in the large real <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>μ</mi></math> region in the absence of EVE. The limiting temperature of the baryon gas is also obtained by using the baryon number fluctuation. The LQCD predicted critical point locates almost on the curve of the limiting temperature we determined. A simple empiric sufficient condition, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>n</mi><mi mathvariant="normal">B</mi></msub><mo>&gt;</mo><mn>1</mn><mo>/</mo><mo stretchy="false">(</mo><mn>2</mn><msub><mi>v</mi><mi mathvariant="normal">B</mi></msub><mo stretchy="false">)</mo></math>, is obtained for the quark deconfinement in the large real <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>μ</mi></math> region, where <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>n</mi><mi mathvariant="normal">B</mi></msub></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>v</mi><mi mathvariant="normal">B</mi></msub></math> are the net baryon number density and the volume of a baryon, respectively.

Riki Oshima

Hiroaki Kouno

Azerbaijan

Motoi Tachibana

Kouji Kashiwa

Thermodynamic geometry in the hadron resonance gas model at real and imaginary baryon chemical potential and a simple sufficient condition for quark deconfinement

Dark matter (DM) models with a conserved particle-antiparticle number, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>n</mi></mrow><mrow><mi>χ</mi></mrow></msub><mo>−</mo><msub><mrow><mi>n</mi></mrow><mrow><mover accent="true"><mrow><mi>χ</mi></mrow><mrow><mo stretchy="false">˜</mo></mrow></mover></mrow></msub></mrow></math>, and the asymmetry in the cosmological abundance <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>n</mi></mrow><mrow><mi>χ</mi></mrow></msub><mo>≠</mo><msub><mrow><mi>n</mi></mrow><mrow><mover accent="true"><mrow><mi>χ</mi></mrow><mrow><mo stretchy="false">˜</mo></mrow></mover></mrow></msub></mrow></math>, are known to be challenged by the existence of old neutron stars (NSs), as the sufficient accumulation of DM will lead to the collapse of NSs into black holes. We demonstrate that the applicability of these constraints is much wider and covers models with symmetric populations of DM, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>n</mi></mrow><mrow><mi>χ</mi></mrow></msub><mo>=</mo><msub><mrow><mi>n</mi></mrow><mrow><mover accent="true"><mrow><mi>χ</mi></mrow><mrow><mo stretchy="false">˜</mo></mrow></mover></mrow></msub></mrow></math>, as the process of DM capture regulated by a nucleon-DM scattering can be inherently asymmetric, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>σ</mi></mrow><mrow><mi>χ</mi><mi>n</mi></mrow></msub><mo>≠</mo><msub><mrow><mi>σ</mi></mrow><mrow><mover accent="true"><mrow><mi>χ</mi></mrow><mrow><mo stretchy="false">˜</mo></mrow></mover><mi>n</mi></mrow></msub></mrow></math>. The asymmetry is induced by the interference of different types of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>χ</mi><mtext>−</mtext><mi>n</mi></mrow></math> interactions, provided that their combination is odd under charge conjugation in the DM sector, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>C</mi><mi>χ</mi></msub></math>, and even under combined parity <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>P</mi></mrow><mrow><mi>χ</mi><mo>+</mo><mi>n</mi></mrow></msub></mrow></math>. We provide a complete analysis of DM-nucleon bilinear <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>χ</mi><mtext>−</mtext><mi>n</mi></mrow></math> interactions and find that this asymmetry is very generic. Using canonical NS parameters and local DM halo inputs, we exclude spin-averaged scattering cross sections down to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>σ</mi></mrow><mrow><mi>n</mi><mi>χ</mi></mrow></msub><mo>≳</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>46</mn></mrow></msup><mtext> </mtext><mtext> </mtext><msup><mrow><mi>cm</mi></mrow><mrow><mn>2</mn></mrow></msup></mrow></math> at DM mass <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>m</mi></mrow><mrow><mi>χ</mi></mrow></msub><mo>≲</mo><msup><mrow><mn>10</mn></mrow><mrow><mn>10</mn></mrow></msup><mtext> </mtext><mtext> </mtext><mi>GeV</mi></mrow></math> for the maximally asymmetric capture rate and show that the constraints persist down to very small values of the cross-section asymmetry, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi mathvariant="script">A</mi><mo>=</mo><mo stretchy="false">(</mo><msub><mrow><mi>σ</mi></mrow><mrow><mi>χ</mi><mi>n</mi></mrow></msub><mo>−</mo><msub><mrow><mi>σ</mi></mrow><mrow><mover accent="true"><mrow><mi>χ</mi></mrow><mrow><mo stretchy="false">˜</mo></mrow></mover><mi>n</mi></mrow></msub><mo stretchy="false">)</mo><mo>/</mo><mo stretchy="false">(</mo><msub><mrow><mi>σ</mi></mrow><mrow><mi>χ</mi><mi>n</mi></mrow></msub><mo>+</mo><msub><mrow><mi>σ</mi></mrow><mrow><mover accent="true"><mrow><mi>χ</mi></mrow><mrow><mo stretchy="false">˜</mo></mrow></mover><mi>n</mi></mrow></msub><mo stretchy="false">)</mo><mo>≳</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>5</mn></mrow></msup></mrow></math>.