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.

China

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

We compute the rate of growth of operator size in matrix models by probing the Lin-Maldacena class of geometries with classical probes. We consider massive point particle probes whose proper momentum equals the size of the gauge invariant operator in the matrix model. We work out the example of the BMN Plane Wave Matrix Model using the electrostatic approach and the method of background fluxes. We also work out complexities in the D2 brane as well as NS5 brane limits of the BMN matrix model along with an example of the irrelevant deformation namely the non-Abelian T-dual of $\textit{AdS}$ × $\textit{S}$ . Finally, we carry out a possible calculation of the Krylov complexity on the matrix model counterpart by using a simple reduction ansatz known as the pulsating fuzzy sphere model. We outline an algorithm to define Krylov basis elements for the matrix model and compute a few Lanczos coefficients. Our analysis reveals that both the Krylov basis states as well as Lanczos coefficients are uniquely fixed in terms of the mass parameter of the matrix model.

India

Dibakar Roychowdhury

Krylov complexity for Lin-Maldacena geometries and their holographic duals

Positive and negative flows of the Chen-Lee-Liu model and its various reductions, including Burgers hierarchy, are formulated within the framework of Riemann-Hilbert-Birkhoff decomposition with the constant grade two generator. Two classes of vacua, namely zero vacuum and constant non-zero vacuum can be realized within a centerless Heisenberg algebra. The tau functions for soliton solutions are obtained by a dressing method and vertex operators are constructed for both types of vacua. We are able to select and classify the soliton solutions in terms of the type of vertices involved. A judicious choice of vertices yields in a closed form a particular set of multi soliton solutions for the Burgers hierarchy. We develop and analyze a class of gauge-Bäcklund transformations that generate further multi soliton solutions from those obtained by dressing method by letting them interact with various integrable defects.

Brazil

Ireland

Y.F. Adans

United States

H. Aratyn

C.P. Constantinidis

J.F. Gomes

G.V. Lobo

T.C. Santiago

New soliton solutions for Chen-Lee-Liu and Burgers hierarchies and its Bäcklund transformations

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.

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 evaluate the Koba-Nielsen-Olesen (KNO) scaling functions for quark- and gluon-initiated jets by incorporating energy conservation into the Double Logarithmic Approximation (DLA). The resulting modified DLA (MDLA) expressions differ substantially from the DLA predictions and qualitatively align with the recently proposed QCD-inspired expressions, albeit with some quantitative differences. By fixing the two parameters in the MDLA expressions, we show that the inclusive charged-particle multiplicity distributions of the two leading jets in $\textit{pp}$ collisions at $$ \sqrt{s}=13 $$ TeV, measured by ATLAS over a wide jet $\textit{p}$ range of 0$\textit{.}$1–2$\textit{.}$5 TeV, are well described within experimental uncertainties and consistent with PYTHIA simulations. This conclusion is further supported by direct comparisons with quark- and gluon-initiated jet distributions extracted via jet topics, though the propagated uncertainties from experimental data remain sizable.

Spain

Xiang-Pan Duan

Lin Chen

Guo-Liang Ma

Carlos Salgado

Bin Wu

Multiplicity distributions in QCD jets and jet topics

Electroweak (EW) amplitudes in the gauge-Goldstone five-component formalism have a distinctive property: gauge symmetry is imprinted in the amplitudes, manifested as the massive Ward identity (MWI) $ k^M{\cal{M}}_M=0 $ . In this study, we used the HELAS package to numerically study gauge symmetry in EW amplitudes. First, we directly tested gauge symmetry by examining the MWI of amplitudes. Second, we modified the couplings within a vertex and among vertices to check if and how the MWI changes. Third, we tested gauge symmetry by considering the couplings modified by operators from the standard model effective field theory (SMEFT). Similar to the standard model, there are relations between different couplings that are protected by gauge symmetry. We observed that, if we modify the couplings to deviate from the relations, the MWI is violated. In contrast, the MWI is restored when the relations between couplings reduce to those in the SMEFT.

Wang-Fa Li

Junmou Chen

Qian-Jiu Wang

Zhao-Huan Yu

Numerical study on the gauge symmetry of electroweak amplitudes * Junmou Chen is supported by National Natural Science Foundation of China (12205118), Wang-Fa Li, Qian-Jiu Wang, and Zhao-Huan Yu are supported by the Guangzhou Science and Technology Planning Project (2024A04J4026)

Recent research has revealed a novel nonlinear mechanism, distinct from the linear superradiant instability, which triggers the black hole bomb phenomenon. Introducing a massive complex scalar field with nonlinear self-interactions drives the Reissner–Nordström black hole to shed substantial energy, thereby triggering a black hole bomb. Radial oscillations in the scalar hair profile are observed during this process. In this paper, we further reveal that physical quantities associated with scalar hair exhibit identical oscillation patterns during the evolution of the black hole-scalar field system. Moreover, the oscillation frequency exhibits a linear dependence on the gauge coupling constant of the scalar field with other parameters fixed. Meanwhile, the horizon radius of hairy black holes and the mass within the horizon increase monotonically with the gauge coupling constant. We have also identified a critical initial charge value that distinguishes hairy solutions that trigger black hole bombs from those that do not.

Lang Zhao

Cheng-Yong Zhang

Radial oscillations of scalar hair in black hole bombs

The Koba-Nielsen-Olesen (KNO) scaling of hadron multiplicity distributions, empirically confirmed to hold approximately in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup></math> collisions and deep inelastic scattering, has been observed to be violated in hadron-hadron collisions. In this work, we show that the universality of KNO scaling can be extended to hadron-hadron collisions when restricted to QCD jets. We present a comprehensive study of KNO scaling in QCD jets produced in proton-proton collisions at the LHC. Using perturbative QCD calculations in the double logarithmic approximation and pythia simulations, we find that KNO scaling approximately holds for both quark and gluon jets across a broad jet <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>p</mi><mi>T</mi></msub></math> range, from 0.1 to 2.5 TeV, at both the parton and hadron levels. Especially, we highlight characteristic differences between the KNO scaling functions of quark and gluon jets, with the quark-jet scaling function lying above that of gluon jets at both low and high multiplicities. This distinction is essential for interpreting inclusive jet data at the LHC. Furthermore, we propose direct experimental tests of KNO scaling in QCD jets at the LHC through quark-gluon discrimination using jet substructure techniques, as demonstrated by applying energy correlation functions to pythia-generated data.

Carlos A. Salgado

Koba-Nielsen-Olesen scaling in quark and gluon jets at the LHC

We present a systematic investigation of lepton pair production through photon-photon fusion processes in heavy-ion collisions. It is demonstrated that the dilepton production at a given impact parameter ( <math altimg='si1.svg'><msub><mrow><mi>b</mi></mrow><mrow><mo>&#8869;</mo></mrow></msub></math>) with a fixed transverse momentum imbalance ( <math altimg='si2.svg'><msub><mrow><mi>q</mi></mrow><mrow><mo>&#8869;</mo></mrow></msub></math>) can be factorized into a unified formula in terms of the Wigner photon distribution of heavy nuclei. We show that this framework provides a comprehensive description of all the relevant data from RHIC to the LHC, with a strong evidence that the quasi-real photon can be radiated not only from the nucleus as a whole, standing for the coherent contribution, but also from the sub-structures inside the nucleus, representing the incoherent contribution. Further predictions are made for the anisotropies in the correlations between <math altimg='si2.svg'><msub><mrow><mi>q</mi></mrow><mrow><mo>&#8869;</mo></mrow></msub></math>, <math altimg='si1.svg'><msub><mrow><mi>b</mi></mrow><mrow><mo>&#8869;</mo></mrow></msub></math>, and the dilepton transverse momentum ( <math altimg='si3.svg'><msub><mrow><mi>P</mi></mrow><mrow><mo>&#8869;</mo></mrow></msub></math>). This will help us to constrain the photon Wigner distribution which plays a crucial role to study the gluonic matter of nucleus at small- <italic>x</italic> through the diffractive photoproduction processes in heavy ion collision.

France

Yu Shi

Hong Kong

Shu-Yi Wei

Bo-Wen Xiao

Lighting up the photon Wigner distribution via dilepton productions

The attenuation length of the muon content in extensive air showers provides important information regarding the generation and development of air showers. This information can be used not only to improve the description of such showers but also to test fundamental models of hadronic interactions. Using data from the LHAASO-KM2A experiment, the development of the muon content in high-energy air showers was studied. The attenuation length of muon content in the air showers was measured from experimental data in the energy range from 0.3 to 30 PeV using the constant intensity cut method. By comparing the attenuation length of the muon content with predictions from high-energy hadronic interaction models (qgsjet-II-04, sibyll 2.3d, and epos-lhc), it is evident that LHAASO results are significantly shorter than those predicted by the first two models (qgsjet-II-04 and sibyll 2.3d) but relatively close to those predicted by the third model (epos-lhc). Thus, the LHAASO data favor the epos-lhc model over the other two models. The three interaction models confirmed an increasing trend in the attenuation length as the cosmic-ray energy increases.

Zhen Cao

Germany

F. Aharonian

 Axikegu

Y. X. Bai

Y. W. Bao

D. Bastieri

X. J. Bi

Y. J. Bi

W. Bian

Russia

A. V. Bukevich

Q. Cao

W. Y. Cao

Zhe Cao

J. Chang

J. F. Chang

A. M. Chen

E. S. Chen

H. X. Chen

Liang Chen

Long Chen

M. J. Chen

M. L. Chen

Q. H. Chen

S. Chen

S. H. Chen

S. Z. Chen

T. L. Chen

Y. Chen

N. Cheng

Y. D. Cheng

M. C. Chu

M. Y. Cui

S. W. Cui

X. H. Cui

Y. D. Cui

B. Z. Dai

H. L. Dai

Z. G. Dai

 Danzengluobu

X. Q. Dong

K. K. Duan

J. H. Fan

Y. Z. Fan

J. Fang

J. H. Fang

K. Fang

C. F. Feng

H. Feng

L. Feng

S. H. Feng

X. T. Feng

Y. Feng

Y. L. Feng

S. Gabici

B. Gao

C. D. Gao

Q. Gao

W. Gao

W. K. Gao

M. M. Ge

T. T. Ge

L. S. Geng

G. Giacinti

G. H. Gong

Q. B. Gou

M. H. Gu

F. L. Guo

J. Guo

X. L. Guo

Y. Q. Guo

Y. Y. Guo

Y. A. Han

O. A. Hannuksela

M. Hasan

H. H. He

H. N. He

J. Y. He

Y. He

Y. K. Hor

B. W. Hou

C. Hou

X. Hou

H. B. Hu

Q. Hu

S. C. Hu

C. Huang

D. H. Huang

T. Q. Huang

W. J. Huang

X. T. Huang

X. Y. Huang

Y. Huang

Y. Y. Huang

X. L. Ji

H. Y. Jia

K. Jia

H. B. Jiang

K. Jiang

X. W. Jiang

Measurement of attenuation length of the muon content in extensive air showers from 0.3 to 30 PeV with LHAASO