We investigate the frame dependence of distribution functions within the framework of generalized chiral kinetic theory. Based on the derived transformation rules governing the choice of frame, we analytically obtain the global equilibrium solutions in the presence of vorticity and electromagnetic fields. Our results show that, under the assumption of varying electromagnetic fields, these equilibrium solutions can be uniquely determined.

China

Shu-Xiang Ma

Jian-Hua Gao

Frame dependence in generalized chiral kinetic theory * Supported in part by the National Natural Science Foundation of China (12575147, 12321005, 12175123)

This work sets out to compute the corrections to the Euler-Heisenberg effective action that arise from spacetime-dependent background anisotropies that violate Lorentz symmetry. To accomplish our task, we evaluate the functional determinant of the modified Dirac operator using the spectral regularization method. Within the framework of the Standard Model extension (SME), these Lorentz-violating parameters correspond to the coefficients <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>m</mi><mn>5</mn></msub><mo stretchy="false">(</mo><mi>x</mi><mo stretchy="false">)</mo></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>a</mi><mi>μ</mi></msub><mo stretchy="false">(</mo><mi>x</mi><mo stretchy="false">)</mo></math>, and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>b</mi><mi>μ</mi></msub><mo stretchy="false">(</mo><mi>x</mi><mo stretchy="false">)</mo></math>. The corrected effective action is attained up to the second-order in the background parameters. Our results indicate a violation of Furry’s theorem at second-order for specific C-odd combinations of these parameters, in agreement with previous analyses based on explicit Feynman diagram calculations in scenarios with Lorentz-symmetry violation. In the kinetic (bilinear) piece of the effective action, nondynamical axionlike terms emerge, resembling structures commonly encountered in condensed-matter systems, such as Weyl semimetals. We show how this procedure modifies the Maxwell equations, from which we present both the corresponding (non)conservation of the energy-momentum tensor and the wave equation. We also notice that the vacuum behaves as an inhomogeneous medium, and compute the local dispersion relation by working in the eikonal approximation. As a result of the spacetime-dependence of the background, there appear imaginary contributions in the dispersion relation and, consequently, the wave amplitudes may be amplified or attenuated, which expresses the energy-momentum exchange between the waves and the background.

Brazil

Wagno Cesar e Silva

João Paulo S. Melo

José A. Helayël-Neto

Extending the Euler-Heisenberg action to include effects of local Lorentz-symmetry violating backgrounds

Neutrino emission from nuclear reactors provides real-time insights into reactor power and fuel evolution, with potential applications in monitoring and nuclear safeguards. Following reactor shutdown, a low-intensity flux of “residual neutrinos” persists due to the decay of long-lived fission isotopes in the partially burnt fuel remaining within the reactor cores and in spent nuclear fuel stored in nearby cooling pools. The Double Chooz experiment at the Chooz B nuclear power plant in France achieved the first quantitative measurement of this residual flux based on 17.2 days of reactor-off data. In the energy range where the residual signal is most pronounced, the neutrino detector located 400 m from the cores recorded <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>106</mn><mo>±</mo><mn>18</mn></math> neutrino candidate events (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>5.9</mn><mi>σ</mi></mrow></math> significance). This measurement is in excellent agreement with the predicted value of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>88</mn><mo>±</mo><mn>7</mn></math> events derived from detailed reactor simulations modeling the decay activities of fission products and incorporating the best-available models of neutrino spectra.

T. Abrahão

Germany

H. Almazan

J.C. dos Anjos

S. Appel

France

J.C. Barriere

I. Bekman

T.J.C. Bezerra

L. Bezrukov

United States

E. Blucher

C. Bourgeois

C. Buck

J. Busenitz

A. Cabrera

Spain

M. Cerrada

E. Chauveau

P. Chimenti

O. Corpace

J.V. Dawson

J.F. Du

Z. Djurcic

A. Etenko

Japan

H. Furuta

I. Gil-Botella

A. Givaudan

H. Gomez

M.C. Goodman

T. Hara

J. Haser

D. Hellwig

A. Hourlier

M. Ishitsuka

J. Jochum

C. Jollet

K. Kale

M. Kaneda

M. Karakac

T. Kawasaki

E. Kemp

D. Kryn

M. Kuze

T. Lachenmaier

C.E. Lane

T. Lasserre

D. Lhuillier

H.P. Lima

M. Lindner

J.M. LoSecco

B. Lubsandorzhiev

J. Maeda

C. Mariani

J. Maricic

J. Martino

T. Matsubara

G. Mention

A. Meregaglia

T. Miletic

R. Milincic

A. Minotti

X. Mougeot

D. Navas-Nicolás

Y. Nikitenko

P. Novella

L. Oberauer

M. Obolensky

A. Onillon

A. Oralbaev

C. Palomares

I.M. Pepe

L. Perisse

G. Pronost

J. Reichenbacher

S. Schönert

S. Schoppmann

L. Scola

R. Sharankova

V. Sibille

V. Sinev

M. Skorokhvatov

P. Soldin

A. Stahl

I. Stancu

M.R. Stock

L.F.F. Stokes

F. Suekane

S. Sukhotin

T. Sumiyoshi

C. Veyssiere

B. Viaud

M. Vivier

S. Wagner

C. Wiebusch

G. Yang

F. Yermia

First Measurement of Neutrino Emissions from Spent Nuclear Fuel by the Double Chooz Experiment

The matrix element in the proton of the eikonal Odderon operator, with a helicity flip, has been shown to correspond to the dipole gluon Sivers function. We employ a three quark light-front model of the proton to determine the Sivers function at moderately small <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>x</mi><mn>0</mn></msub><mo>∼</mo><mn>0.1</mn></math> and transverse momentum <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>k</mi><mo>⊥</mo></msub><mo>≲</mo><mn>1</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi></math>. The model light-cone (LC) wave function predicts the properties of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>x</mi><msubsup><mi>f</mi><mrow><mn>1</mn><mi>T</mi></mrow><mrow><mo>⊥</mo><mi>g</mi></mrow></msubsup><mo stretchy="false">(</mo><mi>x</mi><mo>,</mo><msub><mi>k</mi><mo>⊥</mo></msub><mo stretchy="false">)</mo></math> such as its overall magnitude, the position of its peak in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>k</mi><mo>⊥</mo></msub></math>, and its behavior at small <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>k</mi><mo>⊥</mo></msub></math>. We then compute numerically the Balitsky-Fadin-Kuraev-Lipatov anomalous dimension characterizing the power-law tail at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>k</mi><mo>⊥</mo></msub><mo>≳</mo><mn>1.5</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi></math> of the gluon Sivers function at small (but preasymptotic) LC momentum fractions <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>x</mi><mo>∼</mo><msub><mi>x</mi><mn>0</mn></msub><msup><mi>e</mi><mrow><mo>−</mo><mn>1</mn><mo>/</mo><msub><mi>α</mi><mi>s</mi></msub></mrow></msup></math>: <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>x</mi><msubsup><mi>f</mi><mrow><mn>1</mn><mi>T</mi></mrow><mrow><mo>⊥</mo><mi>g</mi></mrow></msubsup><mo stretchy="false">(</mo><mi>x</mi><mo>,</mo><msub><mi>k</mi><mo>⊥</mo></msub><mo stretchy="false">)</mo><mo>∼</mo><msubsup><mi>k</mi><mo>⊥</mo><mrow><mo>−</mo><mn>3.3</mn></mrow></msubsup></math>.

Croatia

Sanjin Benić

Adrian Dumitru

Florian Hechenberger

Poland

Tomasz Stebel

Eikonal spin-dependent odderon and gluon Sivers function of a proton and its small-<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>x</mi></math> evolution

Lepton-flavor-violating (LFV) interactions involving dark matter (DM) particles remain a largely unexplored area. In this study, we systematically investigate LFV DM interactions within the framework of effective field theories by analyzing astrophysical photons and positrons produced from DM annihilation. Employing the astrophysical photon and positron data collected by Fermi-LAT, INTEGRAL, XMM-Newton, and AMS-02, we place meaningful constraints on all leading-order effective operators involving a DM pair and a flavor-violating charged lepton pair. Our analysis covers the three well-known DM candidates: a scalar, a fermion, and a vector particle. For the photon flux, we consider contributions from final-state radiation, radiative decay, and inverse Compton scattering and examine their respective sensitivity regions across different DM masses and photon energies. We find that, for DM masses below <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">O</mi><mo stretchy="false">(</mo><mn>20</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi><mo stretchy="false">)</mo></math>, INTEGRAL provides the most stringent constraints on annihilation cross sections and effective operators in all three LFV channels, whereas AMS-02 offers the strongest constraints above <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">O</mi><mo stretchy="false">(</mo><mn>20</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi><mo stretchy="false">)</mo></math>.

Sahabub Jahedi

Jin-Han Liang

Yi Liao

Xiao-Dong Ma

Yoshiki Uchida

Systematic study of lepton-flavor-violating dark matter interactions via indirect detection in effective field theories

The Laser Interferometer Space Antenna (LISA) is a space-based gravitational-wave observatory that uses free-falling test masses as inertial references to detect mHz-frequency signals. Interactions between these test masses and galactic or solar energetic particles cause charge buildup and Coulomb forces, a major source of acceleration noise that must be accurately modeled. LISA Pathfinder measurements showed that the Poissonian test-mass charging noise, an important entry in the noise budget, was considerably larger than that in prelaunch simulations, indicating missing physical processes in early models. Emission of low-energy secondary electrons (LEEs) from test-mass and housing surfaces has been proposed as a key mechanism affecting charging and the sensor’s electrostatic response. We report a particle accelerator-based experiment that directly tests the LEE hypothesis by measuring proton-induced test-mass charging in a LISA-like Gravitational Reference Sensor geometry as a function of the test-mass electrostatic potential. A flight-representative test mass and the capacitive sensor electrode housing surrounding it are exposed in vacuum to monoenergetic 70–230 MeV proton beams, while test-mass charging currents are measured with femtoampere sensitivity. By varying the test-mass potential by volts during irradiation, we gain sensitivity to eV-scale charge carriers whose transport and collection depend on these fields. The measurements yield stable, reproducible picoampere-level charging currents and a clear dependence of the net charging rate on test-mass potential. This behavior directly supports the role of low-energy secondary electrons in test-mass charging and is consistent with the LEE-based interpretation of LISA Pathfinder data. These are the first controlled laboratory measurements of low-energy electron effects in test-mass charging for a LISA-like sensor and provide a benchmark for validating charging models and charge-management strategies for LISA and future space-based precision interferometry missions.

Italy

Francesco Dimiccoli

Francesco Venturelli

Valerio Ferroni

Antonella Cavalleri

Teodoro Klaser

Matteo Tomasi

Davide Dal Bosco

Enrico Verroi

Rita Dolesi

William J. Weber

Observations of low-energy-electron production and experimental characterization of the test-mass charging process in the LISA gravitational reference sensor with the BART experiment

The gauge principle is a cornerstone of particle-physics model building. Nevertheless, many constructions leave certain global <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>U</mi><mo stretchy="false">(</mo><mn>1</mn><mo stretchy="false">)</mo></math> redundancies ungauged. In this work, we take the gauge principle to its logical extreme by promoting all <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>S</mi><mi>U</mi><mo stretchy="false">(</mo><mi>N</mi><mo stretchy="false">)</mo></math> symmetries to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>U</mi><mo stretchy="false">(</mo><mi>N</mi><mo stretchy="false">)</mo></math>. We focus on a model based on local <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>U</mi><mo stretchy="false">(</mo><mn>3</mn><mo stretchy="false">)</mo><mo>×</mo><mi>U</mi><mo stretchy="false">(</mo><mn>2</mn><mo stretchy="false">)</mo></math> invariance. This framework accounts for several otherwise ad hoc features of the Standard Model, including charge quantization and the observed hypercharge assignments, which emerge here as unique predictions. Furthermore, the internal consistency of the model requires the introduction of right-handed neutrinos and implies the presence of an additional <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>U</mi><mo stretchy="false">(</mo><mn>1</mn><mo stretchy="false">)</mo></math> factor that can be identified with <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi><mo>−</mo><mi>L</mi></math>, thereby naturally yielding nonzero neutrino masses. In light of these findings, we hypothesize that <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>U</mi><mo stretchy="false">(</mo><mn>3</mn><mo stretchy="false">)</mo><mo>×</mo><mi>U</mi><mo stretchy="false">(</mo><mn>2</mn><mo stretchy="false">)</mo></math> constitutes the underlying symmetry of the strong and electroweak interactions. More importantly, our approach opens up novel avenues for model building, driven by this extended interpretation of the gauge principle.

Antonio Herrero-Brocal

Javier Perez-Soler

Avelino Vicente

Beyond <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>S</mi><mi>U</mi><mo stretchy="false">(</mo><mi>N</mi><mo stretchy="false">)</mo></math>: <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>U</mi><mo stretchy="false">(</mo><mn>3</mn><mo stretchy="false">)</mo><mo>×</mo><mi>U</mi><mo stretchy="false">(</mo><mn>2</mn><mo stretchy="false">)</mo></math> as the underlying symmetry of the strong and electroweak interactions

We study thermodynamic topological classes of $\textit{d}$-dimensional Reissner–Nordström (RN) black holes in a cavity at fixed charge. Starting from the reduced Euclidean action, we use the quasilocal energy, entropy, and on-shell inverse temperature to construct the off-shell vector field. The central question is which boundary thermodynamic quantities, rather than which local branch formulas, determine the refined thermodynamic topological class. A finite cavity gives two charge dependent classes: neutral black holes belong to $$W^{0-}$$ , whereas charged black holes belong to $$W^{1+}$$ . If the cavity radius is sent to infinity at fixed physical charge, the endpoint thermodynamic quantities change, giving $$W^{1-}$$ for the neutral case and $$W^{0+}$$ for the charged case. Thus the electric charge and the outer boundary, rather than the spacetime dimension in the explicit four- and five-dimensional examples, determine the refined topological class within this RN cavity family. The result identifies the cavity wall as part of the endpoint thermodynamic input entering the boundary degree, not merely as a thermodynamic regulator.

Rongrong Zhai

Endpoint control of thermodynamic topological classes for fixed charge $\textit{d}$-dimensional Reissner–Nordström black holes in a cavity

Determining whether Planck-scale effects can stabilize black holes addresses fundamental questions about black hole evaporation and quantum gravity consistency. Here, we analyze the thermodynamic topology ofSchwarzschild black holes under Planck-scale modified kinematics, using a cubic entropy correction derived from a well-known phenomenological MDR with leading correction $$\eta E^3/E_P$$ . Enforcing physical constraints ( $$S'(r_h) > 0$$ , $$T > 0$$ ) via the entropy-geometry correspondence, we find a single unstable branch with $$w = -1$$ and $$W = -1$$ for both signs of the correction parameter. A second root suggesting stability ( $$w = +1$$ ) is excluded due to negative mass/temperature and lies outside the perturbative regime. Thus, this class of MDRs does not yield stable Schwarzschild black holes. However, MDRs with different leading-order corrections may behave otherwise, leaving the search for Planck-scale stabilization an open endeavor.

Iran

Azerbaijan

Mohsen Khodadi

Kazakhstan

Nosratolla Jafari

Shahin Mamedov

A winding number analysis of Schwarzschild black hole stability in light of Planck-scale modified kinematics

In this study, we explore the cosmological evolution of the Universe in the framework of covariant $\textit{f}$($\textit{Q}$) gravity, with a coupling function that evolves dynamically in proportion to the Hubble parameter. Two specific forms of the function are examined: a power-law model and a logarithmic model. By rewriting the cosmological field equations as an autonomous dynamical system, we determine and classify the corresponding critical points and analyze their stability. Our results show that both models are able to reproduce the sequence of cosmic evolution, including radiation, matter, and dark energy-dominated eras, along with the transitions between them. The physical properties at each critical point are described using key cosmological quantities such as the total EoS parameter, density parameters, and the deceleration parameter. The stability of the non-hyperbolic critical point is analyzed through center manifold theory. In addition, we present phase space trajectories along with the stability behavior of each critical point. The evolution plots for the density parameters of radiation, matter, and dark energy, along with the Equation of State (EoS) parameter for the total, are illustrated for further analysis. Overall, the analysis suggests that the $\textit{f}$($\textit{Q}$) models considered here, within the context of covariant formulation, provide a consistent description of cosmic evolution and offer a promising approach to explaining the late-time acceleration of the Universe.

India

S. Narawade

S. Kadam

Dynamical analysis of the covariant $\textit{f}$($\textit{Q}$) gravity models