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)

We propose discussing the modular flavor model and the stabilization of single modulus field in the Jordan frame supergravity with nonminimal scalar-curvature coupling of the form <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">Φ</mi><mo stretchy="false">(</mo><mi>τ</mi><mo>,</mo><mover accent="true"><mi>τ</mi><mo stretchy="false">¯</mo></mover><mo stretchy="false">)</mo><mi>R</mi></math>. Modular invariance, positivity of the scale factor, and positive definiteness of the Kahler metric constrain stringently the form of the frame function, and consequently the Kahler potential by the relation <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">Φ</mi><mo stretchy="false">(</mo><mi>τ</mi><mo>,</mo><mover accent="true"><mi>τ</mi><mo stretchy="false">¯</mo></mover><mo stretchy="false">)</mo><mo>=</mo><mo>−</mo><mn>3</mn><mi>exp</mi><mo stretchy="false">[</mo><mo>−</mo><mi>K</mi><mo stretchy="false">(</mo><mi>τ</mi><mo>,</mo><mover accent="true"><mi>τ</mi><mo stretchy="false">¯</mo></mover><mo stretchy="false">)</mo><mo>/</mo><mn>3</mn><mo stretchy="false">]</mo></math>. We discuss some general properties of scalar potentials after the scale transformation from the Jordan frame to the Einstein frame. We find that the shape of the resulting scalar potential in the Einstein frame is quite different from that of ordinary single modulus stabilization mechanism. The scalar potential could be stationary at the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>i</mi><mi>∞</mi></math> fixed point, leading to a runaway-type vacuum. Such a runaway-type vacuum can be properly stabilized at typical modulus vacuum expectation value with large <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo>ℑ</mo><mi>τ</mi></math>. We also discuss numerically the modulus stabilization for some simplified scenarios.

Fei Wang

Ying Kai Zhang

Modulus stabilization of modular flavor models in Jordan frame supergravity

We present a discovery-era strategy for intensity frontier experiments based on “didecay” events, in which feebly interacting particles (FIPs) are produced in pairs and then both decay inside the detector. This signature may exist in broad classes of models with FIPs decaying in the same way as minimal “portal” particles. The two displaced vertices may allow reconstruction of the pair invariant mass and hence reveal the production channel, information normally inaccessible at these facilities. This, in turn, lets one discriminate between FIP models that share identical decay signatures. As a case study, we consider the model of Higgs-like scalars and show that SHiP, Belle II, and the Downstream@LHCb can each cover wide domains of viable parameter space using didecays.

Germany

Giovani Dalla Valle Garcia

CERN

Maksym Ovchynnikov

Didecay signature of new physics particles at intensity frontier experiments

Several simple asymptotically free chiral gauge theories are studied. The only “free parameters” of our models are the choice of the gauge group, the matter Weyl fermion representations, and the relative magnitudes of the renormalization-group-invariant scales <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi mathvariant="normal">Λ</mi><mi>i</mi></msub></math> associated with each gauge group. None of our models has nontrivial, nonabelian global symmetries (“family-like” fermion representations). We rely on some recent theoretical developments on the dynamics of strongly coupled chiral gauge theories based on the generalized symmetries and associated new types of anomaly matching consideration, but also on the solid knowledge on vector-like gauge theories such as QCD and supersymmetric Yang-Mills theories. The structures of the infrared effective theories, RG flows, and light spectra found in these models are surprisingly rich and intriguing.

Italy

Stefano Bolognesi

Kenichi Konishi

Matteo Orso

Infrared spectra of some strongly-coupled chiral gauge theories

In the present paper, we consider both background dynamic and cosmological perturbations in the framework of modified Gauss–Bonnet gravity model (i.e. $\textit{f}$($\textit{G}$)) which is effective in fitting observational datasets. We assume a specific functional form of it as $$f(G)=\alpha G^{n}$$ , where $$\alpha $$ and $\textit{n}$ are model parameters. After studying the predictions on the expansion history as revealed by CC, CMB, BAO-DESI, Pantheon+SH0ES and Union 3.0 datasets, a suitable constraining of the cosmological parameters has been opted for. We show the linear cosmological perturbations for the full system to investigate the matter fluctuations under the covariant technique. The solutions to the coupled system of perturbation equations are then computed both in long- and short-wavelength modes, in a dust-Gauss–Bonnet fluids system. Using the redshift-space distortion (RSD) datasets consisting of $$f\sigma _8$$ values and MCMC simulations, we present the best-fit cosmological parameters (viz. $$H_0$$ , $$\Omega _{m0}$$ , $$\sigma _8$$ and $\textit{n}$).

Rwanda

Albert Munyeshyaka

India

Praveen Dhankar

Vinod Bhardwaj

Saibal Ray

Joseph Ntahompagaze

Redshift-space distortion in modified Gauss–Bonnet gravity

The bulk of the time required to simulate Cherenkov and scintillation detectors is consumed by optical photon transport, a task that GPUs are uniquely qualified to perform. We present EIC-Opticks, a fork of Opticks, which uses event aggregation to drastically accelerate photon transport simulation for low-to-moderate photon yield experiments. During the full Geant4 Monte Carlo simulation of a given detector, optical photon simulation is performed on GPU(s) using the NVIDIA OptiX framework. We validate this approach using the ePIC pfRICH detector. We find GPU and CPU simulations in excellent agreement, with hit totals agreeing at the $$0.06\%$$ level and wavelength/radial projections giving $$\chi ^2/\textrm{ndf}\simeq 1$$ . At the pfRICH physics program benchmark of $$10^5$$ muons at $$p=5~\textrm{GeV}/c$$ , EIC-Opticks shows $$13.2\pm 0.5\times $$ speedup over 20-thread Geant4 and $$234\pm 10\times $$ over a single thread. In the case of low-to-moderate applications event aggregation reduces the per-photon simulation time from about $$40~\upmu \textrm{s}$$ for single events to about $$20~\textrm{ns}$$ with batching, a factor of about $$2.3\times 10^3$$ . In order to make EIC-Opticks easily installable, we authored a Spack package that makes it possible to install it with a single command. Additionally, a Docker image is provided for users with EIC-Opticks installed. EIC-Opticks provides guardrails for common pitfalls such as deeply nested boolean volumes, maximum-reflection scans, and OptiX ray-origin-offset scans.

United States

Gabor Galgoczi

Kolja Kauder

Maxim Potekhin

Sakib Rahman

Dmitri Smirnov

Torre Wenaus

GPU acceleration of optical photon propagation in low photon yield applications: Opticks for the Electron Ion Collider

In this article, we investigate the observational properties of the Reissner–Nordstr $$\ddot{\textrm{o}}$$ m–Tangherlini (RNT) black hole (BH). Firstly, we briefly explore the spacetime properties of the RNT BH, including the horizon structure and scalar invariants. It was found that the values of the event horizon radius decrease with increasing BH dimension and charge. Subsequently, we explore the massive and massless particle dynamics around RNT BH. Afterwards, gravitational weak lensing is investigated for two plasma types: uniform and non-uniform. Our results show that a uniform plasma increases the deflection angle of light around an RNT BH, whereas a non-uniform plasma decreases it. Finally, we study the BH shadow and constrain the values of the spacetime parameters using the Event Horizon Telescope (EHT) observational results.

Weiqiang Yang

Uzbekistan

Mirzabek Alloqulov

Akbar Davlataliev

Ahmadjon Abdujabbarov

Bobomurat Ahmedov

Chengxun Yuan

Chen Zhou

Observational signature of Reissner–Nordstr $$\ddot{\textrm{o}}$$ m–Tangherlini black hole

The second data release of the Dark Energy Spectroscopic Instrument (DESI DR2) has sharpened the question of whether late-time geometrical observations prefer a departure from the minimal $$\Lambda \textrm{CDM}$$ distance–redshift relation. We examine a deliberately restricted alternative interpretation: whether the same late-time distance information can be absorbed by an effective redshift dependence of the photon propagation factor. We introduce the dimensionless ratio $$C(z)\equiv c(z)/c_0$$ and adopt the bounded one-parameter form $$C(z)=1+\epsilon z/(1+z)$$ , with $$\epsilon =0$$ corresponding to the constant-speed limit. The analysis uses only late-time data: DESI DR2 compressed $$\textrm{BAO}$$ measurements, 31 cosmic-chronometer $$H(z)$$ points, and Type Ia supernova Hubble diagrams from DES-Dovekie and Pantheon-plus. The sound horizon $$r_d$$ is sampled as an independent free parameter with the uniform prior $$r_d\in [120,180]\,\textrm{Mpc}$$ , while the supernova intercept is profiled analytically; no CMB-calibrated sound-horizon prior and no distance-ladder prior are imposed. For the main DES-Dovekie+DESI DR2+ $$H(z)$$ combination we obtain $$\epsilon =-0.096^{+0.125}_{-0.114}$$ . Replacing DES-Dovekie by Pantheon-plus gives $$\epsilon =-0.048^{+0.142}_{-0.122}$$ . The VSL extension improves the minimum $$\chi ^2$$ by only $$1.05$$ relative to flat $$\Lambda \textrm{CDM}$$ , and is penalized by both AIC and BIC. Allowing spatial curvature changes the geometrical degeneracy directions but still gives $$\epsilon $$ consistent with zero. These results show that DESI DR2-era late-time geometry provides a useful null test of cosmological light-speed constancy, but does not support a one-parameter late-time VSL explanation of the DESI geometrical preference.

Shangyun Wang

Shengjia Wang

Late-time varying-speed-of-light test of the DESI DR2 geometrical preference

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

H. Almazan

J.C. dos Anjos

S. Appel

France

J.C. Barriere

I. Bekman

T.J.C. Bezerra

L. Bezrukov

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