We study a three-loop induced neutrino mass scenario from a non-holomorphic modular $\textit{A}$ $_{4}$ flavor symmetry and obtain the minimum scenario leading to predictions of the lepton masses, mixing angles, and Dirac and Majorana phases, which are shown through chi square analyses. In addition, we discuss the lepton flavor violations, muon anomalous magnetic moment, lepton universality, and relic density of the dark matter candidate. Moreover, we show that our model can be extended to satisfy the observed relic density of dark matter within the limit of perturbation by adding one singlet scalar boson without changing predictions in the neutrino sector.

China

Takaaki Nomura

Hiroshi Okada

Neutrino mass model at a three-loop level from a non-holomorphic modular $\textit{A}$ $_{4}$ symmetry * Takaaki Nomura is supported by the Fundamental Research Funds for the Central Universities. Hiroshi Okada is supported by Zhongyuan Talent (Talent Recruitment Series) Foreign Experts Project

We present an exact analytical study of null trajectories and scalar wave propagation in a $$(2+1)$$ -dimensional spacetime containing a spiral dislocation, a topological defect characterized by torsion in the absence of curvature. For null rays, the torsion parameter $$\beta $$ modifies the affine structure, enforcing a finite turning radius $$r_{\min } = \sqrt{b^2 - \beta ^2}$$ , and inducing a torsion-mediated angular deflection that decreases monotonically with increasing $$\beta $$ . The photon trajectory departs from the curvature-induced lensing paradigm, exhibiting instead a purely topological exclusion zone around the defect core. Moreover, the results can, in principle, be mapped onto laboratory frames and conditions. In the wave regime, we recast the Helmholtz equation into a Schrödinger-like form and extract a spatially and spectrally dependent refractive index $$n^2(r,k)$$ . This index approaches unity asymptotically at large distances but diverges strongly and negatively near the dislocation core due to torsion-induced geometric contributions. The resulting refractive index profile governs the transition from propagating to evanescent wave behavior, with low-frequency modes undergoing pronounced localization and suppression. Our findings demonstrate that torsion alone, even in the absence of curvature, can act as a geometric regulator of both classical and quantum propagation, inducing effective anisotropy, frequency filtering, and confinement. This framework provides a rare exact realization of light-matter interaction in a torsion-dominated background, with potential applications in analog gravity systems and photonic metamaterials designed to emulate non-Riemannian geometries.

Türkiye

Semra Gurtas Dogan

Omar Mustafa

Abdullah Guvendi

Czechia

Spain

Azerbaijan

Hassan Hassanabadi

Optics in spiral dislocation spacetime: torsion as a geometric waveguide and frequency-filtering mechanism

SPARKX is an open-source Python package developed to analyze simulation data from heavy-ion collision experiments. By offering a comprehensive suite of tools, SPARKX simplifies data analysis workflows, supports multiple formats such as OSCAR2013, and integrates seamlessly with SMASH and JETSCAPE/X-SCAPE. This paper describes SPARKX’s architecture, features, and applications and demonstrates its effectiveness through detailed examples and performance benchmarks. SPARKX enhances productivity and precision in relativistic kinematics studies.

Germany

Nils Sass

United States

Hendrik Roch

Niklas Götz

Renata Krupczak

Carl Rosenkvist

SPARKX: a software package for analyzing relativistic kinematics in collision experiments

Using functional integral methods, we investigate the non-Abelian Casimir energy in the Curci-Ferrari model, which offers an effective description of the infrared regime of Yang-Mills theory. We consider a 3+1D (resp. 2+1D) system of two infinite parallel plates (resp. wires) at a fixed distance from each other, with either perfect magnetic conductor (PMC) or perfect electric conductor (PEC) boundary conditions. Imposing the boundary conditions directly in the functional integral by the introduction of suitable auxiliary fields that act as Lagrange multipliers, we obtain a boundary effective action that captures the dynamics of this system. The Casimir energy is then computed both directly from the functional integral and via the energy-momentum tensor, providing equivalent results. We find that the Casimir energy for PEC and PMC conditions differs by a constant factor, which can be traced back to a van Dam-Veltman-Zakharov-like discontinuity (both in 3+1D and 2+1D). Lastly, we show that our analytical results are compatible with a variety of recent numerical lattice simulations of the non-perturbative Yang-Mills Casimir energy, in which a novel non-perturbative mass scale emerges.

Belgium

David Dudal

Brazil

Philipe Fabritiis

Sebbe Stouten

Non-Abelian Casimir energy in the Curci-Ferrari model through a functional approach

We propose a unified framework for dark matter and dark energy based on the thermodynamic properties of a degenerate, relativistic Fermi gas in a higher-dimensional space-time. Extending the standard equation of state to $\textit{D}$-dimensional space-time, we derive analytical expressions for the energy density, pressure, number density, sound velocity, and polytropic indices of a zero-temperature Fermi gas. Remarkably, we show that in the limit of vanishing Fermi momentum, the system exhibits a negative vacuum pressure and positive energy density when $$D=(5+4n)$$ , with $$n\in \mathbb {N}$$ . This feature provides a natural mechanism for the emergence of a cosmological constant-like component from fermionic matter in extra dimensions. In this context, dark matter arises from the bulk fermions’ rest mass energy, while dark energy emerges from their vacuum contributions. The observed cosmological vacuum energy density can be matched by fixing the compactification length scale, leading to constraints that depend on the fermion mass and the number of extra dimensions. Our results suggest that the dark sector may originate from a common fermionic source embedded in a higher-dimensional space-time, offering a novel pathway toward the unification of dark matter and dark energy.

G. Carvalho

Italy

R. Lobato

R. Marinho

M. Malheiro

Unifying dark matter and dark energy as a Fermi gas in extra dimensions

Though investigated extensively in the past, we take a detailed relook at the study of quasinormal modes (QNM) in a known family of wormholes (ultrastatic ( $$g_{00}=-1$$ ), as well as spacetimes with different, non-constant $$g_{00}$$ ), which includes the familiar Bronnikov–Ellis spacetime as a special case. Our focus here is to go beyond the fundamental mode and obtain some of the QNM overtones using a suitable numerical scheme. Scalar and axial gravitational QNMs including two or three overtones are obtained for the family of ultrastatic geometries and their parameter dependencies are shown explicitly. Further, we comment on how (a) the overtones may influence the time-domain profile in a perturbation and (b) in what sense, the use of overtones may help in distinguishing between different geometries within the family. Finally, we show how an effect somewhat similar to the so-called ‘environment induced redshift’ of QNMs, introduced recently (Pezzella et al. in Phys Rev D 111:064026, 2025), may be obtained for spacetimes with non-constant $$g_{00}$$ , via an appropriate tuning of available metric parameters which systematically modify the shapes of the effective potentials arising in the perturbation equations.

India

Abhisek Maji

Sayan Kar

Quasinormal spectra of a wormhole family: overtone features and a parameter-controlled redshift

The degradation of quantum resources due to environmental noise is a fundamental challenge in quantum information science. In relativistic settings, this noise is intrinsically linked to vacuum fluctuations. Here, we investigate this connection using a model of two Unruh-DeWitt detectors interacting with a scalar field in Minkowski spacetime. Specifically, we focus on Bell nonlocality, quantum coherence, the nonlocal advantage of quantum coherence, and measured uncertainty, examining their dependence on the detector-field energy ratio, the inter-detector distance, and the initial state parameter. Notably, our central finding is that vacuum fluctuations are the primary mechanism of decoherence. Moreover, while spatial separation induces decoherence, all quantum resources converge to a non-zero steady state at large distances, confirming the robustness of nonlocality. These insights provide a deeper understanding of quantumness in a relativistic framework and may contribute to the ongoing discussion on the black hole information paradox.

Yu-Kun Zhang

Tariq Aziz

Li-Juan Li

Xue-Ke Song

Liu Ye

Dong Wang

Quantumness and entropic uncertainty for a pair of static Unruh-DeWitt detectors

We consider a simple Higgs portal dark matter (DM) model, where the Standard Model is extended with a complex singlet scalar. The imaginary part of the scalar becomes a massive and stable pseudo-Nambu-Goldstone boson, serving as the DM candidate, while the real part gives rise to a second (dark) Higgs boson. We focus on the freeze-in production of the DM, paying particular attention to low-reheating temperature scenarios, where the dark Higgs can be a long-lived particle (LLP). We also explore the phenomenology of this dark Higgs at the LHC and the Future Circular Collider in hadron-hadron mode, discussing its discovery prospects in regions of parameter space consistent with current DM constraints. Our results emphasize the impact of the cosmic reheating dynamics on the DM freeze-in production, and their critical role in interpreting collider signatures. Furthermore, our findings suggest that LLP searches may provide insights into the fundamental dynamics of reheating.

United Arab Emirates

Nicolás Bernal

Chile

Giovanna Cottin

Bastián Díaz Sáez

Manuel López

Testing frozen-in pNGB dark matter with a long-lived dark Higgs

Recent computations in gravity suggest that nonsupersymmetric extremal black holes lack any sizeable ground state degeneracy. We confirm this for a D-brane description of nonsupersymmetric four-charge extremal black holes in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi mathvariant="normal">N</mi><mo>=</mo><mn>8</mn></mrow></math> string theory. The microscopic description comprises four stacks of D-branes wrapping various cycles of the internal six torus and intersecting at a point. The orientations of the stacks are such that supersymmetry is broken completely. We construct the low energy worldline Lagrangian for the brane system, which is seen to have 32 Goldstinos and 28 Goldstones. The Hamiltonian has a unique ground state, which carries a nonzero energy implying the absence of any truly extremal state. Our arguments rely on symmetry and hence should hold in the supergravity regime as well.

Ireland

Swapnamay Mondal

Extremal black hole with a unique ground state

A recent independent dark photon (DP) focused reanalysis of existing data from the TASEH axion haloscope experiment reported a tentative DP dark matter signal with local significance <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo>∼</mo><mn>4.7</mn><mi>σ</mi></math> at a frequency <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>f</mi><mo>≈</mo><mn>4.71</mn><mtext> </mtext><mtext> </mtext><mrow><mi>GHz</mi></mrow></mrow></math>, corresponding to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>m</mi></mrow><mrow><mi>X</mi></mrow></msub><mo>≈</mo><mn>19.5</mn><mtext> </mtext><mtext> </mtext><mi mathvariant="normal">μ</mi><mi>eV</mi></mrow></math> and kinetic mixing <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>ϵ</mi><mo>∼</mo><mn>6.5</mn><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>15</mn></mrow></msup></mrow></math>. Motivated by this report, we performed a dedicated, narrowband follow-up experiment to confirm or refute the signal with a cryogenic microwave cavity operated without a magnetic field, leveraging the ORGAN-Q dilution refrigeration and receiver chain. Scanning a window centered on the reported frequency over a live time of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>T</mi><mi>int</mi></msub><mo>∼</mo><mn>13</mn><mtext> </mtext><mtext> </mtext><mi>days</mi></math>, we find no excess consistent with a dark photon signal as reported, and set a 95% CL of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>ϵ</mi><mo>≤</mo><mn>5.04</mn><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>15</mn></mrow></msup></mrow></math> in a narrow mass range around <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo>∼</mo><mn>19.5</mn><mtext> </mtext><mtext> </mtext><mi mathvariant="normal">μ</mi><mi>eV</mi></math>, excluding a signal of the strength and frequency reported to 99.92% confidence. We discuss the experiment and present the exclusion limits.

Australia

Aaron P. Quiskamp

Graeme R. Flower

Maxim Goryachev

Michael E. Tobar

Ben T. McAllister

Follow-up search for a tentative dark photon signal near <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>19.5</mn><mtext> </mtext><mtext> </mtext><mi mathvariant="normal">μ</mi><mi>eV</mi></mrow></math> using the ORGAN-Q infrastructure