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 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.

Brazil

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

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

United States

K. Alfonso

France

A. Armatol

C. Augier

F. Avignone

O. Azzolini

Russia

A. Barabash

G. Bari

A. Barresi

D. Baudin

F. Bellini

G. Benato

L. Benussi

V. Berest

M. Beretta

L. Bergé

M. Bettelli

M. Biassoni

J. Billard

F. Boffelli

V. Boldrini

E. Brandani

C. Brofferio

C. Bucci

M. Buchynska

J. Camilleri

A. Campani

J. Cao

Switzerland

C. Capelli

S. Capelli

V. Caracciolo

L. Cardani

P. Carniti

N. Casali

E. Celi

C. Chang

M. Chapellier

H. Chen

D. Chiesa

D. Cintas

M. Clemenza

I. Colantoni

S. Copello

O. Cremonesi

R. Creswick

A. D’Addabbo

I. Dafinei

Ukraine

F. Danevich

F. Dominicis

M. Jesus

P. Marcillac

S. Dell’Oro

S. Domizio

S. Lorenzo

V. Dompe

A. Drobizhev

L. Dumoulin

G. Fantini

M. El Idrissi

M. Faverzani

E. Ferri

F. Ferri

F. Ferroni

E. Figueroa-Feliciano

J. Formaggio

A. Franceschi

S. Fu

B. Fujikawa

J. Gascon

S. Ghislandi

A. Giachero

M. Girola

L. Gironi

A. Giuliani

P. Gorla

C. Gotti

C. Grant

P. Gras

Germany

P. Guillaumon

T. Gutierrez

K. Han

E. Hansen

K. Heeger

D. Helis

H. Huang

M. Hurst

L. Imbert

A. Juillard

G. Karapetrov

G. Keppel

H. Khalife

V. Kobychev

Yu. Kolomensky

R. Kowalski

H. Lattaud

M. Lefevre

M. Lisovenko

R. Liu

Y. Liu

P. Loaiza

L. Ma

Publisher Erratum: A gravity-based mounting approach for large-scale cryogenic calorimeter arrays

In the framework of a spherically symmetric Friedmann–Lemaître–Robertson–Walker (FLRW) spacetime, we construct a quintessence model driven by a nonlinear, massless spinor field in an open-universe scenario. The model parameters are constrained using recent cosmological observations, including the distance modulus from type Ia supernovae (binned Pantheon sample), Hubble parameter measurements from cosmic chronometers (CC) and the Sloan Digital Sky Survey (SDSS), and baryon acoustic oscillation (BAO) data. A comprehensive Markov chain Monte Carlo (MCMC) analysis yields best-fit estimates for a relatively lower present-day Hubble constant, and the equation-of-state parameter. The best-fit theoretical predictions are compared with observational data for both the Hubble parameter and the distance modulus. Furthermore, the deceleration parameter and the statefinder pair $$\{r, s\}$$ are evaluated to demonstrate the model’s effectiveness in describing the universe’s late-time acceleration. The resulting lower value of $$H_{0}=66.9~\text {km}\,\text {s}^{-1}\,\text {Mpc}^{-1}$$ is consistent with the $\textit{Planck}$ cosmic microwave background (CMB) measurements and suggests a possible route toward alleviating the current Hubble tension. Overall, the spinor field quintessence model with $$w_{\textrm{de}}=-0.814$$ and $$\Omega _{m0} = 0.264$$ emerges as a statistically viable and physically consistent alternative to the standard $$\Lambda $$ CDM cosmology and conventional scalar-field quintessence frameworks.

Mahendra Goray

Bijan Saha

Observational constraints on a nonlinear spinor field quintessence model in an FLRW universe

We formulate a general fusion procedure for open $$\mathfrak{g}\mathfrak{l}(N)$$ spin chains. We construct the fused boundary reflection matrices and the corresponding fused reflection equations. By using the intertwining relation between the fused reflection matrices and the fusion operator, we identify the invariant subspace of the fused reflection matrices carrying the irreducible representations of $$\mathfrak{g}\mathfrak{l}(N)$$ . We also construct the fused transfer matrix and evaluate it explicitly in the total tensor product space and the invariant subspaces. Finally, we demonstrate that the ABJM spin chain model originates from such fusion procedure and derive three classes of boundary reflection matrices solutions on the anti-fundamental representation space of $$\mathfrak{s}\mathfrak{u}(4)$$ .

Nan Bai

A general fusion procedure for open $$\mathfrak{g}\mathfrak{l}(N)$$ spin chains: application to the ABJM spin chain

The dynamical chromoelectric color conductivity of a chiral plasma has been extracted from one loop gluon self energy by using linear response theory at finite temperature and density. It is shown that due to the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>P</mi></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><mi>P</mi></math> violation the conductivity tensor has an anomalous contribution in addition to the longitudinal and transverse components. We identify this anomalous conductivity as chiral chromomagnetic conductivity. The spectral representations of real and imaginary parts of the longitudinal and transverse conductivities show marginal variations in chiral plasma as compared to the nonchiral plasma. The static limit of chiral chromomagnetic conductivity is found to be independent of medium properties reflecting its topological nature.