<p>Recent measurements of charmed-baryon semileptonic decays signal large tensions between experiment and theory, including <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>S</mi><mi>U</mi><mo stretchy="false">(</mo><mn>3</mn><msub><mo stretchy="false">)</mo><mi>F</mi></msub></math> analyses and lattice-quantum chromodynamics simulations. Possible sources of the discrepancy include the experimental normalization mode <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi mathvariant="normal">Ξ</mi><mi>c</mi><mn>0</mn></msubsup><mo stretchy="false">→</mo><msup><mi mathvariant="normal">Ξ</mi><mo>−</mo></msup><msup><mi>π</mi><mo>+</mo></msup></math>. Using lattice-quantum chromodynamics inputs in an <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>S</mi><mi>U</mi><mo stretchy="false">(</mo><mn>3</mn><msub><mo stretchy="false">)</mo><mi>F</mi></msub></math> analysis including first-order symmetry breaking, we predict <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">B</mi><mo stretchy="false">(</mo><msubsup><mi mathvariant="normal">Ξ</mi><mi>c</mi><mo>+</mo></msubsup><mo stretchy="false">→</mo><msup><mi mathvariant="normal">Σ</mi><mn>0</mn></msup><msup><mo>ℓ</mo><mo>+</mo></msup><msub><mi>ν</mi><mo>ℓ</mo></msub><mo stretchy="false">)</mo><mo>/</mo><mi mathvariant="script">B</mi><mo stretchy="false">(</mo><msubsup><mi mathvariant="normal">Ξ</mi><mi>c</mi><mo>+</mo></msubsup><mo stretchy="false">→</mo><msup><mi mathvariant="normal">Ξ</mi><mn>0</mn></msup><msup><mo>ℓ</mo><mo>+</mo></msup><msub><mi>ν</mi><mo>ℓ</mo></msub><mo stretchy="false">)</mo><mo>=</mo><mo stretchy="false">(</mo><mn>2.6</mn><mo>±</mo><mn>0.3</mn><mo stretchy="false">)</mo><mo>%</mo></math>, and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">B</mi><mo stretchy="false">(</mo><msubsup><mi mathvariant="normal">Ξ</mi><mi>c</mi><mo>+</mo></msubsup><mo stretchy="false">→</mo><mi mathvariant="normal">Λ</mi><msup><mo>ℓ</mo><mo>+</mo></msup><msub><mi>ν</mi><mo>ℓ</mo></msub><mo stretchy="false">)</mo><mo>/</mo><mi mathvariant="script">B</mi><mo stretchy="false">(</mo><msubsup><mi mathvariant="normal">Ξ</mi><mi>c</mi><mo>+</mo></msubsup><mo stretchy="false">→</mo><msup><mi mathvariant="normal">Ξ</mi><mn>0</mn></msup><msup><mo>ℓ</mo><mo>+</mo></msup><msub><mi>ν</mi><mo>ℓ</mo></msub><mo stretchy="false">)</mo><mo>=</mo><mo stretchy="false">(</mo><mn>1.1</mn><mo>±</mo><mn>0.1</mn><mo stretchy="false">)</mo><mo>%</mo></math>, with <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mo>ℓ</mo><mo>+</mo></msup><mo>=</mo><mo stretchy="false">(</mo><msup><mi>e</mi><mo>+</mo></msup><mo>,</mo><msup><mi>μ</mi><mo>+</mo></msup><mo stretchy="false">)</mo></math>. These ratios provide normalization-independent tests and may help clarify the origin of the present tension.</p>

China

Chao-Qiang Geng

Chia-Wei Liu

Sheng-Lin Liu

Puzzles in charmed baryon semileptonic decays with <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>S</mi><mi>U</mi><mo stretchy="false">(</mo><mn>3</mn><msub><mo stretchy="false">)</mo><mi>F</mi></msub></math> flavor symmetry and lattice inputs

We investigate thick-brane configurations in five-dimensional $$f(T,T_G)$$ modified teleparallel gravity. In five dimensions, the torsional Gauss–Bonnet invariant $$T_G$$ contributes dynamically, leading to genuinely new effects even at linear order. Within a warped geometry supported by a scalar field, we construct explicit solutions and show that the $$T_G$$ sector significantly modifies the brane structure. In particular, the coupling parameter controls the deformation of the warp factor and energy density; for sufficiently negative values it can induce a genuine two-peak internal structure. We further analyze the localization of spin-1/2 fermions via a Yukawa coupling. For odd Yukawa functions the system admits a normalizable chiral zero mode, while the opposite chirality remains delocalized. The massive Kaluza–Klein spectrum is strongly affected by the torsional Gauss–Bonnet term, which modifies the effective potentials and leads to the appearance of resonant quasi-localized states. Our results show that $$f(T,T_G)$$ gravity provides a richer framework for braneworld models, where torsional higher-order corrections play a key role in shaping both geometry and field localization.

Brazil

A. Moreira

F. Belchior

Mexico

Shi-Hai Dong

Greece

Chile

E. Saridakis

Thick branes and fermion localization in five-dimensional $$f(T,T_G)$$ gravity

We present a rigorous theoretical and observational analysis of the Hybrid <italic>f</italic>( <italic>Q</italic>) class of models by including the late-time modifying 1/ <italic>Q</italic> term. After deriving strict viability conditions from the analytical expansion history, we show that preserving early-universe structure formation dictates that the linear coupling be exactly unity. This fixes the background of the Hybrid model into a geometric degeneracy with &#923;CDM which is confirmed explicitly through MCMC analysis with the latest background-only probes. The physical novelty of this model is manifest in the perturbation sector, where the geometric coupling breaks the background degeneracy and induces a late-time suppression of the effective gravitational constant <italic>G<inf>eff</inf></italic>&#8239;&lt;&#8239; <italic>G<inf>N</inf></italic>. Consequently, the inclusion of RSD data reveals an amplitude compensation mechanism, by which the matching of the signature <italic>f&#963;</italic> <inf>8</inf> of the data causes the clustering amplitude <italic>&#963;</italic> <inf>8</inf> to inflate under weaker gravity. Statistical model comparison through AIC/DIC demonstrates that incorporating growth data yields a moderate to weak preference for the Hybrid model keeping the background cosmology intact. This provides a physically bounded alternative to &#923;CDM with a falsifiable signature in the large scale structure, directly testable by the next generation of galaxy surveys.

India

Ameya Kolhatkar

P.K. Sahoo

Beyond the cosmological constant: Breaking the geometric degeneracy of <italic>f</italic>( <italic>Q</italic>) cosmology via redshift-space distortions

Egypt

Tahia Dabash

United States

Moataz Emam

Germany

Lukas Schöppner

Reply to “Comment on: Symmetry and conserved quantities in $\textit{f}$($\textit{R}$)-gravity: Mei vs. Noether approaches”

In this work, two analytical solutions are proposed to characterize compact star configurations containing an effective negative-pressure fluid in the <italic>f</italic>( <italic>R, T</italic>) gravity paradigm that admit spherically symmetric geometry. We derive a system of modified field equations by taking into account a static interior spacetime, which consists of both negative-pressure fluid and ordinary matter sources. In order to investigate the interactions between the fluid components, we solve the field equations using two different equations of state. As the gravitational equations still contain more unknowns, we further use the Finch-Skea and Tolman IV spacetimes which lead us to two distinct models. The junction conditions are also applied to compute the constants associated with these solutions. Afterwards, our developed models&#8217; feasibility is explored by contrasting them with the observed characteristics of two particular stars, SAX J1808.4&#8211;3658 and Her X-1. Under certain parametric values, our results demonstrate that both the developed fluid configurations are physically realistic in this minimally coupled gravity framework.

Azerbaijan

Pakistan

M. Sharif

Tayyab Naseer

Aqsa Bashir

Examining the behavior of exotic compact stars within the <italic>f</italic>( <italic>R, T</italic>) gravity under Finch-Skea and Tolman IV spacetimes

An anisotropic Bianchi type-I cosmological model is examined in the framework of modified teleparallel gravity described by a general function $\textit{f}$($\textit{T}$, $\textit{B}$) of the torsion scalar and the boundary term. We consider the general cosmological solutions of the field equations obtained without imposing symmetry conditions at the level of the action. These solutions are employed to analyze the associated Noether symmetries and the structure of the corresponding symmetry algebras. In particular, we identify distinct classes of solutions admitting higher-dimensional Noether vector fields, whose dimensionality reflects enhanced geometrical invariance and leads to qualitatively different anisotropic cosmological behaviors. For representative cases, we investigate the geometrical evolution of the scale factors, relevant cosmological parameters, and the behavior of the effective energy density and anisotropic pressures. Our analysis shows that physically acceptable cosmological evolution arises only for restricted classes of solutions, thereby providing viability constraints on anisotropic dynamics in $\textit{f}$($\textit{T}$, $\textit{B}$) gravity.

Arshad Ali

Fiaz Hussain

General anisotropic cosmological solutions and physical viability in $\textit{f}$($\textit{T}$, $\textit{B}$) gravity

We investigate Big Bang Nucleosynthesis (BBN) in the framework of $$f(T,L_m)$$ gravity, where the gravitational Lagrangian depends on the torsion scalar $\textit{T}$ and the matter Lagrangian $$L_m$$ . Working within a semi-analytical BBN strategy, we encode departures from GR through the expansion-rate ratio $$Z\equiv H/H_{\textrm{GR}}$$ evaluated at a characteristic freeze-out temperature and combine this with the freeze-out condition and the observationally inferred abundances of deuterium and helium-4 to constrain the free parameters of three representative EFT-motivated $$f(T,L_m)$$ models. A distinctive aspect of $$f(T,L_m)$$ cosmology is that the explicit $$L_m$$ dependence can induce an effective energy exchange between the standard component and the modified-gravity sector; we therefore derive the corresponding interaction term $\textit{Q}$ and restrict our analysis to the adiabatic regime $$\varepsilon \equiv |Q_{\textrm{rad}}/(4H\rho )|\ll 1$$ throughout the BBN window, ensuring internal consistency of the temperature-based BBN mapping. Finally, to connect the radiation-era constraints with the late-time background, we present a two-fluid (dust+radiation) analysis showing how the $$L_m$$ -dependent corrections decouple as $$\ell \propto (1+z)^4\rightarrow 0$$ , yielding torsion-only ($\textit{f}$($\textit{T}$) or TEGR) cosmologies at late times on the GR-connected branch. Our results provide transparent first-pass BBN bounds on torsion–matter EFT corrections and identify viable parameter regions consistent with early-Universe data providing a controlled starting point for further early-Universe phenomenology in $$f(T,L_m)$$ gravity.

Portugal

Daniel Cruz

David Pereira

Francisco Lobo

José Mimoso

Big bang nucleosynthesis constraints on $$f(T,L_m)$$ gravity

Using the $$C-$$ metric in the context of $\textit{F}$($\textit{R}$) gravity coupled with the ModMax nonlinear electromagnetic field (the $$F(R)-$$ ModMax theory), we derive an exact black hole solution in a four-dimensional spacetime. We then examine how various parameters influence the behavior of accelerating ModMax black holes. Treating this black hole as a thermodynamic system, we calculate the Hawking temperature and entropy for the accelerating ModMax black holes within the framework of $\textit{F}$($\textit{R}$) gravity. Subsequently, we explore the impact of the parameters in $$F(R)-$$ ModMax theory on the Hawking temperature and entropy. We also assess local stability by analyzing the heat capacity. Additionally, we investigate both the angular shadow and the shadow radius of an accelerating black hole in the context of $$F(R)-$$ ModMax gravity.

Iran

B. Panah

N. Heidari

Czechia

Á. Rincón

Accelerating electrically charged ModMax black hole solutions in $\textit{F}$($\textit{R}$) gravity

The longitudinal single-target spin asymmetry in exclusive $$\pi ^0$$ production in $\textit{ep}$ collisions is a sensitive probe of the imaginary part of the gluon generalized transverse momentum dependent distribution $$F_{1,4}^g$$ . It appears as a characteristic $$\sin (2\phi )$$ azimuthal correlation between the transverse momenta of the scattered electron and the recoil proton, generated by Coulomb–nuclear interference; consequently, the Primakoff process should be included. We compute the relevant gluon distributions in a light-front spectator model of the proton that explicitly incorporates gluonic degrees of freedom. This work presents the first model calculation of the imaginary part of $$F_{1,4}^g$$ and delivers predictions for the resulting asymmetries in kinematics relevant to the planned Electron–Ion Colliders (EIC and EicC), providing theoretical predictions for upcoming measurements.

Chentao Tan

Zhun Lu

Accessing gluon GTMD $$F^g_{1,4}$$ via the $$\langle \sin (2\phi )\rangle $$ azimuthal asymmetry of exclusive $$\pi ^0$$ production in $\textit{ep}$ collisions