Heavy quark (HQ) momentum ( <italic>&#954;</italic>) and spatial diffusion ( <italic>D<inf>s</inf></italic>) coefficients are computed in a non-perturbative thermal QCD medium in the presence of a background magnetic field of arbitrary strength. Both perturbative and non-perturbative effects are incorporated via the in-medium HQ potential, obtained from the resummed gluon propagator. We find that the momentum diffusion coefficients become anisotropic even in the static heavy quark limit, with the magnetic field direction defining the axis of anisotropy. This anisotropy originates from restrictions on longitudinal momentum diffusion in the gluon spectral function, and naturally leads to two spatial diffusion coefficients ( <math altimg='si1.svg'><msubsup><mi>D</mi><mi>s</mi><mi>L</mi></msubsup></math>, <math altimg='si2.svg'><msubsup><mi>D</mi><mi>s</mi><mi>T</mi></msubsup></math>). Non-perturbative effects are found to be dominant at low temperatures. These results provide a more consistent input for Langevin based calculations of the heavy quark directed flow at RHIC and LHC energies.

China

Debarshi Dey

Poland

Romania

Aritra Bandyopadhyay

Yifeng Sun

India

Santosh K. Das

Non-perturbative heavy quark diffusion coefficients in arbitrarily magnetized quark-gluon plasma

The findings on the spin polarization of Λ, Ξ, and Ω hyperons and spin alignment of <italic>K</italic> &#8270;0, <italic>&#981;</italic>, and <math altimg='si8.svg'><msup><mi>D</mi><mrow><mo>*</mo><mo>+</mo></mrow></msup></math> mesons in relativistic heavy-ion collision experiments at the RHIC and LHC facilities propose the emergence of a strong vorticity field produced in these collisions. Contemplating the potential impact of vorticity on the space-time evolution of deconfined QCD matter and its freeze-out properties, we aim to investigate its characteristics within the medium. We introduce a complementary and data-driven approach to quantify the global vorticity field by extracting it directly from the transverse momentum spectra of produced hadrons. Employing the experimental data for &#923;, &#926;, &#937;, <italic>K</italic> &#8270;0, <italic>K</italic> *&#8239;&#177;&#8239;, <italic>&#981;, &#961;</italic>, and <math altimg='si8.svg'><msup><mi>D</mi><mrow><mo>*</mo><mo>+</mo></mrow></msup></math> at mid-rapidity in Au+Au and Pb+Pb collisions over a wide range of beam energies, <math altimg='si9.svg'><mrow><msqrt><msub><mi>s</mi><mrow><mrow><mi mathvariant='normal'>N</mi></mrow><mi>N</mi></mrow></msub></msqrt><mo linebreak='goodbreak'>=</mo><mn>7.7</mn></mrow></math> GeV-5.02 TeV, and centrality classes, we systematically examine spin-vorticity coupling in the medium. Our finding on the magnitude of the extracted vorticity is consistent with values deduced from &#923; and <math altimg='si1.svg'><mover accent='true'><mstyle mathvariant='normal'><mi>&#923;</mi></mstyle><mo>&#175;</mo></mover></math> polarization measurements using statistical thermal models under the non-relativistic limit. Notably, we observe a prominent particle-species dependence of the vorticity, as well as a non-trivial variation with collision centrality and beam energy. These results indicate that vorticity-driven spin phenomena are sensitive to hadron structure and freeze-out dynamics, providing new constraints on the rotational properties of the QCD matter.

Bhagyarathi Sahoo

Captain R. Singh

Raghunath Sahoo

Probing rotational dynamics of quark gluon plasma via global vorticity

We propose that simple neural networks (NNs) trained on crossing symmetry can reconstruct conformal correlators restricted to a line to remarkable accuracy. The input is minimal: an external scaling dimension, a spectral gap, and the value of the correlator at a single point. We present evidence across a wide range of conformal theories and dimensions, for both four-point and thermal two-point functions. We attribute these observations to the <italic>spectral bias</italic> of gradient-based NN training, which appears to align with an intrinsic smoothness property of conformal field theory. This suggests a novel variational principle for conformal correlators and opens a path towards a powerful new computational framework for non-perturbative quantum field theory.

United Kingdom

Kausik Ghosh

Sidhaarth Kumar

Greece

Vasilis Niarchos

Andreas Stergiou

Neural networks reveal a universal bias in conformal correlators

A recently developed topological approach offers novel insights into photon spheres, which are fundamental to the formation of black hole shadows. In this study, we extend this topological analysis to higher-dimensional, static, spherically symmetric, and asymptotically flat black holes. By examining the asymptotic properties of the vector field associated with the photon spheres, we demonstrate that their topological charge is consistently −1. This result is a dimensionally independent invariant, guaranteeing the existence of at least one standard (unstable) photon sphere outside the event horizon. We further explore this conclusion by analyzing two distinct regular black hole solutions derived from pure gravity theory, confirming that the topological charge remains −1 irrespective of the spacetime dimension. These results provide a robust and universal characterization of photon spheres in higher-dimensional spacetimes.

Jun-Lei Chen

Shan-Ping Wu

Shao-Wen Wei

The universal topological charge of black hole photon spheres in higher dimensions

We examine the <italic>q</italic> 2-binned distributions of the <italic>D</italic>&#8239;&#8594;&#8239; <italic>K&#956;&#957;</italic> decay rate and of the corresponding forward-backward asymmetry which were recently measured by BESIII, showing a mild deviation from the Standard Model predictions. We point out that the proposed solution to remedy the discrepancy by turning on a complex-valued New Physics coupling is in tension with the constraints deduced from the LHC bounds on the high- <italic>p<inf>T</inf></italic> tail of the relevant Drell-Yan process. We then show that there are several plausible scenarios that are compatible with both the measured low-energy and high-energy constraints but the selected couplings appear to be too small to be observed in the measurements of integrated observables, except for possibly the <italic>q</italic> 2-binned distribution of the angular observables relevant to <italic>D<inf>s</inf></italic>&#8239;&#8594;&#8239; <italic>&#981;</italic>(&#8239;&#8594;&#8239; <italic>KK</italic>) <italic>&#956;&#957;</italic> or &#923; <inf><italic>c</italic></inf>&#8239;&#8594;&#8239;&#923;(&#8239;&#8594;&#8239; <italic>p&#960;</italic>) <italic>&#956;&#957;</italic> modes.

France

Switzerland

D. Bečirević

Brazil

M. Martines

S. Rosauro-Alcaraz

O. Sumensari

Interpreting the results on exclusive <italic>c</italic>&#8239;&#8594;&#8239; <italic>s&#956;&#957;</italic> modes

This letter presents an assessment of quantum gravity effects on extreme-mass-ratio inspirals (EMRIs) for the rotating quantum Oppenheimer-Snyder (qOS) black hole. Employing the adiabatic evolution, we compute the gravitational wave (GW) dephasing, which quantifies the cumulative phase shift induced by the quantum correction <italic>&#945;</italic>. We further generate the augmented analytic kludge (AAK) waveform and investigate the faithfulness between the waveforms with and without the quantum parameter <italic>&#945;</italic> for different values of <italic>a</italic>. Our results reveal that the quantum gravity effect induces detectable imprints in LISA, while the presence of rotation suppresses these signatures. We further show that the opposite influences of <italic>&#945;</italic> and <italic>a</italic> can compensate in the accumulated dephasing, pointing to a potential degeneracy between rotation and quantum corrections. This suggests that rotational degrees of freedom must be carefully accounted for when probing quantum gravity with EMRI observations.

Dan Zhang

Shulan Li

Guoyang Fu

Jian-Pin Wu

Assessing EMRI detectability of the rotating quantum Oppenheimer-Snyder black hole

Hao-Fu Zhu

Guo-Zhu Liu

Xufen Wu

Corrigendum to “Rapid cooling of the Cassiopeia A neutron star due to superfluid quantum criticality” [Physics Letters B 879 (2026) 140591]

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.

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

In this paper, we examine the dynamics of test particles in the Kerr-Sen black hole (BH) spacetime and its properties. In this case, the study concentrates on equatorial circular orbits and their stability properties using the effective potential formalism approach. We derive conditions for stable circular motion and examine the influence of BH parameters on the observed dynamics properties of the orbital structure. Furthermore, we investigate small harmonic perturbations around circular orbits and calculate the associated oscillation frequencies measured by distant asymptotic observers. In this context, these frequencies provide a direct probe of the underlying geometry and deviation from the Kerr limit. We also perform a numerical analysis to illustrate the dependence of orbital stability and oscillatory behavior on the rotation and charge parameters of the Kerr–Sen solution. In addition, our general relativistic hydrodynamical simulations of two-dimensional equatorial planar accretion show that increasing the Kerr–Sen spacetime parameter <italic>q</italic> enhances the mass-accretion rate and modifies the local density and radial-velocity profiles near the black hole, with the strongest deviation from the Kerr case appearing for the largest value of <italic>q</italic>.

Shahid Hussain Gurmani

Kuwait

Orhan Donmez

Algeria

Abdelmalek Bouzenada

Imtiaz Khan

Azerbaijan

G. Mustafa

Equatorial circular orbits, epicyclic frequencies, and planar accretion in Kerr–Sen black hole spacetimes

We investigate the orbital and oscillatory dynamics of test particles in the gravitational field of an Euler–Heisenberg black hole surrounded by perfect-fluid dark matter. We derive analytical expressions for the radial dependence of the specific energy and specific angular momentum associated with stable equatorial circular orbits. Using the effective potential approach, we analyze the stability conditions of these orbits and explore the properties of the innermost stable circular orbits. We numerically integrate the equations of motion for test particles, construct trajectories around a non-rotating Euler–Heisenberg black hole embedded in perfect-fluid dark matter, and examine a variety of dynamical configurations. In addition, we study the effective force acting on the particles. We compute the radial and vertical epicyclic frequencies as functions of the model parameters and characterize the main features of the quasi-periodic oscillations of test particles on stable circular orbits in the equatorial plane of the black hole.

Oman

S.K. Maurya

Pakistan

Allah Ditta

Saudi Arabia

Akram Ali

Uzbekistan

Alisher Abduvokhidov

Farruh Atamurotov

Influence of dark matter on epicyclic frequencies and orbital stability in the vicinity of Euler–Heisenberg black holes: Observational prospects in strong gravity