Pulsars are observed to emit bright and spatially extended gamma-ray emission at multi-TeV energies. These so-called “TeV halos” are now understood to be a nearly universal feature of middle-aged pulsars. However, many of the key physical processes that govern these systems, particularly those affecting particle diffusion, remain poorly constrained. We aim to evaluate the ability of the Cherenkov Telescope Array (CTA) to probe the physical properties of TeV halos, with a focus on the nearby and well-studied case of the Geminga pulsar. We simulate gamma-ray emission from various TeV halo models, incorporating different assumptions for the injected electron spectrum, spin-down evolution, and energy-dependent diffusion. These models are then used to forecast CTA’s sensitivity to spectral and spatial differences, based on realistic mock observations and instrument response simulations. We find that CTA will be able to distinguish between a wide range of TeV halo models that are currently consistent with existing data. In particular, CTA observations can constrain the normalization, energy dependence, and spatial extent of the diffusion coefficient surrounding Geminga, as well as the spectral shape of the injected electron population.

United States

D. Hooper

E. Pinetti

A. Sokolenko

Unraveling TeV halos with the Cherenkov Telescope Array

Scientific AI is rapidly transforming fundamental physics research and challenging defining aspects of the fundamental physics methodology. We discuss opportunities and dangers of this transformation and find exciting benefits from a close interaction between AI and fundamental physics, provided that we remain aware of the scientific methodologies of the respective fields. For fundamental physics, we discuss two such aspects: statistical validation and a generalizing theory description, both with the goal of discovering new physics in vast datasets.

Germany

Michael Krämer

Tilman Plehn

Machine learning is good for physics—and vice versa

Anomalies in the non-leptonic $$\bar{B}^0\rightarrow D^{(*)+}K^{(*)-}$$ and $$\bar{B}^0_s\rightarrow D^{(*)+}_s\pi ^-$$ decays may be an indication of physics beyond the Standard Model, but the large deviations require strongly coupled new physics that should be visible at colliders. We explore three new directions that could lead to viable new physics models, performing a detailed collider study to examine the possible weakening of previously known constraints on additional $$SU(2)_L$$ doublets. Our results show that, despite the difficulty of probing $$t\bar{t}$$ final states, increasing the branching ratio to this decay mode does not significantly weaken the bounds on weak doublet scalars, as additionally existing charged Higgs searches are equally strong. Beyond this, we analyse a potentially large breakdown of QCD factorisation by including large-power corrections to $\textit{B}$ decays, and the effect of diluting collider searches with multi-scalar extensions. We find that these typical model-building routes for constructing a viable scenario remain constrained by collider measurements, indicating that these non-leptonic anomalies remain among the most puzzling discrepancies from the SM.

United Kingdom

Jack Araz

Christoph Englert

Matthew Kirk

Gilberto Tetlalmatzi-Xolocotzi

New insights into the $$b\rightarrow c \bar{u}q$$ puzzle through Top–Bottom synergies

Over the last decade, non-relativistic theories have attracted considerable attention. In general, such theories can be obtained by contracting relativistic parent theories. In this work, we discuss features of non-relativistic supersymmetric field theories from both the Galilean and Carrollian points of view that may be useful for constructing electric and magnetic non-relativistic theories.

Türkiye

Osman Ergec

Aspects of non-relativistic supersymmetric theories

We constrain three holographic-inspired dark energy models, namely holographic dark energy (HDE), agegraphic dark energy (ADE), and Ricci dark energy (RDE), using late-time observations from cosmic chronometers, Type Ia supernovae (SNe Ia), DESI DR2 baryon acoustic oscillations (BAO), and redshift-space distortion (RSD) growth measurements. Five data combinations are considered: $$H(z)+$$ Pantheon+, $$H(z)+$$ DESI DR2+Pantheon+, $$H(z)+$$ DESI DR2+DES-Dovekie, $$H(z)+$$ DESI DR2+DESY5, and $$H(z)+$$ DESI DR2+DES-Dovekie+RSD. We perform Bayesian Markov chain Monte Carlo parameter estimation and compare the models with AIC and BIC. In the BAO-included combinations, HDE gives $$H_0\simeq 67.3$$ – $$68.0~\mathrm {~km~s^{-1}~Mpc^{-1}}$$ , $$\Omega _{m0}\simeq 0.270$$ –0.272, and $$c\simeq 1$$ , indicating an expansion history close to the de Sitter boundary rather than a robust phantom regime. ADE yields a stable agegraphic parameter $$n\simeq 2.78$$ –2.81, while RDE gives $$\gamma \simeq 0.53$$ –0.55 and persistently favors a low matter density, $$\Omega _{m0}\simeq 0.215$$ –0.219. Treating $$r_d$$ as a free parameter reveals a strong negative correlation between $$H_0$$ and $$r_d$$ , and the RSD-included combination provides a growth-level consistency check through $$f\sigma _8(z)$$ without constituting a full perturbative stability analysis. None of the three models significantly alleviates the Hubble tension. Overall, HDE shows the most balanced phenomenological behavior among the three models, although current late-time data do not decisively prefer it over $$\Lambda \text {CDM}$$ .

China

Jiayuan Huang

Tonghua Liu

Chenggang Shao

Late-time cosmological constraints on three holographic dark energy models with DESI DR2 BAO and Type Ia supernovae

We investigate the radial motion and tidal forces experienced by neutral test particles in multi-horizon black hole solutions arising from Einstein gravity coupled to nonlinear electrodynamics (NED). Focusing on the three- and four-horizon configurations, we examine how nonlinear electromagnetic corrections modify the causal structure, radial geodesic motion, and tidal-force profiles in comparison with the Schwarzschild and Reissner–Nordström (R–N) spacetimes. Our analysis shows that the NED field gives rise to multiple zero crossings in both the radial and angular tidal-force components, leading to successive transitions between stretching and compressive tidal regimes. More importantly, the radial equation of motion contains classically forbidden regions bounded by bounce-back points. For the class of trajectories considered in this work, these forbidden regions prevent particles from entering the spacetime domain where the tidal forces become divergent. In the super-extremal regime admitted by these solutions, the forbidden region may extend beyond the event horizon, preventing particles released from rest at sufficiently large distances from crossing the horizon. We further identify a systematic ordering of the critical charge values associated with the appearance of tidal-force zero crossings, additional horizons, and bounce-back points. For both the three- and four-horizon configurations, these critical values satisfy a hierarchical ordering, indicating that changes in the tidal-force structure precede the corresponding modifications of the horizon configuration. These results demonstrate that nonlinear electrodynamics can substantially modify the classical dynamics of neutral particles in multi-horizon black hole spacetimes through the combined effects of forbidden regions, multiple tidal transitions, and changes in the horizon structure.

Iran

Mohammad Afshar

J. Sadeghi

Beyond the bounce: multiple tidal sign reversals and turning-point bifurcations in multi-horizon black holes

We present a method to measure electric-charge transport in high-energy nuclear collisions using a beam-energy scan of isobaric systems. Comparing collisions of nuclei with identical mass number but different atomic numbers allows the charge difference ( $$\varDelta Q$$ ) to be extracted with a double-ratio technique that suppresses most experimental systematic uncertainties. By varying the beam energy, the rapidity gap ( $$\varDelta y$$ ) over which electric charge is transported can be systematically scanned. Simulations of Ru+Ru and Zr+Zr collisions at $$\sqrt{s_{\textrm{NN}}}=19.6$$ –200 GeV with UrQMD and 8 Angantyr show that midrapidity $$\varDelta Q$$ decreases exponentially with increasing $$\varDelta y$$ , with the slope parameter exhibiting strong model dependence. Comparisons to baryon-number transport reveal distinct patterns. In both UrQMD and 8 Angantyr (with and without final-state baryon junctions), where baryon number is carried solely by valence quarks, the rapidity slope for baryon transport is larger than that for electric-charge transport. In contrast, scenarios that include baryon junctions in the initial state are expected to produce the opposite trend. This demonstrates that an isobar beam-energy scan provides a sensitive probe of electric-charge transport and offers new constraints on the microscopic mechanisms governing conserved-charge redistribution in QCD matter.

Wendi Lv

Niseem Magdy

Rongrong Ma

Zebo Tang

Prithwish Tribedy

Chun Tsang

Zhangbu Xu

Measuring charge transport in high-energy nuclear collisions with an energy scan of isobaric collisions

In the present work, we propose to investigate the productions of $$P_{c}(4312)$$ , $$P_{c}(4440)$$ , and $$P_{c}(4457)$$ in the $$e^{+} e^{-} \rightarrow p \bar{p} J/\psi $$ process by utilizing an effective Lagrangian approach, where $$P_{c}(4312)$$ is considered as $$\Sigma _{c} \bar{D}$$ molecular state with $$J^{P}=1/2^{-}$$ , while $$P_{c}(4440)$$ and $$P_{c}(4457)$$ are considered as $$\Sigma _{c} \bar{D}^{*}$$ molecular states with $$J^{P}=1/2^{-}$$ and $$J^{P}=3/2^{-}$$ , respectively. For the $$e^{+} e^{-} \rightarrow \bar{p} P_{c}(4312)$$ , $$e^{+} e^{-} \rightarrow \bar{p} P_{c}(4440)$$ , and $$e^{+} e^{-} \rightarrow \bar{p} P_{c}(4457)$$ processes, the cross sections are evaluated to be ( $$27.8^{+42.2}_{-17.9}$$ ) fb, ( $$38.7^{+58.6}_{-25.1}$$ ) fb, and ( $$1.44^{+2.18}_{-0.93}$$ ) fb at $$\sqrt{s}=6$$ GeV, respectively, where the central values are estimated with $$\Lambda _{r}=2.5$$ GeV, and the uncertainties are resulted from the variations of $$\Lambda _{r}$$ from 2.0 to 3.0 GeV. Considering that the $$P_{c}$$ states can decay into $$J/\psi p$$ , we estimate the cross sections for $$e^{+} e^{-} \rightarrow p \bar{p} J/\psi $$ and the differential cross sections depending on the $$J/\psi p$$ invariant mass. At $$\sqrt{s}=6$$ GeV, the cross sections for $$e^{+} e^{-} \rightarrow p \bar{p} J/\psi $$ are estimated to be ( $$14.7^{+22.2}_{-9.50}$$ ) fb. Moreover, our estimations indicate that the cross section resulted from the $$P_{c}(4440)$$ and $$\bar{P}_{c}(4440)$$ intermediate states is dominant. In the $$J/\psi p$$ invariant mass spectrum, our estimations reveal that the peak structure between 4.42 and 4.46 GeV primarily originates from $$P_{c}(4440)$$ .

Quan-Yun Guo

Dian-Yong Chen

$$P_{c}(4312)$$ , $$P_{c}(4440)$$ , and $$P_{c}(4457)$$ productions in $$e^{+} e^{-}$$ collisions

We investigate the light curve of an isolated bright spot in a Keplerian orbit around a Kerr black hole candidate to probe possible deviations from the standard event-horizon picture. In particular, we explore the presence of a reflective surface, namely a “mirror” near the horizon, and its observable consequences. We present estimates on the time delays of the echoes of electromagnetic radiation from the mirror or some other reflecting area related to black hole mimickers. Our results show that photon reflections from such a surface imprint distinct late-time features in the light curve, producing an electromagnetic analogue of gravitational wave echoes. For lower values of the spin, the reflected signal appears within the same orbital period and leads to a noticeable enhancement of the flux. In contrast, for higher spins, the effect emerges only after several orbits, giving rise to a characteristic echo-wave train. These features provide a potential observational signature of horizon-scale modifications in compact objects.

Czechia

Sudipta Hensh

Jan Schee

Zdeněk Stuchlík

Timing of echoes in electromagnetic radiation from hot spots orbiting a Kerr black hole impostor

We investigate the thermodynamic behaviour of an AdS black hole arising from nonlinear electrodynamics-corrected gravity, incorporating quantum effects through thermal fluctuations. From the Einstein–Euler–Heisenberg framework, we consider the modified black hole solution and analyse its thermodynamic properties in the extended phase space. Logarithmic and inverse-area corrections to the entropy are obtained, leading to modified expressions for enthalpy, internal energy, Helmholtz free energy and Gibbs free energy. The corrected specific heat exhibits multiple divergences and sign changes, signalling genuine second-order phase transitions and revealing a quantum-stabilized microscopic phase followed by universal macroscopic instability. Our results demonstrate that thermal fluctuations qualitatively restructure the thermodynamic phase space and highlight the dominant role of quantum corrections in governing the black hole stability.

India

Siddhartha Borah

Azerbaijan

Dhruba Gogoi

Kalyan Bhuyan

Quantum-corrected thermodynamics and phase structure of AdS Euler–Heisenberg black hole