Kaniadakis holographic dark energy is a one-parameter extension of the standard HDE framework, in which the horizon entropy is reformulated using Kaniadakis entropy. At the cosmological level, it has been shown to give rise to modified Friedmann equations, leading to a richer phenomenology compared to $$\Lambda $$ CDM. In this work we test the Kanadiakis holography model against multiple late-time observational probes, including Type Ia supernovae from PantheonPlus and Union3, Cosmic Chronometer measurements of the Hubble parameter and Baryon Acoustic Oscillation from the Dark Energy Spectroscopic Instrument Data Release 2 (DESI DR2). Using a Bayesian inference approach with MCMC methods, we constrain the cosmological parameters of the model and evaluate its performance against $$\Lambda $$ CDM through the Akaike Information Criterion. We find that Kaniadakis holography can provide a better fit for some data combinations, although $$\Lambda $$ CDM remains slightly statistically favored overall. These results highlight Kaniadakis holography as a competitive alternative to the standard cosmological model, offering valuable insights into the role of generalized entropy in dark energy dynamics.

Spain

Giuseppe Luciano

South Africa

Chile

Andronikos Paliathanasis

Late-time cosmological constraints on Kaniadakis holographic dark energy

In the present study, we investigate the quasibound states and scalar cloud of relativistic charged scalar fields bound to a Kerr–Newman black hole. We present the exact eigensolutions of the governing Klein–Gordon equation with non-minimal coupling in the black hole background. By imposing boundary conditions on the quasibound states, we are able to find the exact complex quasibound state frequencies of the corresponding radial wave functions in terms of the confluent Heun polynomial. The quantization formula obtained here allows us to determine the exact resonance frequency of a charged scalar cloud, thereby revisiting and extending the earlier result derived through the asymptotic matching approach. Our analysis shows that a stationary configuration can exist only when the charge coupling satisfies $$qr_Q<0$$ . In this case, the scalar cloud remains stationary due to a flux balance: an outgoing flux from the Cauchy horizon compensates for the ingoing particle flux at the event horizon. This mechanism distinguishes scalar clouds from ordinary quasibound states, where such a compensating flux is absent.

Thailand

David Senjaya

Revisiting Kerr–Newman black hole’s charged scalar cloud: flux balance

In this article, the electroweak transition form factors of $$\Lambda _b\rightarrow \Lambda _c$$ and $$\Xi _b\rightarrow \Xi _c$$ are analyzed within the framework of three-point QCD sum rules. In phenomenological side, all possible couplings of interpolating current to hadronic states are considered. In QCD side, the perturbative part and the contributions of vacuum condensates up to dimension 8 are also included. With the estimated form factors, we study the decay widths and branching ratios of semileptonic decays $$\Lambda _b\rightarrow \Lambda _cl\bar{\nu }_l$$ and $$\Xi _b\rightarrow \Xi _cl\bar{\nu }_l$$ ( $$l=e,\mu $$ and $$\tau $$ ). Our results for the branching ratios of $$\Lambda _b\rightarrow \Lambda _cl\bar{\nu }_l$$ are comparable with experimental data and the results from other collaborations. In addition, our prediction for the branching ratio of $$\Xi _b\rightarrow \Xi _cl\bar{\nu }_l$$ can provide a valuable reference for future experimental measurements.

China

Jie Lu

Guo-Liang Yu

Dian-Yong Chen

Zhi-Gang Wang

Bin Wu

Analysis of the semileptonic decays $$\Lambda _b\rightarrow \Lambda _cl\bar{\nu }_l$$ and $$\Xi _b\rightarrow \Xi _cl\bar{\nu }_l$$ in QCD sum rules

This work presents a piecewise deterministic Markov process model for describing performance deterioration in resistive plate chambers (RPC) under uniform background irradiation. The approach accommodates high irradiation rates and arbitrary charge spectra. When applied to the one-dimensional single-cell model of a three-layer single-gap RPC, it shows agreement with state-of-the-art Monte Carlo simulations, which has not been achieved so far. The Markov process model is further applied to the single-cell model with polarizable resistive layers and the two-dimensional counterpart. Moreover, we show that incorporating streamer-like charge events allows the model to reproduce experimental data on efficiency curves under irradiation. These large charge events explain the experimentally observed reduction of the efficiency plateau at high irradiation rates. Extending this insight to eco-friendly gas mixtures reveals that suppressing streamers in general is crucial for achieving high-rate capability.

Switzerland

Dario Stocco

Michele Pulver

Christian Franck

Markov modeling of performance deterioration in irradiated resistive plate chambers

We analyze the generalizations of Kaluza–Klein compactifications of 5D Horndeski theory. They are Scalar–Vector–Tensor (SVT) theories with higher derivatives in the action, but with second order equations of motion. The vector field is invariant under a U(1) gauge transformation and the Scalar–Tensor sector corresponds to Horndeski theory. A subclass of these SVT theories is such that the Horndeski functions $$G_4(\pi ,X)$$ and $$G_5(\pi )$$ remain free, while the speed of the tensor and vector modes is exactly the same. We show a subclass where the vector sector retains freedom through new functions of $$\pi ,\, X$$ while the speed of the vector modes still tracks the speed of the tensor modes.

Russia

S. Mironov

A. Shtennikova

M. Valencia-Villegas

Ghost-free, gauge invariant SVT generalizations of Horndeski theory

In a recent article, Hod (Eur Phys J C 80:982, 2020) has concluded the non-existence, heretofore unnoticed, of a unified Thorne’s hoop conjecture that holds for the quasi-local mass, $$\mathcal {M}(r\le R_{+})$$ for static Reissner–Nordstrőm black hole, but does not hold for the spinning electrically charged Kerr–Newman black holes, when the same quasi-local mass is used. While the conclusion is correct and important, we wish to point out a curious exception for which the conjecture holds in a unified way for both the static and spinning $\textit{tidal}$ charged 4$\textit{d}$ braneworld black holes of string theory, when the mass in the conjecture is the same quasi-local mass.

India

Amrita Bhattacharya

Ramil Izmailov

Ramis Karimov

Comments on the non-existence of unified hoop conjecture

We have revisited quasi-exponential model of inflation in the light of recent ACT-DR6 and Planck data along with latest constraint on the amplitude of primordial gravitational waves. For our analysis we have followed Mukhanov approach for inflationary equation-of-state employing Hamilton–Jacobi formulation. We find that the model is capable of mimicking latest Planck results by providing excellent fit to scalar spectral index and its running. Not only that, amount of primordial gravitational waves is also within the present observational bound, $$r<0.032$$ . In addition to that, when the combination of ACT-DR6 and Planck joint with BICEP/Keck 2018 data is taken into account inflationary predictions from quasi-exponential model are in excellent agreement. The model also yields sublime fit to the result of joint analysis of ACT-DR6, Planck joint with BICEP/Keck 2018 and DESI-Y1 data. The futuristic CMB missions LiteBIRD, Simons Observatory and CMB-S4 are promising to detect primordial gravitational waves if $$r\ge 0.003$$ . We have also forecasted inflationary predictions from quasi-exponential model of inflation assuming the sensitivities of LiteBIRD, Simons Observatory and CMB-S4 along with combination of LiteBIRD and CMB-S4. We found that in each case quasi-exponential inflation may render excellent fit provided $$r\ge 10^{-2}$$ . However, non-detection of primordial gravitational waves by LiteBIRD, Simons Observatory and CMB-S4 will potentially rule out quasi-exponential model.

Barun Pal

The fate of quasi-exponential inflation in the light of ACT-DR6

This study investigates the performance of bent silicon crystals intended to channel hadrons in a fixed-target experiment at the Large Hadron Collider (LHC). The phenomenon of planar channelling in bent crystals enables extremely high effective bending fields for positively charged hadrons within compact volumes. Particles trapped in the potential well of high-purity, ordered atomic lattices follow the mechanical curvature of the crystal, resulting in macroscopic deflections. Although the bend angle remains constant across different momenta (i.e., the phenomenon is non-dispersive), the channelling acceptance and efficiency still depend on the particle momentum. Crystals with lengths in the range of 5 to 10 cm, bent to angles between 5 and 15 mrad, are under consideration for measurements of the electric and magnetic dipole moments of short-lived charmed baryons, such as the $$\varLambda _c^+$$ . Such large deflection angles over short distances cannot be achieved using conventional magnets. The principle of inducing spin precession through bent crystals for magnetic dipole moment measurements was first demonstrated experimentally in the 1990s. Building on this concept, experimental layouts are now being explored for implementation at the LHC. The feasibility of such measurements depends, among other factors, on the availability of crystals that exhibit the required mechanical properties to reach the necessary channelling performance. To address this, a dedicated machine experiment – TWOCRYST – has been installed in the LHC to carry out beam tests in the TeV energy range. The bent crystals for TWOCRYST were fabricated and tested using both X-ray diffraction and high-momentum hadron beams at 180 GeV/c at the CERN Super Proton Synchrotron (SPS) extraction lines. Two crystals based on established technologies were included in this test. In addition, a crystal bent via anodic bonding was tested for the first time with high-energy hadrons to assess its potential for future accelerator applications. This paper presents an analysis of the performance of the three tested crystals and, where possible, outlines key differences in their properties attributed to the respective bending techniques.

Italy

L. Bandiera

R. Cai

S. Carsi

S. Cesare

United Kingdom

K. Dewhurst

M. D’Andrea

D. Salvador

P. Gandini

V. Guidi

P. Hermes

G. Lezzani

L. Malagutti

D. Marangotto

C. Maccani

A. Mazzolari

A. Merli

D. Mirarchi

P. Monti-Guarnieri

C. Montanari

R. Negrello

N. Neri

M. Prest

S. Redaelli

M. Romagnoni

A. Selmi

G. Tonani

E. Vallazza

Germany

D. Veres

F. Zangari

Poland

M. Zielińska

Performance of short and long bent crystals for the TWOCRYST experiment at the Large Hadron Collider

Astrophysical evidence has hinted at the existence of a nonzero NUT charge, which breaks the $$\mathbb {Z}_2$$ symmetry of spacetime and induces novel features in geodesics. In this work, we investigate the Lense–Thirring precession of the spherical orbits in the Kerr–Taub–NUT spacetime, with particular emphasis on its connection to recent observations of black hole jet precession. We analyze the reflection symmetry breaking in trajectories of the spherical orbits and extract their precession angular velocity. It is worth noting that in the absence of spin, the spherical orbits reduce to tilted circular orbits without precession, whereas for nonzero spin, the precession angular velocity increases with the absolute value of the NUT charge. We then model the motion of particles near the warp radius of a tilted accretion disk using the spherical orbits and constrain the black hole parameter space based on the observed jet precession of M87*. The results indicate that regions with low spin and large NUT charge were excluded, and that the jet precession measurements cannot distinguish the sign of the NUT charge. The excluded region is larger for retrograde accretion disks than for prograde ones. We also find that this observation do not allow a clear distinction between black holes and naked singularities. Moreover, we also explore how black hole parameters influence the structure of accretion disk. These results have important theoretical and astronomical significance for us to deeply understand NUT space-time.

Xiang-Cheng Meng

Shan-Ping Wu

Shao-Wen Wei

Precession of spherical orbits for the spacetime without $$\mathbb {Z}_2$$ symmetry induced by NUT charge

We investigate the relationship between thermodynamic phase transitions and the Lyapunov exponent of charged regular anti-de Sitter black holes in quasi-topological gravity. Our results show that the Lyapunov exponent displays multivalued behavior during phase transitions. Moreover, along the coexistence curve the Lyapunov exponent changes discontinously and continuously at the critical point. Near the critical point, the Lyapunov exponent follows a power-law behavior with a critical exponent of 1/2, suggesting its role as an order parameter and encodes information on black hole phase transitions.

Hao Xie

Si-Jiang Yang

Probing phase transitions of regular black holes in anti-de Sitter space with Lyapunov exponent