We study the new $Z'$ boson as a portal for the production of Higgs bosons $h_0$ and $H_0$ predicted by the Bestest Little Higgs Model through Higgs-strahlung processes $\mu^+\mu^- \to (Z, Z') \to Zh_0, ZH_0$ . We focus on the resonant and nonresonant effects of the $Zh_0, ZH_0$ signals. In our analysis, we consider the center-of-mass energies of $\sqrt{s}=3, 4, 6, 10, 30$ TeV and integrated luminosities of ${\cal{L}}=2, 4, 6, 10, 30$ ${ {\rm{ab}}^{-1}}$ projected for a future muon collider. The possibility of performing precision measurements for Higgs bosons $h_0$ and $H_0$ is very promising for the future muon collider. Furthermore, our results may be useful to the High Energy Physics community. Complementarily, we generate and provide the Feynman rules necessary for studying processes $\mu^+\mu^- \to (Z, Z') \to Zh_0, ZH_0$ .

J.M. Martínez-Martínez

A. Gutiérrez-Rodríguez

E. Cruz-Albaro

M.A. Hernández-Ruíz

New $\textit{Z}$' boson of the bestest little Higgs model as a portal to signatures of Higgs bosons $\textit{h}$ $_{0}$ and $\textit{H}$ $_{0}$ at the future muon collider

In this paper, we investigate the gravitational lensing properties of magnetically charged black holes within the framework of nonlinear electrodynamics. We derive the deflection angle and examine the influence of the nonlinear electrodynamics parameter $$\xi $$ on light bending. We initially employ a geometric approach based on the Gauss–Bonnet theorem to analyze the gravitational deflection of null and timelike particles. This method encapsulates the global characteristics of the lensing effect in an elegant manner. In the subsequent part of the work, we explore the impact of nonlinear electromagnetic corrections on the black hole shadow. Using numerical techniques, we study the behavior of the photon sphere and demonstrate that a reduction in the photon sphere radius leads to a correspondingly smaller shadow. We compare these results with those for the Schwarzschild and Reissner–Nordström black holes, highlighting the distinctive features introduced by nonlinear electrodynamics. Furthermore, we examine the strong deflection limit for light trajectories near these black holes, focusing on the roles of both the magnetic charge $$Q$$ and the nonlinear parameter $$\xi $$ . Our analysis reveals that the combined effects of $$Q$$ and $$\xi $$ enhance the strong deflection angle, resulting in a more pronounced lensing effect than that predicted by the classical Reissner–Nordström solution. These findings suggest that the nonlinear interactions may provide a potential observational signature for identifying NED black holes.

Pakistan

Italy

Hira Waseem

Philippines

Nikko Lobos

Türkiye

Ali Övgün

Reggie Pantig

Analyzing deflection angles and photon sphere dynamics of magnetically charged black holes in nonlinear electrodynamic

Recently, an exact black hole solution in non-minimal Einstein–Yang–Mills theory was obtained, and its quasinormal modes were subsequently analyzed using the JWKB approximation (Gogoi and Ponglertsakul in Eur. Phys. J. C 84:652, 2024. . [gr-qc]). However, we demonstrate that this analysis lacks sufficient accuracy when studying modes with $$\ell \le n$$ , where $$\ell $$ is the multipole number and $\textit{n}$ is the overtone number. To address this, we compute the quasinormal frequencies using the precise Leaver method. Our results show that while the fundamental mode deviates only slightly from the Schwarzschild value, the first few overtones exhibit significantly larger deviations, with the discrepancy growing rapidly with the overtone number. Moreover, beginning with the second overtone, we observe a striking phenomenon: the real part of the frequency tends to zero quickly as the non-minimal coupling constant increases. This combination of spectral stability in the fundamental mode and high sensitivity of the overtones suggests that the Yang–Mills contribution primarily deforms the metric in the near-horizon region, while the geometry quickly transitions back to a Schwarzschild-like form at larger radii. In addition, we compute the grey-body factors and confirm that they represent a more stable characteristic of the geometry, exhibiting a correspondence with quasinormal modes already at the first multipole. The Yang–Mills coupling enhances the grey-body factors, further increasing the transmission probability.

Czechia

B. Lütfüoğlu

Non-minimal Einstein–Yang–Mills black holes: fundamental quasinormal mode and grey-body factors versus outburst of overtones

In this paper, we discuss the predicted proton lifetimes in minimal supersymmetric (SUSY) $\textit{SU}$(5) grand unified theory (GUT) with gauge mediated supersymmetry breaking (GMSB). We focus on the case of $$\textbf{5} + \bar{\textbf{5}}$$ messengers and determine the low-scale mass spectrum of the scalar particles and gauginos using the renormalization group equations. With the obtained mass spectrum, we calculate the dominant proton decay mode for SUSY $\textit{SU}$(5) GUT, $$p \rightarrow K^+ \bar{\nu }$$ . In our setup, we assume the messenger scale to be $$\mathcal {O}(10^3)$$ TeV in order to obtain a proper Higgs mass in GMSB scenario. For this messenger scale, we find the proton lifetime is consistent with current experimental limits and can be tested by future proton decay experiments.

China

Jason Evans

Yoshihiro Shigekami

Proton Lifetime in Minimal Supersymmetric SU(5) with Gauge Mediation

In this paper, we investigate the shadow and optical appearance of the hairy Kerr black hole illuminated by a thin accretion disk. The deformation parameter $$\alpha $$ and hair parameter $$l_o$$ are found to influence the motions of accretion as well as the redshift effect of the photon, such that they significantly affect the shadow and image of the hairy Kerr black hole. In particular, $$l_o$$ suppresses the shadow size of the black hole while $$\alpha $$ enhances it. We then analyze the widths of the direct, lensed ring and photon ring emission regions for the thin accretion disk. It is found that the widths of the direct emission and lensed ring emission change slightly with the parameters, whereas the width of the photon ring emission increases dramatically as $$l_o$$ decreases. This feature provides more favorable conditions for observing the photon rings of black hole. Finally, we study the redshift of the direct and lensed images, showing that the maximal blueshift point is shifted by the change of the parameters. We argue that our study provides a preliminary theoretical prediction that the image of the hairy Kerr black hole, especially the photon ring structure, may be used to constrain the hair parameters with future high-precision astronomical observation.

Yuan Meng

Xi-Jing Wang

Yong-Zhuang Li

Xiao-Mei Kuang

Effects of hair on the image of a rotating black hole illuminated by a thin accretion disk

The 1 + 3-de Sitter space, as a solution of Einstein’s equations, provides a framework for investigating various physical concepts, including quantum mechanics. In this context, the group Sp(2,2) plays a crucial role as the universal covering of the de Sitter space, contributing significantly to the understanding of associated quantum mechanics. In this study, the presentation of infinitesimal generators of the group Sp(2,2) and quantum operators on the de Sitter space is conducted using the coherent states quantization method, also known as Berezin’s quantization method. This approach allows for a systematic examination of the generators and operators within the quantum framework. Furthermore, the exploration of these generators and operators is facilitated by the unitary representation of the principal series of the group Sp(2,2), offering insights into the underlying quantum mechanics principles governing the de Sitter space.

Iran

A. Rabeie

Infinitesimal generators and quantum operators in de Sitter space

The Electron-Ion Collider in China (EicC), a proposed high-luminosity facility with advanced charged particle and photon detection capabilities, provides unique opportunities to uncover new physics beyond the Standard Model. We analyze its sensitivity to dark photons produced through electron bremsstrahlung in coherent scattering. Thanks to its beam energy settings, it has the potential to comprehensively probe the previously unexplored parameter space between the constraints from meson decays and beam dumps below $$ \mathcal{O}(1) $$ GeV with displaced-vertex search. Additionally, the EicC has the potential to probe axion-like particles (ALPs) in the mass range 0$\textit{.}$1 GeV ≲ $\textit{m}$ ≲ 5 GeV, with a coupling reach of Λ ≲ 10 GeV, by combining the prompt-decay and displaced-vertex searches. The projected sensitivities to ALPs exceed the current bounds.

Qiyuan Gao

Dan Lin

Israel

United States

Hongkai Liu

Teng Ma

Dark photons and axion-like particles at the electron-ion collider in China

Recent work on the quantum mechanics of near-extremal non-supersymmetric black holes has identified a characteristic $\textit{T}$ scaling of the low temperature black hole partition function. This result has only been derived using the path integral in the near-horizon region and relies on many assumptions. We discuss how to derive the $\textit{T}$ scaling for the near-extremal rotating BTZ black hole from a calculation in the full black hole background using the Denef-Hartnoll-Sachdev (DHS) formula, which expresses the 1-loop determinant of a thermal geometry in terms of a product over the quasinormal mode spectrum. We also derive the spectral measure for fields of any spin in Euclidean BTZ and use it to provide a new proof of the DHS formula and a new, direct derivation of the BTZ heat kernel. The computations suggest a path to proving the $\textit{T}$ scaling for the asymptotically flat 4d Kerr black hole.

Daniel Kapec

Y. Law

Chiara Toldo

Quasinormal corrections to near-extremal black hole thermodynamics

Quantum informatic quantities such as entanglement entropy are useful in detecting quantum phase transitions. Recently, a new entanglement measure called pseudo-entropy was proposed which is a generalization of the more well-known entanglement entropy. It has many nice properties and is useful in the study of post-selection measurements. In this paper, one of our goals is to explore the properties of pseudo-entropy and study its effectiveness as a quantum chaos diagnostic, i.e., as a tool to distinguish between chaotic and integrable systems. Using various variants of the SYK model, we study the signal of quantum chaos captured in the pseudo-entropy and relate it to the spectral form factor (SFF) and local operator entanglement (LOE).

Germany

Song He

Japan

Pak Lau

Long Zhao

Detecting quantum chaos via pseudo-entropy

Dimensional reduction of gravity theories to $\textit{D}$ = 2 along commuting Killing isometries is well-known to be classically integrable. The resulting system typically features a coset $\textit{σ}$-model coupled to a dilaton and a scale factor of the dimensional reduction. In this article, we construct two families of deformations of dimensionally reduced gravity that preserve the Lax integrable structure.

Mattia Cesàro

Poland

David Osten

Integrable deformations of dimensionally reduced gravity