We constructed a four-Higgs-doublet model (4HDM) invariant under $\textit{D}$ $_{5}$ symmetry and investigated its complete neutral vacuum structure in detail. Assuming explicit CP conservation in the scalar potential, we examined whether CP symmetry can be spontaneously broken. We provided a complete list of all possible real and complex vacua, along with the constraints on the potential parameters required for each vacuum solution to exist. We also discussed the positive-definiteness conditions that the Hessian must satisfy for each vacuum to be a local minimum of the potential. The results show that, after spontaneous symmetry breaking, some complex vacua lead to spontaneous CP violation in the potential, whereas the remaining complex vacua still preserve CP conservation. Among these CP-violating complex vacua, one can be regarded as the most general form. Furthermore, we discussed the relationship between real and complex vacua.

China

Dong-Ping Fu

Michihisa Takeuchi

Spontaneous CP violation in the $\textit{D}$ $_{5}$-symmetric four-Higgs-doublet models * Supported by the Fundamental Research Funds for the Central Universities, the One Hundred Talent Program of Sun Yat-sen University, China, and the Guangdong Natural Science Foundation (2026A1515012641)

In the present work, the strong decays of the discovered $ P_c(4380) $ , $ P_c(4440) $ , $ P_c(4457) $ and their possible isospin cousins are systematically studied via the assignment that they are meson-baryon molecular states. In detail, the strong decay constants and partial decay widths of their decay channels are calculated under the framework of QCD sum rules. The decay widths of the discovered $ P_c(4380) $ , $ P_c(4440) $ , and $ P_c(4457) $ are in good agreement with the experiments. The predictions of the decays of these three related possible isospin cousins are presented, which would shed light on their findings in experiments. In return, this may testify to the assignments of the discovered $ P_c $ states.

Xiu-Wu Wang

Xin Li

Zhi-Gang Wang

Systematic study of the strong decays of the $\textit{P}$ $\textit{c}$ states and their possible isospin cousins via the QCD sum rules * Supported by the National Natural Science Foundation of China (12575083) and the Natural Science Foundation of Hebei Province (A2024502002)

In this work, we investigate three representative new-physics resonances that couple to Standard Model (SM) quarks through flavor-changing interactions involving the top quark. We identify the possible SMEFT operators at the electroweak scale and analyze their phenomenology.

Min Huang

Yandong Liu

Hao Zhang

Exploring new resonances with direct top flavor changing interactions * Min Huang and Hao Zhang is supported in part by the National Science Foundation of China (12575114, 12235001, 12075257)

The exploration of symmetry laws stands as a cutting-edge direction in modern physics research. This study delves into the examination of $\textit{P}$ and $\rm CP$ symmetry properties within the charm quark system by analyzing asymmetry parameters in the two-body decay process of $ \Omega_c $ . By accounting for the polarization effects of electron and positron beams and employing the helicity formalism, we systematically analyze the decay characteristics of $ \Omega_c $ and its subsequent hyperon decays through specific asymmetry parameters. A comprehensive formulation of the angular distribution for these decay processes has been developed. The research assesses the detection sensitivity of asymmetry parameters in the $ \Omega_c\rightarrow \Omega^-\pi^+ $ decay mode across different experimental conditions, including varying data sample sizes and beam polarization configurations. These results contribute to enriching a theoretical foundation for forthcoming experimental endeavors at the STCF, offering significant implications for symmetry studies in the charm sector.

Yunlu Wang

Yunlong Xiao

Pengcheng Hong

Phenomenological study of Ω $\textit{c}$ → Ω$^{−}$ $\textit{π}$ $^{+}$ at polarized electron-positron collider

Hadron-hadron interactions, being nonperturbative in nature, play a significant role in addressing phenomenological questions in particle physics. Femtoscopy is a powerful tool in heavy-ion collision experiments, enabling the extraction of hadron-hadron interactions via momentum-correlation functions (CFs). These CFs are typically expressed as a convolution of source functions and hadron-hadron wave functions, with the latter encoding information about the interactions. However, source functions remain poorly constrained and are commonly approximated by a Gaussian form. Reconstructing source functions from experimental correlation data constitutes an 'inverse problem.' To address this, we propose a toy model based on Tikhonov regularization. Using a square-well potential with four distinct strengths, we calculate the CFs for inputs of single Gaussian source functions and mixed Gaussian source functions. The resulting CFs are then used to reconstruct the source functions via Tikhonov regularization. Our results show that the Gaussian source function can be successfully reconstructed, highlighting the potential of this approach for extracting realistic source functions from hadron pairs of interest.

Ao-Sheng Xiong

Qi-Wei Yuan

Ming-Zhu Liu

Fu-Sheng Yu

Zhi-Wei Liu

Li-Sheng Geng

Solving the inverse source problem in femtoscopy with a toy model * Supported in part by the Fundamental and Interdisciplinary Disciplines Breakthrough Plan of the Ministry of Education of China (JYB2025XDXM204) and the National Natural Science Foundation of China (W2543006, 12435007). Ming-Zhu Liu acknowledges support from the National Natural Science Foundation of China (12575086). Zhi-Wei Liu acknowledges support from the National Natural Science Foundation of China (12405133) and from the Shenzhen Science and Technology Program (ZDSYS20230626091501002). Fu-Sheng Yu and Ao-Sheng Xiong acknowledge support from the Scientific Research Innovation Capability Support Project for Young Faculty (ZYGXQNJSKYCXNLZCXM-P2) and from the Fundamental Research Funds for the Central Universities (lzujbky-2023-stlt01, lzujbky-2024-oy02, lzujbky-2025-eyt01)

We present a comprehensive study of the spectra and radiative decays of the triply heavy baryons $$\Omega _{ccc}$$ and $$\Omega _{bbb}$$ within a quark–diquark framework using a screened potential model. The analysis is carried out by solving a relativized Hamiltonian for a two–body bound system: the diquark masses are first determined, after which each baryon is treated as a composite of the diquark and the third quark. Employing the obtained wave functions, we calculate electromagnetic transitions using the E1 and M1 operators. We report mass spectra together with E1/M1 decay widths for radially and orbitally excited states, and systematically compare our results with those from other theoretical approaches.

India

Chaitanya Bokade

Bhaghyesh Azhothkaran

Spectroscopy and radiative decays of $$\Omega _{ccc}$$ and $$\Omega _{bbb}$$ baryons in a quark–diquark model

We present an exact analytical model describing a complete gravitational collapse of matter from horizonless initial conditions to black hole formation, tracing the full evolution of the horizon $\textit{H}$($\textit{t}$) from its formation at microscopic scales to macroscopic stabilization. The solution reveals two main stages: (i) a dynamical horizon growth, where an apparent horizon $\textit{H}$($\textit{t}$) emerges at a critical time $$t_b$$ until reaching its final size $$h=2\mathcal{M}$$ , demonstrating how trapped surfaces form dynamically in finite time, and (ii) a naked-singularity resolution, where an integrable Ricci curvature singularity ( $$R^\mu {}_\nu \sim r^{-2}$$ ) develops at $$r=0$$ , but remains causally hidden by the horizon growth, preserving weak cosmic censorship without exotic matter. The model could offer a framework to study the quantum-to-classical transition ( $$H(t) \sim \ell _\textrm{Planck}$$ ).

Japan

Sinya Aoki

Czechia

Chile

Jorge Ovalle

An analytic model for a total process of gravitational collapse: from star to Schwarzschild black hole

Matter-energy accretion phenomena onto astrophysical compact objects interpolate between local and global scales of our universe. In this paper, we will investigate the slow steady-state matter-energy accretion onto some black holes performing a comparative analysis with respect to both their gravitational potentials and for different accretion models whose applicability will be scrutinized. We will identify some mimicking of the Schwarzschild mass evolution and locations of the sonic critical points, the latter obtained via the continuity equation and the Bernoulli theorem. After analyzing these general features of the set-up, we will specialize to a cosmic matter supporting an emergent universe. Our analysis, fully based on exact analytical computations, will clarify the different roles of the small-scale astrophysical degrees of freedom, encoded in the black hole redshift and shape functions, versus the large-scale cosmological ones of the accreted material. Our manuscript tackles the intricate dynamics taking place across galactic and cosmological regimes, where screening mechanisms may occur, pointing out the required observational information for conclusively claiming the physical nature of an astrophysical compact object.

Daniele Gregoris

Bondi–Hoyle–Lyttleton accretion: on the roles of shape and redshift functions

We study the sensitivity of displaced vertex searches at the LHC to heavy neutral leptons (also known as sterile neutrinos) that are produced in pairs with an electroweak-size cross section. We work within the context of a supersymmetric model in which the sterile neutrino is produced along with Standard Model particles in higgsino decays. By making use of model-independent reconstruction efficiencies provided by the ATLAS collaboration in their search for displaced vertices with multiple jets, we obtain constraints on this model from 139 fb of data collected by ATLAS during the LHC Run 2, and assess the discovery reach of Run 3 and of the high-luminosity LHC (HL-LHC). Depending on the higgsino mass parameter, sterile neutrino masses between 20 GeV and 230 GeV and active-sterile neutrino mixings in the range 4 × 10 ≲ $$ {V}_N^2 $$ ≲ 3 × 10 can be excluded. At the HL-LHC, discovery-level significances could be reached for sterile neutrinos masses up to 295 GeV and values of $$ {V}_N^2 $$ down to 3 × 10 . Finally, moving away from the supersymmetric scenario, we study to which extent these results can be generalized to a broader class of models in which the sterile neutrinos are produced in the decays of heavier particles that are themselves pair-produced with an electroweak-size cross section.

France

Stéphane Lavignac

Argentina

Anibal Medina

Nicolás Mileo

Santiago Tanco

Probing electroweak pair production of heavy neutral leptons with displaced vertices at the LHC

We demonstrate that a vector-like fourth family of quarks induces a genuine chiral enhancement in $\textit{b}$ → $\textit{sγ}$, which is absent in the Standard Model (SM). The coexistence of doublet and singlet states allows the chirality flip to occur inside the loop, leading to contributions proportional to the heavy vector-like mass. The resulting amplitude is enhanced by a factor $$ {\overline{\lambda}}_d{v}_H/{m}_b $$ , which can be as large as $$ \mathcal{O}(40) $$ for moderate Yukawa couplings. This leads to sizable deviation from the SM prediction even for $$ \mathcal{O}\left(\mathrm{TeV}\right) $$ vector-like quark masses and small mixing angles. We find that $$ \mathrm{Br}\left(\overline{B}\to {X}_s\gamma \right) $$ provides the most stringent constraint on this scenario among a wide range of precision observables.

Junichiro Kawamura

Yuji Omura

Chiral enhancement in the vector-like fourth family: case of $\textit{b}$ → $\textit{sγ}$