The European Physical Journal C最新文献

We investigate the nonlinear dynamics of black holes in an Einstein-scalar-Gauss-Bonnet (EsGB) gravity theory where a real scalar field couples to both the Gauss-Bonnet invariant and the Ricci scalar through a higher-order coupling function. Starting from both bald and hairy static solutions, we perform full numerical simulations in Painlevé–Gullstrand-like coordinates to follow the time evolution triggered by localized scalar field pulses. We identify the scalarization threshold of the static solutions and uncover four distinct dynamical channels: stable Schwarzschild black holes resisting scalar growth; spontaneous scalarization of Schwarzschild black holes into stable hairy configurations; transitions between metastable and stable hairy states; and complete descalarization of metastable or weakly perturbed hairy black holes back to the Schwarzschild phase. Energy redistribution is quantified using the Misner–Sharp mass, which reveals horizon mass growth and energy transport. The effective stress-energy tensor violates the null convergence condition during scalarization, indicating regions of negative effective energy that support hair formation. Our results demonstrate that scalarized black holes emerge naturally as nonlinear end states of evolution in EsGB gravity, and they highlight the rich phase-space structure and dynamical behavior beyond general relativity.

This paper studies the impact of bulk viscosity on the feasibility of the cosmological bounce solutions in the framework of F(R) theory. In this perspective, the behavior of an isotropic homogeneous universe with a perfect matter configuration and new formulation of the bulk viscosity coefficient is explored. We select a specific mathematical form of the modified gravity model to see how it affects the dynamics of cosmic evolution. In addition, we analyze various cosmological parameters, exploring the presence of feasible cosmological bounce solutions. A physically acceptable bouncing scenario occurs when the energy density stays positive, pressure becomes negative, and the violation of null and strong energy conditions highlight the important role of bulk viscosity. We also study the cosmographic parameters and their paths in the (r-s) diagnostic framework. Finally, a thermodynamic investigation is carried out to test the generalized second law of thermodynamics and the overall stability of the cosmological model. The results show that F(R) gravity is a realistic and promising alternative to the standard cosmological model, giving deeper understanding of gravitational dynamics and the early evolution of cosmos.

We investigate non-perturbative bulk corrections arising from instantons in string theory and M-theory. By deriving non-local curvature corrections of the form ( e^{-gamma R} R_{mu nu } R^{mu nu } ), we demonstrate how these modifications emerge from wrapped brane instantons and their summation over multi-instanton configurations. Utilizing holographic techniques, we establish a direct connection between these non-perturbative effects and large-( N ) gauge theories, identifying the appropriate holographic dual conformal field theory (CFT). We further analyze this connection through resummations in the large-( N ) expansion. Additionally, we study black hole solutions in AdS backgrounds and show that these instanton-induced corrections significantly modify the near-horizon geometry. Finally, we explore the regularization of curvature singularities via these exponential damping terms, providing a natural resolution mechanism in quantum gravity. Our findings underscore the fundamental role of non-perturbative physics in shaping the structure of spacetime and its holographic duals.

We explore the potential manifestation of a hexaquark, the H particle, as a constituent within neutron stars. The H particle, with a quark content of uuddss, is constructed within the Chromomagnetic Interaction (CMI) framework. Specifically, we contemplate the flavor-singlet state H with (J^P=0^+). Our computations indicate that the three-flavor hexaquark state, the H particle, possesses a lower mass of (2212.7~textrm{MeV}) in comparison to the (d^*(2380)), implying greater stability than the two-flavor (d^*(2380)). The analysis involving the H particle is carried out using the relativistic mean-field (RMF) model. We investigate the influence of H particle couplings, a key factor in determining the system stability, and focus on the potential existence of H particle within neutron stars. We find that H particle could potentially endure as a stable constituent within neutron stars, and lead to a reduction of the maximum mass.

We start from a Lorentzian action in a deformed light-cone background and applying the method of null reduction leads to a Carrollian action in one lower spacetime dimensions. We also identify the correct light-cone definitions of the symmetry generators and their dynamical forms in terms of the fields and take the (crightarrow 0) limit. It is observed that these generators produce the known kinematic Carrollian conformal algebraic commutation relations.

We investigate charged Dirac quasinormal spectra on Reissner–Nordström black holes in a mirror-like cavity. For this purpose, we first derive charged Dirac equations, and two sets of Robin boundary conditions following the vanishing energy flux principle. The Dirac spectra are then computed both analytically and numerically. Our results reveal a symmetry hidden in the Dirac spectra between two boundary conditions. Moreover, when the cavity is placed close to the event horizon (r_+), we identify that, in the neutral background the Dirac spectra asymptote to (-(3/8+N/2)i) [(-(1/8+N/2)i)] for the first [second] boundary condition; while in the charged background the real part of charged Dirac spectra asymptote to (qQ/r_+) for both boundary conditions; where N is the overtone number, q and Q are charges for the field and for the background. In particular, we uncover a striking anomalous decay pattern, i.e. the excited modes decay slower than the fundamental mode, when the charge coupling qQ is large. Our results further illustrate the robustness of vanishing energy flux principle, which are applicable not only to anti-de Sitter black holes but also to black holes in a cavity.

The intelligent distributed dispatch and scheduling (iDDS) service is a versatile workflow orchestration system designed for large-scale, distributed scientific computing. iDDS extends traditional workload and data management by integrating data-aware execution, conditional logic, and programmable workflows, enabling automation of complex and dynamic processing pipelines. Originally developed for the ATLAS experiment at the large hadron collider, iDDS has evolved into an experiment-agnostic platform that supports both template-driven workflows and a Function-as-a-Task model for Python-based orchestration. This paper presents the architecture and core components of iDDS, highlighting its scalability, modular message-driven design, and integration with systems such as PanDA and Rucio. We demonstrate its versatility through real-world use cases: fine-grained tape resource optimization for ATLAS, orchestration of large Directed Acyclic Graph (DAG) workflows for the Rubin Observatory, distributed hyperparameter optimization for machine learning applications, active learning for physics analyses, and AI-assisted detector design at the electron–ion collider. By unifying workload scheduling, data movement, and adaptive decision-making, iDDS reduces operational overhead and enables reproducible, high-throughput workflows across heterogeneous infrastructures. We conclude with current challenges and future directions, including interactive, cloud-native, and serverless workflow support.

We study the semileptonic decay of its SU(3) partner, the (Lambda _c rightarrow Lambda ell ^+ nu _ell ) ((ell = e, mu )) transition, within the framework of light-cone QCD sum rules (LCSR) by using the distribution amplitudes of heavy (Lambda _c) baryon. The numerical analysis is performed using two different sets of (Lambda _c) baryon light-cone distribution amplitudes. The resulting form factors are parametrized by a model-independent z-series expansion and used to compute the differential and total decay widths. Our predictions for the branching fractions are in good agreement with the latest BESIII measurements and with lattice-QCD results.

We propose a new extension of the Standard Model that incorporates a gauged ( U(1)_{mathrm{B-L}} ) symmetry and the type-III seesaw mechanism to explain neutrino mass generation and provide a viable dark matter (DM) candidate. Unlike the type-I seesaw, the type-III seesaw extension under ( U(1)_{mathrm{B-L}} ) is not automatically anomaly-free. We show that these anomalies can be canceled by introducing additional chiral fermions, which naturally emerge as DM candidates in the model. We thoroughly analyze the DM phenomenology, including relic density, direct and indirect detection prospects, and constraints from current experimental data. Furthermore, we explore the collider signatures of the model, highlighting the enhanced production cross-section of the triplet fermions mediated by the ( mathrm B-L ) gauge boson, as well as the potential disappearing track signatures. Additionally, we investigate the gravitational wave signals arising from the first-order phase transition during ( mathrm B-L ) symmetry breaking, offering a complementary cosmological probe of the framework.

This investigation develops two exact anisotropic solutions determined by the Chaplygin equation of state within the context of Einstein’s gravity theory using the minimal geometric deformation. In order to accomplish this, we start with the anisotropic fluid acting as the seed source inside a static spherical interior. The gravitational interaction between the additional matter source and the seed (parent) fluid is then included in a Lagrangian that describes a new source. We compute the field equations for the full matter configuration and then transform the radial component to produce two independent systems of equations. Each set is imposed by different constraints that allow them to solve separately and leading to novel solutions. By matching the interior and exterior geometries using the suitable junction conditions, the constants that appear in the interior solutions are determined. The observed mass and radius of the compact star candidates (Vela~X-1) and (Cen~X-3) are then used to graphically examine the resulting models. We show that our solutions fulfill all the physical feasibility requirements for the chosen parameter values, indicating the workability of the gravitational decoupling approach in the current scenario.