The European Physical Journal C最新文献

This work explores the universal classification of thermodynamic topology for charged static black holes within the (z=3) Hor̆ava-Lifshitz gravity theory, considering both canonical and grand canonical ensembles. We introduce a new topological subclass, denoted as (ddot{W}^{1-}). This finding expands the existing topological classification, going beyond the five previously defined classes and their respective subclasses. The (ddot{W}^{1-}) subclass presents a distinct and previously unobserved stability profile: In the low-temperature regime, an unstable small black hole appears in the phase space, whereas, while in the high temperature regime, two unstable small black holes exist together with a stable large black hole. Our study underscores the dependence of charged black hole stability on the selection of the ensemble. These results contribute to refining and expanding the topological framework in black hole thermodynamics, providing key perspectives on the underlying nature of black holes and gravity.

In the present work, we perform a combined analysis of the cross sections for (e^+ e^- rightarrow K^+ K^-) and (e^+ e^- rightarrow K_S^0 K_L^0) by including the interference between direct coupling process and resonance intermediate process. When setting the isospin factor as a free parameter, we can well reproduce the structures in the cross sections for (e^+ e^- rightarrow K^+ K^-) and (e^+ e^- rightarrow K_S^0 K_L^0,) however, the isospin factor deviates with the isospin symmetry conservation predicted value of one. By fixing the isospin factor to be one, we find the cross sections for (e^+ e^-rightarrow K^+ K^-) can be accurately fitted, while the same model parameters fail to adequately reproduce the observed cross section for the process (e^+ e^- rightarrow K_S^0 K_L^0,) which indicate that there should be contributions from other vector meson states, such as (rho (2150)) and (omega (2220).) The combined analysis with (phi (2170),) (omega (2220)) and (rho (2150)) indicate that the inclusion of (rho (2150)) can improve the descriptions of the cross sections for (e^+ e^-rightarrow K^+ K^-) and (e^+ e^- rightarrow K_S^0 K_L^0.)

We derive and analyze a Schwarzschild-like Anti-de Sitter (AdS) (BH) obtained as a static, spherically symmetric solution of Einstein’s equations sourced by a cloud of strings (CoS) and a dark matter (DM) halo modeled by a Dehnen-type density profile. We first study the geodesic motion of massless and massive test particles, emphasizing how the CoS parameter (alpha ) and the DM halo parameters ((rho _s,r_s)) influence photon spheres, circular orbits, the BH shadow, and the innermost stable circular orbit (ISCO). We then examine scalar perturbations via the effective potential and the associated quasinormal-mode (QNM) spectra, showing how (alpha ) and ((rho _s,r_s)) deform oscillation frequencies and damping rates, thereby affecting stability diagnostics. Furthermore, we investigate the thermodynamics in the extended phase space, deriving the Hawking temperature, equation of state, Gibbs free energy, and specific heat capacity, and establishing a consistent first law and Smarr relation with natural work terms for (alpha ) and ((rho _s,r_s).) We find that the interplay between the CoS and the DM halo produces quantitative and sometimes qualitative changes in both dynamical and thermodynamic properties, including shifts in the Hawking–Page transition and heat-capacity divergences, thereby reshaping the phase structure of Schwarzschild–AdS BHs.

In this paper, we have studied the consequences of some representative neutrino flavor-symmetry models for tri-resonant leptogenesis (which is realized by having three nearly degenerate right-handed neutrinos). To be specific, we have considered a neutrino flavor-symmetry model realizing the TM1 mixing and modular (textrm{A}_4), (textrm{S}_4) and (textrm{A}_5) symmetry models that have a right-handed neutrino mass matrix (M_{textrm{R}}) as shown in Eq. (6) which gives three exactly degenerate right-handed neutrino masses and consequently prohibits the leptogenesis mechanism to work successfully. For these models, we study the scenario that the desired right-handed neutrino mass splittings for leptogenesis to work are generated from the renormalization-group running effects. In such a scenario, we explore the parameter space that allows for the reproduction of the observed baryon-antibaryon asymmetry of the Universe.

In this article, the electroweak transition form factors of (Lambda _brightarrow Lambda _c) and (Xi _brightarrow 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 _brightarrow Lambda _clbar{nu }_l) and (Xi _brightarrow Xi _clbar{nu }_l) ((l=e,mu ) and (tau )). Our results for the branching ratios of (Lambda _brightarrow Lambda _clbar{nu }_l) are comparable with experimental data and the results from other collaborations. In addition, our prediction for the branching ratio of (Xi _brightarrow Xi _clbar{nu }_l) can provide a valuable reference for future experimental measurements.

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.

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}(rle 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 tidal charged 4d braneworld black holes of string theory, when the mass in the conjecture is the same quasi-local mass.

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 (rge 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 (rge 10^{-2}). However, non-detection of primordial gravitational waves by LiteBIRD, Simons Observatory and CMB-S4 will potentially rule out quasi-exponential model.

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.

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.