The European Physical Journal Plus最新文献

We present comprehensive calculations of gravitational wave strain amplitudes for known binary pulsar systems, using data from current ground based detectors (LIGO-Virgo-KAGRA) and the upcoming space-based missions (LISA). We present detailed calculations of the characteristic gravitational wave strain values, ranging from 3.0 to 73 (times, 10^{-22}), across frequencies between 0.66 and 5.87 (times, 10^{-4}) Hz. Our post-Newtonian approximation analysis yields predicted periastron advance rates from 1.6 to 80.5 deg/yr and orbital period decay rates between −5 and −176 (upmu)s/yr for the binary pulsar population. We derive common envelope efficiency parameters ((alpha _{rm CE})) for representative progenitor scenarios within our sample, finding values between 0.63 and 1.16, with notable sensitivity to the binding energy parameter (lambda). Binary neutron star merger rates are estimated at (22.77^{+6.83}_{-6.83}) (textrm{Myr}^{-1}) for the Milky Way, corresponding to a volumetric rate of (227.71^{+68.31}_{-68.31}) (textrm{Gpc}^{-3}) (textrm{yr}^{-1}), consistent with the latest LIGO-Virgo-KAGRA observational constraints. Our results illustrate how multi-band gravitational wave observations, from LIGO/Virgo to LISA, can contribute to precise measurements of binary pulsar strain and orbital evolution histories, improving merger time predictions and constraining neutron star physics and common envelope processes.

One of the greatest challenges of theoretical physics today is to unveil the quantum information theory concerning what happens when one bit of information enters the black hole (BH) horizon. The Landauer principle showed that a certain amount of energy is generated when one-bit of information is erased as it enters the event horizon system. In this paper we used the recently developed Barrow BH model to calculate the addition to the area of the event horizon of his toy model by using the Landauer concept. Besides we make this computation considering (Delta) as a constant and a variable parameter. We formulate the Barrow parameter ((Delta)) as a function of the energy/mass, which is new in the Barrow BH literature. We will investigate the differences between the Bekenstein–Hawking entropy ((Delta =0)) and the fractal ((Delta =1)) cases concerning the addition in the area of the BH. The asymptotical analysis is also mentioned and we will see that it affects only the fractal case. All the results accomplished here are new concerning BHs in general and the Barrow model literature in particular.

Site effects are a critical topic in seismology and earthquake engineering, with topographic effects playing a pivotal role in local seismic response. Traditional models often rely on manually selected topographic parameters, such as slope, curvature, or relative elevation, limiting their effectiveness and interpretability. In this study, seismic ground motion in the Erlang Mountain area of the Sichuan–Tibet region, China, was simulated using the spectral element method (SEM). A U-Net-based deep learning model was then employed to predict seismic topographic amplification, taking digital elevation model (DEM) data as input and peak ground velocity (PGV) amplification factors as output. Multi-layer convolution operations extracted topographic features, while skip connections integrated multi-scale information. Quantified by root-mean-square error (RMSE), the U-Net model outperformed traditional back-propagation (BP) neural networks. Incorporating incident angle and subsurface velocity structures as additional input channels further improved prediction accuracy, highlighting the coupled influence of topography and subsurface conditions. This study provides a data-driven framework for simulating seismic topographic effects.

We determine a four-function generalization of the Plebański spacetime, depending on three arbitrary functions of the radial coordinate and one function on the angular coordinate. For the generalized Plebański spacetime, we analyze the separability of the Hamilton–Jacobi equations, and the trajectories of a charged test particle are derived from the motion constants. The Klein–Gordon equation separability is established and the Killing horizons are presented as well. Then we introduce a conformal factor to the Plebański metric and discuss the conditions that preserve the separability. Finally we show a possible stress–energy tensor that may be the source of some of the generalized metrics.

We develop the method for constructing solutions to the nonlocal nonlinear Schrödinger equation (NLSE) with an anti-Hermitian term that are semiclassically localized on a one-dimensional manifold (a curve). The evolution of the curve is given by the closed system of integro-differential equations that can be treated as the “classical”  analog of the open quantum system with the nontrivial geometry. Using our approach, we consider the evolution of vortex states in the open quantum system described by the specific model NLSE. The semiclassical stage of the vortex evolution can be treated as a quasi-steady vortex state. We show that the behavior of this state is largely determined by the geometry of the localization curve.

This study investigates event-by-event dynamical net-charge fluctuations in proton-lead (p-Pb) collisions at (sqrt{s_{NN}}=) 5.02 TeV using the AMPT model in both string-melting and default modes. The analysis focuses on the fluctuation measure (nu _{textrm{dyn}}), its scaled behaviour with respect to pseudorapidity window ((Delta eta )), and the dynamical net-charge fluctuations per unit entropy. Additionally, the strength of fluctuations is studied for identified particle species, including pions, kaons, and protons. A comparative approach with Pb-Pb collisions at (sqrt{s_{NN}}=) 5.5 TeV is employed to differentiate between initial-state effects and final-state interactions, with the aim of probing QGP-like signatures in small collision systems.

We investigate four analytical families of vector quartic solitons (VQS) propagating on a continuous-wave background (CWB) in weakly birefringent optical fibers with (2^{text {nd}}), (3^{text {rd}}), and (4^{text {th}})-order dispersion (OD). The resulting solutions, constructed from smooth combinations of hyperbolic functions, describe localized pulses as well as complementary bright–dark vector pairs. Their formation arises from the joint action of self-phase modulation (SPM), cross-phase modulation (CPM), four-wave mixing (FWM), and higher-order dispersion. Although the four subclasses differ in amplitude, wavenumber, and temporal width, they share a common frequency shift and propagation velocity, both fixed solely by the dispersion parameters. Closed-form algebraic constraints determine the existence ranges, while direct numerical simulations of the extended coupled nonlinear Schrödinger (NLSE) model demonstrate that all four families remain stable and preserve their profiles under additive white-noise perturbations. Altogether, the results provide a unified analytical description of CWB-supported vector quartic solitons and point to new opportunities for dispersion-managed slow-light and ultrafast photonic applications.

This study theoretically investigates the fundamental properties of obliquely propagating dust-ion-acoustic solitary waves in a collisionless magnetized dusty plasma. The system comprises inertial cold ions, negatively charged stationary dust grains, Boltzmann-distributed cold electrons, hot electrons, and hot protons. A Korteweg–de Vries equation is derived using the reductive perturbation method to model the evolution of small-amplitude solitary waves. The analysis reveals that the plasma system supports only positive potential solitary structures, as the nonlinear and dispersion coefficients stay positive over a wide range of plasma parameters. The results indicate that variations in plasma parameters and the angle of obliqueness significantly influence the characteristics of solitary waves. These findings enhance the understanding of wave propagation in both laboratory and space plasma environments under the influence of an external magnetic field.

The paper considers the propagation of coupled gravitational and electromagnetic waves in cold magnetized plasma. It is shown that for the case of plasma refractive index (ngg 1), the energy density flux of the gravitational wave component of coupled gravitational and electromagnetic waves increases significantly. The process of decoupling electromagnetic and gravitational waves during absorption of the electromagnetic component by plasma layer is considered as well.

Classical general relativity predicts curvature singularities within black holes, mathematical infinities widely regarded as artifacts signaling breakdown of the geometric description. While the Schwarzschild and Kerr solutions match all external observations, no consensus exists on the physical interior. Existing approaches to singularity resolution, including limiting curvature hypotheses, emergent-spacetime models, phase transition analogies, and elastic medium formulations, address aspects of this problem but remain disconnected. This paper proposes a unifying mechanical interpretation. Spacetime is treated as a finite-strength substrate supporting metric relations up to a critical stress threshold (sigma _c). The Kretschmann curvature invariant (K = R_{alpha beta gamma delta }R^{alpha beta gamma delta }) is reinterpreted as substrate stress (sigma = sqrt{K}), and when (sigma) reaches (sigma _c), the continuum approximation fails and the medium transitions to a non-metric phase rather than infinite curvature. Event horizons thus mark mechanical failure boundaries where geometric description terminates. All external predictions of general relativity remain unchanged, while the interior is reframed as beyond the domain of continuum geometry. This framework synthesizes geometric, thermodynamic, and mechanical perspectives under a single substrate paradigm, anchoring singularity avoidance to the expected Planck-scale breakdown of spacetime as a continuum.