General Relativity and Gravitation最新文献

In this short paper, we investigate the consequences of observer dependence of the quantum effective potential for an interacting field theory. Specializing to (d+2) dimensional Euclidean Rindler space, we develop the formalism to calculate the effective potential. While the free energy diverges due to the presence of the Rindler horizon, the effective potential, which is a local function of space, is finite after the necessary renormalization procedure. We apply the results of our formalism to understand the restoration of spontaneously broken (mathbb {Z}_2) symmetry in three and four dimensions.

We shall investigate the inflation for the D-brane model, motivated by the modified gravity (F(phi ,T)). This gravity has been recently introduced in the literature. The feasibility of the D-brane inflation theory in the (F(phi ,T))-gravity has been studied in conjunction with the most recent Planck data. We shall analyze the slow-roll inflation in the context of the (F(phi )T)-gravity, via the D-brane model. Then, we shall calculate the inflation dynamics to obtain the scalar spectral index “(n_s)” and the tensor-to-scalar ratio “r”. Besides, we investigate the dynamics of the reheating for this model. Our model accurately covers the left-hand side of the Planck data and the D-brane inflation.

We present a novel approach for calculating the gravitational self-force (GSF) in the Lorenz gauge, employing hyperboloidal slicing and spectral methods. Our method builds on the previous work that applied hyperboloidal surfaces and spectral approaches to a scalar-field toy model [Phys. Rev. D 105, 104033 (2022)], extending them to handle gravitational perturbations. Focusing on first-order metric perturbations, we address the construction of the hyperboloidal foliation, detailing the minimal gauge choice. The Lorenz gauge is adopted to facilitate well-understood regularisation procedures, which are essential for obtaining physically meaningful GSF results. We calculate the Lorenz gauge metric perturbation for a secondary on a quasicircular orbit in a Schwarzschild background via a (known) gauge transformation from the Regge-Wheeler gauge. Our approach yields a robust framework for obtaining the metric perturbation components needed to calculate key physical quantities, such as radiative fluxes, the Detweiler redshift, and self-force corrections. Furthermore, the compactified hyperboloidal approach allows us to efficiently calculate the metric perturbation throughout the entire spacetime. This work thus establishes a foundational methodology for future second-order GSF calculations within this gauge, offering computational efficiencies through spectral methods.

A class of f(R, T) theories extends the Einstein-Hilbert action by incorporating a general function of R and T, the Ricci scalar and the trace of the ordinary energy-momentum tensor (T_{mu nu }), respectively, thereby introducing a specific modification to the Einstein’s field equations based on matter fields. Given that this modification is intrinsically tied to an energy-momentum tensor (T_{mu nu }) that a priori respects energy conditions, we explore the potential of f(R, T) theories admitting wormhole configurations satisfying energy conditions, unlike General Relativity, which typically necessitates exotic matter sources. Consequently, we investigate the existence of dynamical wormhole geometries that either uphold energy conditions or minimize their violations within the framework of trace of energy-momentum tensor squared gravity. To ensure the generality of our study, we consider two distinct equations of state for the matter content and systematically classify possible solutions based on constraints related to the wormhole’s throat size, the coupling parameter of the theory, and the equation of state parameters.

In this paper, we determine the relativistic bound-state solutions for the charged (DO) Dirac oscillator in a rotating frame in the Bonnor-Melvin-Lambda spacetime in ((2+1))-dimensions, where such solutions are given by the two-component normalizable Dirac spinor and by the relativistic energy spectrum. To analytically solve our problem, we consider two approximations, where the first is that the cosmological constant is very small (conical approximation), and the second is that the linear velocity of the rotating frame is much less than the speed of light (slow rotation regime). After solving a second-order differential equation, we obtain a generalized Laguerre equation, whose solutions are the generalized Laguerre polynomials. Consequently, we obtain the energy spectrum, which is quantized in terms of the radial and total magnetic quantum numbers n and (m_j), and depends on the angular frequency (omega ) (describes the DO), cyclotron frequency (omega _c) (describes the external magnetic field), angular velocity (Omega ) (describes the rotating frame), spin parameter s (describes the “spin”), spinorial parameter u (describes the components of the spinor), effective rest mass (m_{eff}) (describes the rest mass modified by the spin-rotation coupling), and on a real parameter (sigma ) and cosmological constant (Lambda ) (describes the Bonnor-Melvin-Lambda spacetime). In particular, we note that this spectrum is asymmetrical (due to (Omega )) and has its degeneracy broken (due to (sigma ) and (Lambda )). Besides, we also graphically analyze the behavior of the spectrum and of the probability density as a function of the parameters of the system for different values of n and (m_j).

We study quasinormal mode expansions by adopting a Keldysh scheme for the spectral construction of asymptotic resonant expansions. Quasinormal modes are first cast in terms of a non-selfadjoint problem by adopting, in a black hole perturbation setting, a spacetime hyperboloidal approach. Then the Keldysh expansion of the resolvent, built on bi-orthogonal systems, provides a spectral version of Lax-Phillips expansions on scattering resonances. We clarify the role of scalar product structures in the Keldysh setting [1], that prove non-necessary to construct the resonant expansions (in particular the quasinormal mode time-series at null infinity), but are required to define the (constant) excitation coefficients in the bulk resonant expansion. We demonstrate the efficiency and accuracy of the Keldysh spectral approach to (non-selfadjoint) dynamics, even beyond its limits of validity, in particular recovering Schwarzschild black hole late power-law tails. We also study early dynamics by exploring i) the existence of an earliest time of validity of the resonant expansion and ii) the interplay between overtones extracted with the Keldysh scheme and regularity. Specifically, we address convergence aspects of the series and, on the other hand, we implement non-modal analysis tools, namely assessing (H^p)-Sobolev dynamical transient growths and constructing (H^p)-pseudospectra. Finally, we apply the Keldysh scheme to calculate “second-order” quasinormal modes and complement the qualitative study of overtone distribution by presenting the Weyl law for the counting of quasinormal modes in black holes with different (flat, De Sitter, anti-De Sitter) spacetime asymptotics.

Correction to: Geometrical Origin of the Cosmological Constant, Gen. Relativ. Gravit. 44, 2547-2561 (2012). https://doi.org/10.1007/s10714-012-1413-9