Fortschritte Der Physik-Progress of Physics最新文献

The cover picture shows a particular Mandelbrot fractal, which nicely describes a chaotic system in physics.

(Cover image © Astronira/Shutterstock)

In the K-essence Vaidya Schwarzschild spacetime, the dynamical horizon equation to measure the mass-loss due to Hawking radiation and the tunneling formalism (Hamilton-Jacobi method) to calculate the hawking temperature is applied. Assuming the Dirac-Born-Infeld kind of non-standard action for the K-essence here, the background physical spacetime is a static spherically symmetric black hole, and the K-essence scalar field to be a function only of either forward or backward time is constrained. The K-essence emergent gravity and the generalizations of Vaidya spacetime have been linked by Manna et al. In this paper, Sawayama's modified description of the dynamical horizon to show that the obtained findings deviate from the standard Vaidya spacetime geometry are used.

In this paper, a non-interacting scalar field cosmology with an arbitrary potential using the f-deviser method that relies on the differentiability properties of the potential is investigated. Using this alternative mathematical approach, a unified dynamical system analysis at a scalar field's background and perturbation levels with arbitrary potentials is presented. For illustration, a monomial and double exponential potential is considered. These two classes of potentials comprise the asymptotic behavior of several classes of scalar field potentials, and, therefore, they provide the skeleton for the typical behavior of arbitrary potentials. Moreover, the linear cosmological perturbations in the matterless case by considering three scalar perturbations: the evolution of the Bardeen potentials, the comoving curvature perturbation, the so-called Sasaki-Mukhanov variable, or the scalar field perturbation in uniform curvature gauge is analyzed. Finally, an exhaustive dynamical system analysis for each scalar perturbation is presented, including the evolution of Bardeen potentials in the presence of matter.

Black holes (BHs) convey information about different matter-energy distributions in their immediate environment, as they bear the imprints of the intrinsic spacetime geometry and exotic surrounding matter. In this regard, exact spherically symmetric regular black hole (BH) solutions supported by two phenomenological distributions of dark matter galactic halos in Eintein-Gauss-Bonnet gravity are explored. Analytical solutions for the metric and the corresponding thermodynamic properties, including heat capacity ($�C_{+}$), Gibbs' free energy ($�F_{+}$), and Hawking temperature ($�T_{+}$) associated with the BH's horizon radius and quasinormal modes (QNMs) are found. The specific heat is investigated, and it is discovered that a Hawking-Page phase transition with divergent $�C_{+}$ occurred at a critical radius, $�r_{+}^c$. Consequently, the authors have regular BHs with Cauchy and event horizons, and evaporation results in thermodynamically stable double-horizon BH remnants with zero temperatures. The QNMs of the scalar field perturbations on the regular background of the BHs are then discussed comprehensively.

The interaction energy between two atoms is crucially dependent on the quantum state of the two-atom system. In this paper, it is demonstrated that a steady resonance interaction energy between two atoms exists when the atoms are in a certain type of coherent superposition of single-excitation states. The interaction is tree-level classical in the sense of the Feynman diagrams. A quantity called quantum classicality is defined in the present paper, whose nonzero-ness ensures the existence of this interaction. The dependence of the interatomic interaction on the quantum nature of the state of the two-atom system may potentially be tested with Rydberg atoms.

The species scale provides an upper bound for the ultraviolet cutoff of effective theories of gravity coupled to a number of light particle species. Modular invariant (super-)potentials provide a simple and computable expression of the species scale as a function of the moduli in toroidal orbifold compactifications of type II and heterotic string are pointed out. Due t o modular symmetry, these functions are valid over all moduli space and not only in asymptotic regions. Additive logarithmic corrections to the species scale arise from the requirement that the latter be modular invariant are observed. The moduli-dependent expression of the species scale in terms of the gravitino mass or the scalar potential of these models are recasted and swampland conjectures such as the anti-de Sitter distance conjecture and the gravitino conjecture are connected.

It is shown in this article that an explicit construction of a four-dimensional de Sitter space may be performed using a diagrammatic approach via nodal diagrams emanating from the path integral representation of the Glauber-Sudarshan state. Sum of these diagrams typically leads to an asymptotic series of Gevrey kind which can then be Borel resummed, thus reproducing the non-perturbative structure of the system. The analysis shows that four-dimensional de Sitter space is not only possible in string theory overcoming the no-go and the swampland criteria—albeit as a Glauber-Sudarshan state—but it may also be non-perturbatively stable within a controlled temporal domain. Somewhat consistently, the Borel resummation of the Gevrey series provides strong hint towards the positivity of the cosmological constant.