Search

The article presents a study that examines the nonlinear Breit-Wheeler process of the pair production of electron and positron off a probe photon that collides with two electromagnetic waves that propagate in the same direction. The researchers also investigate the probability of the electron-positron pair production for the process. They observe that the contributions of the low-frequency electromagnetic wave to such probability can be enhanced through the presence of a high-frequency wave.

Due to the nonindependence of entropy and thermodynamic volume for spherically symmetric black holes in the anti-de Sitter (AdS) spacetime, when applying the Ruppeiner thermodynamic geometry theory to these black holes, we often encounter an unavoidable problem of the singularity about the line element of thermodynamic geometry. In this paper, we propose a basic and natural scheme for dealing with the thermodynamic geometry of spherically symmetric AdS black holes. We point out that enthalpy, not internal energy, is the fundamental thermodynamic characteristic function for the Ruppeiner thermodynamic geometry. Based on this fact, we give the specific forms of the line element of thermodynamic geometry for the Schwarzschild AdS (SAdS) black hole in different phase spaces, and the results show that the thermodynamic curvatures obtained in different phase spaces are equivalent. It is shown that the thermodynamic curvature is negative which may be related to the information of attractive interaction between black hole molecules for the SAdS black hole. Meanwhile we also give an approximate expression of the thermodynamic curvature of the Schwarzschild black hole which shows that the black hole may be dominated by repulsion on the low temperature region and by attraction on the high temperature region phenomenologically or qualitatively. [ABSTRACT FROM AUTHOR]

A time evolving fluid system is constructed on a timelike boundary hypersurface at finite cutoff in Vaidya spacetime. The approach used to construct the fluid equations is a direct extension of the ordinary gravity/fluid correspondence under the constrained fluctuation obeying Petrov type I conditions. The explicit relationships between the time dependent fluctuation modes and the fluid quantities such as density, velocity field and kinematic viscosity parameters are established, and the resulting fluid system is governed by a system of a sourced continuity equation and a compressible Navier-Stokes equation with nontrivial time evolution. [ABSTRACT FROM AUTHOR]

Using deep inelastic scattering on a large nucleus as an example, we consider the transverse momentum broadening of partons in hard processes in the presence of medium. We find that one can factorize the vacuum radiation contribution and medium related PT broadening effects into the Sudakov factor and medium dependent distributions, respectively. Our derivations can be generalized to other hard processes, such as dijet productions, which can be used as a probe to measure the medium PT broadening effects in heavy ion collisions when Sudakov effects are not overwhelming. [ABSTRACT FROM AUTHOR]

We study the Boltzmann equation with elastic pointlike scalar interactions in two different versions of the classical approximation. Although solving numerically the Boltzmann equation with the unapproximated collision term poses no problem, this allows one to study the effect of the ultraviolet cutoff in these approximations. This cutoff dependence in the classical approximations of the Boltzmann equation is closely related to the nonrenormalizability of the classical statistical approximation of the underlying quantum field theory. The kinetic theory setup that we consider here allows one to study in a much simpler way the dependence on the ultraviolet cutoff, since one also has access to the nonapproximated result for comparison. [ABSTRACT FROM AUTHOR]