Photon emission due to vacuum instability under the action of a quasi-constant electric field

TL;DR

The paper presents a nonperturbative, strong-field QED framework to study photon emission accompanying vacuum instability in a quasi-constant, finite-duration electric field $T$, deriving an effective perturbation theory for radiative processes via the generalized Furry picture. It delivers closed expressions for the total probability of one-photon emission from the vacuum and establishes the domain of applicability for the locally constant field approximation (LCFA) in the high-frequency regime, showing that the formation interval width is set by the field strength $E$ and is largely independent of $\omega$. The work reveals distinct angular and polarization characteristics: high-frequency emission concentrates near the plane orthogonal to the field with two linear polarization channels, and the emission associated with pair creation exhibits cylindrical symmetry and specific polarization weighting. These results provide a robust LCFA foundation for strong-field QED processes and may be extendable to slowly varying fields and, potentially, to Dirac semimetals with small gaps.

Abstract

Following a nonperturbative formulation of strong-field QED developed in our earlier works, we consider photon emission accompanying vacuum instability under the action of a quasi-constant strong electric field of finite duration T. We construct closed formulas for the total probabilities and study the photon emission accompanying an electron-positron pair creation from a vacuum. We establish the domain of the applicability of the locally constant field approximation (LCFA) for the photon emission. We study angular and polarization distribution of the emission as well as emission characteristics in a high-frequency approximations with respect of 1/T. The results presented in this work is suitable to a further development of the LCFA proposed in [Phys. Rev. D 95, 076013 (2017)].