Pair production in temporally and spatially oscillating fields

TL;DR

This paper investigates electron-positron pair production in complex oscillating electromagnetic fields, using advanced numerical methods to analyze momentum spectra and evaluate the validity of approximation techniques in various regimes.

Contribution

It introduces a detailed numerical analysis of pair production in inhomogeneous, oscillating fields and assesses the applicability of local density approximations in this context.

Findings

Momentum spectra reveal effects of field inhomogeneity.

Local density approximation's validity depends on field parameters.

Linear momentum conservation impacts spectral features.

Abstract

Electron-positron pair production for inhomogeneous electric and magnetic fields oscillating in space and time is investigated. By employing accurate numerical methods (Furry-picture quantization and quantum kinetic theory), final particle momentum spectra are calculated and analyzed in terms of effective models. Furthermore, criteria for the applicability of approximate methods are derived and discussed. In this context, special focus is placed on the local density approximation, where fields are assumed to be locally homogeneous in space. Eventually, we apply our findings to the multiphoton regime. Special emphasis is on the importance of linear momentum conservation and the effect of its absence in momentum spectra within approximations based on local homogeneity of the fields.