Breit-Wheeler process in very short electromagnetic pulses

TL;DR

This paper investigates the Breit-Wheeler process in short laser pulses, revealing how pulse shape and non-linear dynamics influence electron-positron pair production, with implications for experimental and theoretical studies.

Contribution

It provides a detailed analysis of how short pulse duration and non-linear effects impact pair production, offering practical formulas for different regimes.

Findings

Short pulses can significantly enhance pair production probability.

Pulse shape and duration effects are crucial in the weak-field regime.

Non-linear dynamics dominate at high field intensities.

Abstract

The generalized Breit-Wheeler process, i.e. the emission of $e^+e^-$ pairs off a probe photon propagating through a polarized short-pulsed electromagnetic (e.g.\ laser) wave field, is analyzed. We show that the production probability is determined by the interplay of two dynamical effects. The first one is related to the shape and duration of the pulse and the second one is the non-linear dynamics of the interaction of $e^\pm$ with the strong electromagnetic field. The first effect manifests itself most clearly in the weak-field regime, where the small field intensity is compensated by the rapid variation of the electromagnetic field in a limited space-time region, which intensifies the few-photon events and can enhance the production probability by orders of magnitude compared to an infinitely long pulse. Therefore, short pulses may be considered as a powerful amplifier. The non-linear dynamics in the multi-photon Breit-Wheeler regime plays a decisive role at large field intensities, where effects of the pulse shape and duration are less important. In the transition regime, both effects must be taken into account simultaneously. We provide suitable expressions for the $e^+e^-$ production probability for kinematic regions which can be used in transport codes.