Breit-Wheeler Process in Intense Short Laser Pulses

TL;DR

This paper investigates electron-positron pair creation in intense short laser pulses, analyzing energy-angular distributions, polarization effects, and phase control, with a focus on the nonperturbative regime and pulse duration impacts.

Contribution

It provides a detailed analysis of pair creation in finite laser pulses, comparing exact and approximate models, and explores polarization and phase effects on pair production yields.

Findings

Good agreement between models for long pulses

Pair creation depends on laser pulse polarization

Carrier-envelope phase influences angular distributions

Abstract

Energy-angular distributions of electron-positron pair creation in collisions of a laser beam and a nonlaser photon are calculated using the $S$-matrix formalism. The laser field is modeled as a finite pulse, similar to the formulation introduced in our recent paper in the context of Compton scattering [Phys. Rev. A {\bf 85}, 062102 (2012)]. The nonperturbative regime of pair creation is considered here. The energy spectra of created particles are compared with the corresponding spectra obtained using the modulated plane wave approximation for the driving laser field. A very good agreement in these two cases is observed, provided that the laser pulse is sufficiently long. For short pulse durations, this agreement breaks down. The sensitivity of pair production to the polarization of a driving pulse is also investigated. We show that in the nonperturbative regime, the pair creation yields depend on the polarization of the pulse, reaching their maximal values for the linear polarization. Therefore, we focus on this case. Specifically, we analyze the dependence of pair creation on the relative configuration of linear polarizations of the laser pulse and the nonlaser photon. Lastly, we investigate the carrier-envelope phase effect on angular distributions of created particles, suggesting the possibility of phase control in relation to the pair creation processes.