Trident pair production in strong laser pulses

TL;DR

This paper calculates the trident pair production amplitude in strong laser fields, considering finite pulse durations and analyzing the contributions of different processes while emphasizing gauge invariance and theoretical consistency.

Contribution

It introduces a nonperturbative approach to compute the trident process with finite laser pulses, clarifying the roles of one-step and two-step mechanisms and their gauge invariance.

Findings

Explicit separation of one-step and two-step contributions

Demonstration of gauge invariance in the amplitudes

Discussion of the relation to the optical theorem

Abstract

We calculate the trident pair production amplitude in a strong laser background. We allow for finite pulse duration, while still treating the laser fields nonperturbatively in strong-field QED. Our approach reveals explicitly the individual contributions of the one-step and two-step processes. We also expose the role gauge invariance plays in the amplitudes and discuss the relation between our results and the optical theorem.