A uniform locally constant field approximation for photon-seeded pair production

TL;DR

This paper develops an improved uniform locally constant field approximation (ULCFA) for photon-seeded pair production, enhancing accuracy in simulations of laser-particle interactions at moderate intensities.

Contribution

The paper introduces an extended ULCFA method that outperforms the standard LCFA in predicting pair creation rates at lower intensity parameters.

Findings

ULCFA matches exact analytical results for short pulses.

ULCFA remains accurate at smaller intensity parameters.

Benchmarking confirms improved performance over standard LCFA.

Abstract

A challenge to upcoming experiments that plan to collide a particle beam with laser pulses of moderate intensity is how to correctly incorporate quantum effects into simulation frameworks. Using a uniform approach, we extend the widely-used locally constant field approximation (LCFA) to derive an improved rate of photon-seeded pair creation (the nonlinear Breit-Wheeler process). By benchmarking our "ULCFA" expressions with the lightfront spectrum of: i) exact analytical results and ii) numerical integration of the QED probability for short pulses, we show that our extended approach remains accurate at smaller values of the intensity parameter than the standard LCFA.