Schwinger pair production in counterpropagating laser pulses: Identifying volume factors

TL;DR

This paper develops a method to accurately estimate vacuum pair production in complex laser pulse configurations by applying volume factors to simplified models, enabling quick predictions with about 10% uncertainty.

Contribution

It introduces universal volume factors for predicting pair production yields in realistic laser setups based on simplified models, validated within the locally-constant field approximation.

Findings

Derived closed-form expressions for volume factors

Achieved 10% accuracy in connecting simplified and full models

Provided practical formulas for estimating pair yields in experiments

Abstract

We investigate the nonperturbative process of vacuum pair production in a combination of two counterpropagating linearly polarized laser pulses of a finite spatial extent. By means of the locally-constant field approximation (LCFA), we calculate the total particle yield for the corresponding four-dimensional setup and compare it with the estimates obtained for simplified low-dimensional scenarios. Within the domain where the LCFA is well justified, we examine a combination of two plane-wave pulses, a standing electromagnetic wave, and a spatially uniform oscillating field and demonstrate that at each of these three levels of approximation, one can accurately predict the actual particle number by multiplying the results by properly chosen volume factors depending on the field parameters. We present closed-form expressions for these factors providing universal prescriptions for evaluating the particle yield. Our final formula connecting the spatially uniform setup with the four-dimensional scenario has a relative uncertainty of the level of $10\%$. The explicit correspondences deduced in this study not only prove the relevance of the approximate predictions, but also allow one to quickly estimate the number of pairs for various realistic scenarios without performing multidimensional LCFA integrations.