# Perturbative methods for assisted nonperturbative pair production

## TL;DR

This paper develops perturbative and semiclassical methods to analyze the dynamically assisted Schwinger mechanism, enabling calculation of higher-order contributions and extending the approach to doubly assisted pair production.

## Contribution

It introduces new techniques for calculating higher-order effects and prefactors in assisted pair production, advancing understanding beyond previous perturbative treatments.

## Key findings

- Higher-order terms can significantly influence pair production rates.
- The worldline formalism provides an independent derivation of the momentum spectrum.
- Methods are applicable to doubly assisted pair production.

## Abstract

In the dynamically assisted Schwinger mechanism, the pair production probability is significantly enhanced by including a weak, rapidly varying field in addition to a strong, slowly varying field. In a previous paper we showed that several features of dynamical assistance can be understood by a perturbative treatment of the weak field. Here we show how to calculate the prefactors of the higher-orders terms, which is important because the dominant contribution can come from higher orders. We give a new and independent derivation of the momentum spectrum using the worldline formalism, and extend our WKB approach to calculate the amplitude to higher orders. We show that these methods are also applicable to doubly assisted pair production.