Worldline Instantons and Pair Production in Inhomogeneous Fields

TL;DR

This paper introduces a semiclassical method using worldline instantons to compute pair production rates in inhomogeneous electric fields within quantum electrodynamics, accounting for both scalar and spinor cases.

Contribution

It develops a novel semiclassical approach with worldline instantons for nonperturbative pair production calculations in inhomogeneous fields, extending to spinor QED.

Findings

Temporal inhomogeneities enhance pair production.

Spatial inhomogeneities suppress pair production.

The method applies to both scalar and spinor QED.

Abstract

We show how to do semiclassical nonperturbative computations within the worldline approach to quantum field theory using ``worldline instantons''. These worldline instantons are classical solutions to the Euclidean worldline loop equations of motion, and are closed spacetime loops parametrized by the proper-time. Specifically, we compute the imaginary part of the one loop effective action in scalar QED using ``worldline instantons'', for a wide class of inhomogeneous electric field backgrounds. We treat both time dependent and space dependent electric fields, and note that temporal inhomogeneities tend to shrink the instanton loops, while spatial inhomogeneities tend to expand them. This corresponds to temporal inhomogeneities tending to enhance local pair production, with spatial inhomogeneities tending to suppress local pair production. We also show how the worldline instanton technique extends to spinor QED.