Resurgence of the Effective Action in Inhomogeneous Fields

TL;DR

This paper explores how inhomogeneous background fields alter the non-perturbative structure of the effective action, revealing new effects and demonstrating resurgent methods for accurate analytic continuation.

Contribution

It introduces the impact of inhomogeneities on the effective action's non-perturbative structure and applies resurgent extrapolation techniques for better predictions.

Findings

Inhomogeneities turn simple Borel poles into branch points.

Resurgent methods enable accurate weak-to-strong field extrapolations.

Extrapolations outperform standard WKB and local approximations.

Abstract

We show how background field inhomogeneities modify the non-perturbative structure of the effective action. The simple Borel poles of the Euler-Heisenberg effective action become branch points, and new branch points also appear, indicating new non-perturbative effects. This information is resurgently encoded in the perturbative weak field expansion, and becomes physically significant for strongly inhomogeneous fields. We also show that resurgent extrapolation methods permit the decoding of a surprising amount of non-perturbative information from a relatively modest amount of perturbative input, enabling accurate analytic continuations from weak field to strong field, and of a spatially dependent magnetic background to a time dependent electric background. These extrapolations are far superior to standard WKB and locally constant field approximations.