Virtual and Thermal Schwinger Processes

TL;DR

This paper explores how electric flux dissipation occurs via worldline instantons and parametric resonance, providing semiclassical rate calculations and discussing implications for axion fields and the weak gravity conjecture.

Contribution

It introduces a novel effective field theory description of flux dissipation without real charged pair creation in compact dimensions.

Findings

Flux dissipation can occur through scalar quanta production, not just pair creation.

Semiclassical calculations of dissipation rates are provided.

Implications for axion field range bounds are discussed.

Abstract

Electric flux may be screened by pair nucleation of heavy charges, a process that has a simple description in terms of a worldline instanton. When flux is wrapped around a small compact spatial dimension, worldline instantons still induce flux dissipation, but the leading process does not create real charged pairs. Instead, dissipation can be described in effective field theory as the production of long-wavelength scalar quanta via parametric resonance. The rate is computed semiclassically, and comments are made on the related problem of pair creation at finite temperature, for which differing results appear in the literature. Flux dissipation and the weak gravity conjecture together imply that the proper distance in field space a homogeneous axion field can traverse is bounded.