Classical Resummation and Breakdown of Strong-Field QED

QED perturbation theory has been conjectured to break down in sufficiently strong backgrounds, obstructing the analysis of strong-field physics. We show that the breakdown occurs even in classical electrodynamics, at lower field strengths than previously considered, and that it may be cured by resummation. As a consequence, an analogous resummation is required in QED. A detailed investigation shows, for a range of observables, that unitarity removes diagrams previously believed to be responsible for the breakdown of QED perturbation theory.

Automated summary

The breakdown of QED perturbation theory has been observed in classical electrodynamics at lower field strengths than previously considered, suggesting the need for resummation in both classical and quantum scenarios. Detailed investigation has shown that unitarity removes diagrams previously believed to be responsible for the breakdown of QED perturbation theory, indicating a potential solution to this issue.