Electromagnetic fields with vanishing quantum corrections

TL;DR

This paper demonstrates that a broad class of null electromagnetic fields remain exact solutions even when Maxwell's equations are modified with arbitrary nonlinear and higher-derivative terms, applicable in various spacetime backgrounds.

Contribution

It proves that null electromagnetic fields are immune to a wide range of generalized electrodynamics modifications, including non-linear and higher-derivative theories, in diverse spacetime geometries.

Findings

Null electromagnetic fields are solutions to generalized electrodynamics.

Immunity holds in flat, (anti-)de Sitter, and certain Kundt spacetimes.

Results apply to theories motivated by QED and string theory.

Abstract

We show that a large class of null electromagnetic fields are immune to any modifications of Maxwell's equations in the form of arbitrary powers and derivatives of the field strength. These are thus exact solutions to virtually any generalized classical electrodynamics containing both non-linear terms and higher derivatives, including, e.g., non-linear electrodynamics as well as QED- and string-motivated effective theories. This result holds not only in a flat or (anti-)de Sitter background, but also in a larger subset of Kundt spacetimes, which allow for the presence of aligned gravitational waves and pure radiation.