Nonlinear electrodynamics with the maximum allowable symmetries

Abstract

Recently Bandos, Lechner, Sorokin, and Townsend [arXiv:2007.09092] have discovered that Maxwell's electrodynamics can be generalized so that the resulting nonlinear theory preserves both conformal invariance and SO(2) duality-rotation invariance. Their result can be derived in a simpler way.