On Duality Invariant Yang-Mills Theory

We provide an explicit construction of a manifestly duality invariant, interacting deformation of Maxwell theory in four dimensions in terms of mutually local, but interacting 1- and 3-forms. Interestingly, our theory is formulated directly as a BRST quantized gauge theory, while the underlying gauge invariant Lagrangian before gauge fixing is obscured. Furthermore, the underlying gauge invariance is based on an associative, rather than a Lie symmetry.