Consistency of isotropic modified Maxwell theory: Microcausality and unitarity

TL;DR

This paper investigates the Lorentz-violating isotropic modified Maxwell theory, identifying parameter ranges where microcausality and unitarity are preserved, and extends analysis to anisotropic cases.

Contribution

It characterizes the parameter domain ensuring microcausality and unitarity in isotropic modified Maxwell theory and explores related anisotropic cases.

Findings

Identifies parameter ranges where microcausality holds.

Determines unitarity conditions for the theory.

Extends analysis to anisotropic nonbirefringent cases.

Abstract

The Lorentz-violating isotropic modified Maxwell theory minimally coupled to standard Dirac theory is characterized by a single real dimensionless parameter which is taken to vanish for the case of the standard (Lorentz-invariant) theory. A finite domain of positive and negative values of this Lorentz-violating parameter is determined, in which microcausality and unitarity hold. The main focus of this article is on isotropic modified Maxwell theory, but similar results for two anisotropic nonbirefringent cases are presented in the appendices.