Models for low-energy Lorentz violation in the photon sector: Addendum to ‘Consistency of isotropic modified Maxwell theory’

In a previous article, Klinkhamer and Schreck (2011) [1], we established the consistency of isotropic modified Maxwell theory for a finite range of the Lorentz-violating parameter κ˜tr, which includes both positive and negative values of κ˜tr. As an aside, we mentioned the existence of a physical model which, for low-energy photons, gives rise to isotropic modified Maxwell theory with a positive parameter κ˜tr (corresponding to a “slow” photon). Here, we present a related model which gives rise to isotropic modified Maxwell theory with a negative parameter κ˜tr (corresponding to a “fast” photon). Both models have an identical particle content, photon and Dirac particles, but differ in the type of spacetime manifold considered.