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

In a previous article, Klinkhamer and Schreck (2011) , we established the consistency of isotropic modified Maxwell theory for a finite range of the Lorentz-violating parameter image, which includes both positive and negative values of image. 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 image (corresponding to a “slow” photon). Here, we present a related model which gives rise to isotropic modified Maxwell theory with a negative parameter image (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.