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

Understand

In a previous article [arXiv:1011.4258], we established the consistency of isotropic modified Maxwell theory for a finite range of the Lorentz-violating parameter \tilde{kappa}_{tr}, which includes both positive and negative values of \tilde{kappa}_{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 \tilde{kappa}_{tr} (corresponding to a "slow" photon).
• Here, we present a related model which gives rise to isotropic modified Maxwell theory with a negative parameter \tilde{kappa}_{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.