We examine the radiative corrections to an extension of the standard model containing a Lorentz-violating axial vector parameter. At second order in this parameter, the photon self-energy is known to contain terms that violate gauge invariance. Previously, this has been treated as a pathology, but it is also possible to take the gauge noninvariant terms at face value. These terms then make Lorentz-violating contributions to the photon mass, and directly measured limits on the photon mass can be used to set bounds on the Lorentz violation at better than the ${10}^{-22}\mathrm{GeV}$ level.

• Received 3 January 2006

DOI:https://doi.org/10.1103/PhysRevD.73.036005