  We consider QED in a constant axial vector background (\AE ther). Further
Lorentz invariance violations (LIV) might occur owing to radiative corrections.
The phenomenology of this model is studied, clarifying issues related to the
various regularizations employed, with a particular emphasis on the induced
photon mass. To this concern, it is shown that in the presence of LIV
dimensional regularization may produce a radiatively induced finite photon
mass. The possible physical role of the large momentum cutoff is elucidated and
the finite temperature radiative corrections are evaluated. Finally, various
experimental bounds on the parameters of the model are discussed.
