Testing Lorentz Invariance Violation with WMAP Five Year Data
  We consider different renormalizable models of Lorentz invariance violation. We show that the limits on birefringence of the propagation of cosmic microwave background photons from the five year data of the Wilkinson microwave anisotropy probe (WMAP) can be translated into a limit of Lorentz symmetry violation. The obtained limits on Lorentz invariance violation are stronger than other published limits. We also cast them in terms of limits on a birefringent effective photo "mass" and on a polarization dependence of the speed of light. 
Tina Kahniashvili, Ruth Durrer, and Yurii Maravin