On photon splitting in theories with Lorentz invariance violation
  In a model with Lorentz invariance violation implemented through modified dispersion relations, we estimate the rate for the decay process gamma -> 3 gamma and find that it provides a relevant bound on Lorentz invariance violation. 
Graciela Gelmini (UCLA), Shmuel Nussinov (Tel Aviv U.), Carlos E.   Yaguna (UCLA)