The transitions gamma gamma -> nu bar nu and gamma -> gamma gamma in a   strong magnetic field
  The photon-neutrino process gamma gamma -> nu bar nu and photon splitting are considered in a strong magnetic field. The partial polarization amplitudes are calculated within the standard model in the limit of a strong field. The amplitudes do not depend on the field strength in this limit. Using the vector parts of the amplitudes, the process of the photon splitting gamma -> gamma gamma is investigated both below and above the pair creation threshold. The splitting probabilities are calculated taking account of the photon dispersion and large radiative corrections near the resonance. 
M.V. Chistyakov, A.V. Kuznetsov, N.V. Mikheev