Photon splitting γ→νν̄ in an external magnetic field

The process of the photon splitting into the neutrino-antineutrino pair in a magnetic field is investigated. The amplitude and the probability are analysed in the limits of relatively small and strong fields. The probability is suppressed by a factor (GFme2)2 as compared with the probability of the pure electromagnetic process γ→e−e+. However, the process with neutrinos could play a role of an additional channel of stellar energy-loss.