Photon Splitting in a Very Strong Magnetic Field
  Photon splitting in a very strong magnetic field is analyzed for energy $\omega < 2m$. The amplitude obtained on the base of operator-diagram technique is used. It is shown that in a magnetic field much higher than critical one the splitting amplitude is independent on the field. Our calculation is in a good agreement with previous results of Adler and in a strong contradiction with recent paper of Mentzel et al. 
V. N. Baier, A. I. Milstein and R. Zh. Shaisultanov