PHOTON SPLITTING ABOVE THE PAIR CREATION THRESHOLD IN A STRONG MAGNETIC-FIELD

The process of photon splitting gamma-->gamma gamma in a strong magnet ic field is investigated both below and above the pair creation thresh old. Contrary to the statement by Paler et al., the ''allowed'' channe l gamma(parallel to)-->gamma(perpendicular to)gamma(perpendicular to) is shown not to be a comprehensive description of splitting in the str ong field because the ''forbidden'' channel y(parallel to)-->gamma(par allel to)gamma(perpendicular to) is also essential. The partial amplit udes and the splitting probabilities are calculated taking account of the photon dispersion and large radiative corrections near the resonan ce. (C) 1998 Published by Elsevier Science B.V. All rights reserved.