CROSS-SECTION OF HIGH-ENERGY PHOTON SPLITTING IN THE ELECTRIC-FIELDS OF HEAVY-ATOMS

Various differential cross sections of high-energy photon splitting in the electric fields of heavy atoms are calculated exactly in the para meter Z alpha. The consideration is based on the quasiclassical approa ch applicable for small angles between all photon momenta. The express ions obtained are valid for arbitrary transverse momenta of final phot ons. The detailed investigation of the process is performed taking int o account the effect of screening. The exact cross section turns out t o be noticeably smaller than the result obtained in the Born approxima tion.