Influence of a medium on coherent scattering of high-energy photon

Abstract

The coherent scattering of photon in the Coulomb field (the Delbrück scattering) is considered for the momentum transfer $\Delta \ll m$ in the frame of the quasiclassical operator method. In high-energy region this process occurs over rather long distance. The process amplitude is calculated taking into account the multiple scattering of particles of the intermediate electron-positron pair in a medium. The result is the suppression of the process.

Comments: 6 pages, 1 Postscript figure, talk given at the International Conference "Quantization, Gauge Theory and Strings" dedicated to memory of Professor E.S.Fradkin, Moscow, June 5-10, 2000