High-energy expansion of Coulomb corrections to the e+e- photoproduction cross section -: art. no. 022708

The correction of order 1/omega to the high-energy total e(+)e(-) photoproduction cross section in the electric field of a heavy atom is derived with the exact account of this field; omega is the photon energy. The consideration is based on the use of the quasiclassical electron Green's function in an external electric field. The next-to-leading correction to the cross section is discussed. The influence of screening on the Coulomb corrections is examined in the leading approximation. It turns out that the corresponding correction to the high-energy total cross section is omega independent. In the region where both produced particles are relativistic, the corrections to the high-energy asymptotics of the electron (positron) spectrum are derived. Our results for the total cross section are in good agreement with experimental data for photon energies down to a few MeV. In addition, the corrections to the bremsstrahlung spectrum are obtained from the corresponding results for pair production.