# Radiative correction to the equivalent-photon spectrum of a relativistic electron and the two-photon process

Abstract

On the basis of the improved Weizsaecker-Williams equivalent-photon spectrum of a fast charged particle, we calculate the radiative correction to this spectrum. The calculation involves the virtual-photon radiative correction, the soft- and hard-bremsstrahlung contributions, and the vacuum-polarization contribution. The results are used to calculate the radiative correction to two-photon production of neutral bosons and pair production of charged fermions and bosons. General features are that the elastic vertex radiative corrections to these processes are negative and large, up to 10--20%, while the total radiative corrections, including emission of an extra hard photon, are on the other hand positive and in general considerably smaller, of the order of 1%. The effect of electron tagging on the radiative corrections is briefly discussed.