An eikonal expansion in quantum electrodynamics

The classical limit of quantum electrodynamics is studied using functional methods. Two-point Green functions are developed in power series of sigmasup(μγ)Fsub(μγ). In particular nth order spin corrections are associated to terms coming from (sigma F)sup(n). The first order spin correction is analyzed in detail. In the limit of zero photon mass it exhibits cuts, in the complex energy plane, whose effects are mainly concentrated on the branching points, with coefficients (log μ)-1. (Auth.)