Radiative Corrections in Strong Fields

Abstract

Radiative corrections in a strong static external field can be calculated to all orders in the external field by working in the Furry bound-interaction picture. The self-energy correction in a Coulomb field has been calculated for all n=1 or 2 states for a wide range of values of the nuclear charge Z. In the Wichmann-Kroll approach, the bound-electron propagation function is expanded in angular momentum eigenfunctions. Some aspects of this method as applied to the self-energy calculation, including mass renormalization and numerical methods, are discussed here. The Coulomb field self-energy correction gives the main contribution to the Lamb shift in high-Z hydrogenlike atoms. In high-Z few-electron atoms, energy levels can be calculated by applying perturbation theory where, in lowest order, the electrons are treated as non-interacting Dirac particles. Electron-electron interactions and radiative corrections are then calculated as perturbations. In this framework, the Coulomb-field radiative corrections give the leading radiative corrections for the few-electron system. Comparison to experiment is made for one- and two-electron atoms.