Bound state quantum electrodynamics with polarization sources

Abstract

A manifestly gauge invariant relativistic quantum field theory of the interaction of atomic systems with electromagnetic fields is shown to be systematically obtained from conventional quantum electrodynamics. The basic ingredient is an exact decomposition of the Dirac sources J μ modified to include the binding, into polarization sources P and M . The transformation of the conventional theory is achieved by means of a generalized Power-Zienau-Woolley transformation. While J μ couple to the potentials A μ , the polarization sources are shown to couple directly to the field intensities E and B . An explicit separation between electric and magnetic interactions is thus obtained which is in close correspondence w'ith the case in the semi-classical radiation theory. The relevance of the transformed theory to problems involving intense electromagnetic fields is pointed out and discussed.