New treatment of the bound-state problem in quantum field theory

A new formalism for the description of the two-body system and well suited to the bound-state problem is developed within the context of quantum electrodynamics. The resulting two-body equation is a two-time, covariant, functional-differential one which, in the center-of-mass frame, reduces to a single-time, Schrödingertype equation. Application of this equation is illustrated by calculating several known recoil and structure corrections to the energy levels of positronium and hydrogen. Further extensions and applications of the formalism are discussed.