  In this work the Feynman-Schwinger representation for the two-body Greens
function is studied. After having given a brief introduction to the formalism,
we report on the first calculations based on this formalism. In order to
demonstrate the validity of the method, we consider the static case where the
mass of one of the particles becomes very large. We show that the heavy
particle follows a classical trajectory and we find a good agreement with the
Klein-Gordon result.
