ABSTRACT
The divergence occurs from high frequencies and at first it was thought the hadrons might be soft at high frequency and the electromagnetic self energy convergent. Electromagnetic mass shifts come from the emission and reabsorption of a virtual photon. The interaction must depend on the mutual spin relation of the pair. This chapter discusses the forward scattering in more detail including spin effects. The particles should act exactly as if they were point particles. One can compute the effect semiclassically or from the non-relativistic approximation to the Schroedinger equation with spin or again by diagrams assuming a pure particle with no internal excited states.
