Renormalization and analysis of the Cottingham formula and the consistency of SU(3) and electromagnetic mass shifts in parton models

We show that the divergent pieces of the Cottingham expression for electromagnetic mass shifts may always be identified, by means of structure-function sum rules, with the contributions (to the total mass shift) resulting from the divergent electromagnetic mass shifts and propagator renormalization of the bare partons themselves. This enables one to carry out a renormalization program, to first order in α. The SU(3) and electromagnetic mass shifts of the baryon octet are analyzed and shown to display a substantial consistency with one another. Predictions for fixed poles in the Compton amplitudes of all baryons result once that for the proton is known. In addition we extract quark masses for a given value of the π-N σ term.