The second-order electromagnetic contribution to the mass of a hadron needs an ultraviolet-divergent renormalization. An explicitly renormalized Cottingham formula is derived, and the renormalization is related to the counterterms obtained in perturbation theory. The main effect is to impose a cut-off Λ equal to the subtraction mass used in the renormalization. Within quantum chromodynamics it is shown that the Λ-dependence of the Cottingham formula for the neutron-proton mass difference is of the same magnitude as fourth-order electromagnetic corrections.
All Science Journal Classification (ASJC) codes
- Nuclear and High Energy Physics