A version of the Jost-Lehmann-Dyson representation is used to study the forward-spin-averaged "Compton" amplitude constructed from conserved currents. Bjorken's relationship between the divergence in electromagnetic mass shifts and the equal-time commutator of a current density and a time derivative of a current density is clarified and extended to include the case where subtractions in the amplitude are necessary. The connection between equal-time commutators and some features of the radiative corrections to β decay are discussed, and some properties of Schwinger terms are developed.
No takes yet. Share an insight, caveat, or question.
Cornwall et al. (1968) studied this question.
Synapse has enriched one closely related paper. Consider it for comparative context: