Electromagnetic Properties of the Nucleon in a Finite Source Theory

Abstract

Some electromagnetic properties of nucleons are investigated under the assumption that the nucleon consists of a spin one-half core particle in interaction with the pion field through a gauge-invariant, non-relativistic, pseudoscalar, finite source interaction. Recoil of the nucleon core is neglected and the weak coupling approximation is used. A method is presented for making the finite source interaction between two particle fields gauge-invariant by introducing filaments of current in the region of the source function. The theoretical contributions of interaction currents to the magnetic moments of the proton and neutron are calculated and found to be small compared to the observed anomalous moments and of the opposite sign. The model is used to calculate, in the limit of zero source size, the total and differential cross sections for scattering of gamma rays from nucleons. The results, which are presented graphically, are found to be in accord with the conditions imposed on a finite theory in the preceding paper. They are compared to the results obtained by Sachs and Foldy on the basis of a point-source theory.