Electromagnetic interactions of nucleons in nuclei

Off-shell ambiguities in the nucleon current are discussed in the framework of the impulse approximation and of the vector-scalar model. For the former it is shown that, without careful consideration of the consequences of current conservation, one can easily obtain unphysical results (infinite cross sections). In the latter very large variations in the electron scattering cross section, depending on the choice of the operator for the anomalous magnetic moment, are found