Nucleon Form Factors in the Helicity Representation

Abstract

The cross section for electron-nucleon scattering should be expressed in terms of form factors which are proportional to helicity amplitudes. Then electron-nucleon scattering and pion-nucleon scattering are related even more closely by the pi - pi interaction in I = 1, J = 1. In particular the S-wave charge-exchange scattering data complement data on the electric isovector form factor. A consistent picture of the I = 1, J = 1 pi - pi interaction requires the narrowness of the 750-Mev resonance. (auth)