Electromagnetic Structure of the Nucleon

Spectral representations of the electromagnetic form factors of the nucleon for fixed momentum transfer are proved as a function of the square of the four-momentum of the nucleon, based on the general principles of the quantum field theory and, using these representations, two sets of coupled equations for charge and magnetic moment form factors are derived. These equations are solved in an approximation in which only the lowest mass configuration is taken into account which consists of one pion and one nucleon. It is shown that the absorptive parts in this approximation are expressed in terms of the real pion production by virtual photon for I</it> = J</it> = ½ state and pion-nucleon vertex part, from which follows that (3-3) resonant state does not contribute to the form factors as far as the lowest mass configuration is concerned. Inclusion of (3-3) resonance and the second and third resonance requires the calculation of two pions and one nucleon state which is not attempted here.