Electromagnetic Structure of the Nucleon. I†

The electromagnetic structure of the nucleon is investigated in detail. As for its isovector part, the distribution functions of charge and anomalous magnetic moment are obtained with use of two different methods, the second order relativistic perturbation and the static approximation, and the S-wave and recoil effects and higher order corrections are examined by comparing these results. The meson structure correction in the fourth order perturbation is also calculated, and it is shown that its contribution is rather small. As for the isoscalar part, the 3π-state contribution is calculated by the lowest order perturbation (order g6), and its rough numerical evaluation is carried out. The result obtained is favorable for explaining the recent experimental results (but not conclusive). Hyperon closed loop effects are also discussed.