Fitting of Electromagnetic Nucleon Form Factors in a Vector-Dominance Model

Abstract

By using the Lagrangian theory of vector dominance of Kroll, Lee, and Zumino, a four-parameter fit to the experimental data for the electromagnetic nucleon form factors for spacelike four-momentum transfer squared (${q}^{2}$) is obtained. The isovector, hypercharge, and baryon-number parts of the nucleon-vector-meson vertices are assumed to have phenomenologically ${(1+\frac{{q}^{2}}{{{\ensuremath{\Lambda}}_{I}}^{2}})}^{\ensuremath{-}1}$, ${(1+\frac{{q}^{2}}{{{\ensuremath{\Lambda}}_{Y}}^{2}})}^{\ensuremath{-}1}$, and ${(1+\frac{{q}^{2}}{{{\ensuremath{\Lambda}}_{N}}^{2}})}^{\ensuremath{-}1}$ momentum dependence. The slope of ${{G}_{E}}^{n}$ at ${q}^{2}=0$ is set equal to the Krohn-Ringo value of 0.457 ${(\frac{\mathrm{BeV}}{c})}^{\ensuremath{-}2}\ifmmode\pm\else\textpm\fi{}5%$. The result of the fitting is satisfactory for both large and small ${q}^{2}$.