Electromagnetic form Factors and Radii of the Nucleon in the Extended Vector Meson Dominance Model

Abstract

An extended vector meson dominance model is proposed for describing electromagnetic nucleon form factors. The model incorporates families of \(\rho\)- and \(\omega\)-mesons, including their excitations. Free parameters are determined through a global fit to experimental data for both space- and timelike momentum transfers. Meson masses and widths are set to empirical values, while residues at the poles of the ground-state \(\rho\)- and \(\omega\)-mesons align with findings from Frazer–Fulco unitarity relations and Bonn potential. The model adheres to constraints such as quark counting rules, the Okubo–Zweig–Iizuka rule, scaling relations for Sachs form factor at low and moderate momentum transfers, and suppression of Sachs form factors at the nucleon–antinucleon threshold. A good description is obtained for electromagnetic nucleon form factors across the experimentally accessible momentum range, as well as for the electric and magnetic radii, and Zemach radii of the nucleon.