Magnetic moments and electromagnetic radii of nucleon and $\Delta (1232)$ in an extended GBE model

Abstract

We derive the exchange currents of pseudoscalar, vector, and scalar mesons from Feynman diagrams, and use them to calculate the magnetic form factors of nucleon and $\Delta (1232)$. The magnetic moments and electromagnetic radii are obtained by using those form factors and the parameters determined from the masses of nucleon and $\Delta (1232)$. We find the magnetic moments and electromagnetic radii of nucleon and $\Delta (1232)$ can be produced very well in the extended Goldstone-boson-exchange model (GBE) in which all of pseudoscalar, vector and scalar meson nonet are included. The magnetic moments of $\Delta (1232)$ are closer to experiment values and results from lattice calculation than the results obtained by the model without other mesons except for pion and sigma.

Comments: 15 pages,5 figures