Phenomenological Analysis of theγNN*Form Factors

Abstract

The data on electroexcitation of $N^{*}$ in the momentum-transfer range $-q^2=0.1-2.33\mathrm{}$ Ge${\mathrm{V}}^2$ have been analyzed phenomenologically, using an isobar model. Assuming only the $M1\mathrm{}$ transition, we obtained a phenomenological form factor for the $\gamma N{N}^{*}$ vertex. This form factor is found to decrease much faster than the elastic nucleon form factors. This implies that the $N^{*}$ has a larger spatial extension than the $N$.