Effect of recentRpandRnmeasurements on extended Gari-Krümpelmann model fits to nucleon electromagnetic form factors

The Gari-Krümpelmann (GK) models of nucleon electromagnetic form factors, in which the $\rho ,$ $\omega ,$ and $\phi$ vector meson pole contributions evolve at high momentum transfer to conform to the predictions of perturbative QCD, was recently extended to include the width of the $\rho$ meson by substituting the result of dispersion relations for the pole and the addition of the ${\rho }^{\prime }$ (1450) isovector vector meson pole. This extended model was shown to produce a good overall fit to all the available nucleon electromagnetic form-factor data. Since then new polarization data shows that the electric to magnetic ratios $R_p$ and $R_n$ obtained are not consistent with the older $G_{\mathrm{Ep}}$ and $G_{\mathrm{En}}$ data in their range of momentum transfer. The model is further extended to include the ${\omega }^{\prime }$ (1419) isoscalar vector meson pole. It is found that while this GKex cannot simultaneously fit the new $R_p$ and the old $G_{\mathrm{En}}$ data, it can fit the new $R_p$ and $R_n$ well simultaneously. An excellent fit to all the remaining data is obtained when the inconsistent $G_{\mathrm{Ep}}$ and $G_{\mathrm{En}}$ is omitted. The model predictions are extended beyond the data, if needed, to momentum transfer squared, $Q^2,$ of $8{\mathrm{GeV}}^2{/c}^2.$