Analytic parametrizations of the ${\gamma }^{\ast }N\to N(1440)$ form factors inspired by Light-Front holography

Abstract

We present analytic parametrizations for the ${\gamma }^{\ast }N\to N(1440)$ form factors derived from light-front holography in leading twist approximation. The new parametrizations describe the electromagnetic form factors using analytic functions dependent on the masses of the $\rho$ meson and respective radial excitations, as well as the masses of the nucleon and the resonance $N(1440)$. The free parameters of the model, associated with three independent couplings, are interpreted as bare couplings, and are fixed by the nucleon data for large $Q^2$. The proposed parametrizations compare remarkably well with the empirical data for $Q^2>2$ GeV${}^2$, corroborating the dominant role of the valence quark degrees of freedom in the ${\gamma }^{\ast }N\to N(1440)$ transition.

Comments: 7 pages, 4 figures. Extended version. Accepted for publication