Valence quark contributions for the γN → P₁₁(1440) form factors

Abstract

Using a covariant spectator quark model we estimate valence quark contributions to the F1*(Q²) and F2*(Q²) transition form factors for the γN→P11(1440) reaction. The Roper resonance, P11(1440), is assumed to be the first radial excitation of the nucleon. The present model requires no extra parameters except for those already fixed by previous studies of the nucleon. Our results are consistent with the experimental data in the high Q² region, and those from lattice QCD. We also estimate the meson cloud contributions, focusing on the low Q² region, where they are expected to be dominant.