Valence quark contributions for the gamma N -> P11(1440) transition

TL;DR

This paper uses a covariant spectator quark model to estimate valence quark contributions to the gamma N -> P11(1440) transition form factors, aligning with experimental and lattice QCD data, and also assesses meson cloud effects.

Contribution

It applies a parameter-free covariant quark model to analyze the P11(1440) resonance transition form factors, integrating valence quark and meson cloud contributions.

Findings

Results agree with experimental data at high Q2.

Valence quark contributions dominate at high Q2.

Meson cloud effects are significant at lower Q2.

Abstract

A covariant spectator quark model is applied to estimate the valence quark contributions to the$ F1*(Q2) and F2*(Q2) transition form factors for the gamma N -> P11(1440) reaction. The Roper resonance, P11(1440), is assumed to be the first radial excitation of the nucleon. The model requires no extra parameters except for those already fixed by the previous studies for the nucleon. The results are consistent with the experimental data in the high Q2 region, and those from the lattice QCD. Finally the model is also applied to estimate the meson cloud contributions from the CLAS and MAID analysis.