Nucleon Resonance Electrocouplings from Light-Front Quark Models at $${\varvec{Q}}^2 $$ Q 2 up to 12 $$\hbox {GeV}^2$$ GeV 2

Abstract

A relativistic light-front quark model is used to describe both the elastic nucleon and nucleon-Roper transition form factors in a large \(Q^2\) range, up to 35 \(\hbox {GeV}^2\) for the elastic and up to 12 \(\hbox {GeV}^2\) for the resonance case. Relativistic three-quark configurations satisfying the Pauli exclusion principle on the light-front are used for the derivation of the current matrix elements. The Roper resonance is considered as a mixed state of a three-quark core configuration and a molecular \(N+\sigma \) hadron component. Based on this ansatz we obtain a realistic description of both processes, elastic and inelastic, in the sector of positive parity and show that existing experimental data are indicative of a composite structure of the Roper resonance. A useful generalization of this technique is suggested for description of negative parity nucleon resonances \(1/2^-,\,3/2^-,\,5/2^-\).