Electromagnetic structure of the nucleon and the Roper resonance in a light-front quark approach

TL;DR

This paper employs a relativistic light-front quark model to analyze the electromagnetic structure of the nucleon and Roper resonance, providing insights into their form factors and internal composition at high momentum transfers.

Contribution

It introduces a mixed-state model for the Roper resonance combining three-quark and molecular components within a light-front framework.

Findings

The model accurately describes elastic and transition form factors up to high Q2.

Experimental data suggest the Roper resonance has a composite structure.

The approach extends understanding of nucleon and resonance internal dynamics.

Abstract

A relativistic light-front quark model is used to describe both the elastic nucleon and nucleon-Roper transition form factors in a large Q2 range, up to 35 GeV2 for the elastic and up to 12 GeV2 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, and show that existing experimental data are indicative of a composite structure of the Roper resonance.