Transition form factors and helicity amplitudes for electroexcitation of negative- and positive parity nucleon resonances in a light-front quark model

TL;DR

This paper develops a light-front quark model with specific quark configurations to describe high-$Q^2$ transition form factors and helicity amplitudes for nucleon resonances, fitting CLAS data and estimating quark core contributions.

Contribution

It introduces a basis of quark configurations at light front for modeling nucleon resonance electroproduction, including configuration mixing and hadron-molecular states.

Findings

Successfully describes high-$Q^2$ data for $N_{1/2^-}(1535)$ and $N_{1/2^+}(1440)$

Estimates the quark core contribution in resonance wave functions

Provides a framework for analyzing resonance structure at high momentum transfer

Abstract

A workable basis of quark configurations $s^3$, $s^2p$ and $sp^2$ at light front has been constructed to describe the high-$Q^2$ behavior of transition form factors and helicity amplitudes in the electroproduction of the lightest nucleon resonances, $N_{1/2^-}(1535)$ and $N_{1/2^+}(1440)$. High-quality data of the CLAS Collaboration are described in the framework of a model which takes into account mixing of the quark configurations and the hadron-molecular states. The model allows for a rough estimate of the quark core weight in the wave function of the resonance in a comparison with high momentum transfer data on resonance electroproduction.