Electroproduction of the $N^\ast(1535)$ nucleon resonance in QCD

TL;DR

This paper develops a QCD-based theoretical framework using light-cone sum rules to interpret upcoming high-Q^2 electroproduction data of the N*(1535) resonance, linking form factors to nucleon wave functions and lattice QCD results.

Contribution

It introduces a next-to-leading order calculation of N*(1535) form factors within a light-cone sum rule approach, connecting experimental data with nucleon distribution amplitudes and lattice QCD.

Findings

Form factors are dominated by twist-four distribution amplitudes.

Distribution amplitudes relate to P-wave three-quark wave functions.

Results are consistent with existing experimental data.

Abstract

Following the 12 GeV upgrade, a dedicated experiment is planned with the Hall B CLAS12 detector at Jefferson Lab, with the aim to study electroproduction of nucleon resonances at high photon virtualities up to $Q^2 = 12$ GeV$^2$. In this work we present a QCD-based approach to the theoretical interpretation of these upcoming results in the framework of light-cone sum rules that combine perturbative calculations with dispersion relations and duality. The form factors are thus expressed in terms of $N^\ast(1535)$ light-front wave functions at small transverse separations, called distribution amplitudes. The distribution amplitudes can therefore be determined from the comparison with the experimental data on form factors and compared to the results of lattice QCD simulations. The results of the corresponding next-to-leading order calculation are presented and compared with the existing data. We find that the form factors are dominated by the twist-four distribution amplitudes that are related to the $P$-wave three-quark wave functions of the $N^\ast(1535)$, i.e. to contributions of orbital angular momentum.