Masses of ground and excited-state hadrons

TL;DR

This paper uses Dyson-Schwinger equations with a contact interaction to compute the spectrum of ground and excited light hadrons, providing insights into baryon structure and matching some experimental and model data.

Contribution

It presents the first unified Dyson-Schwinger equation calculation of both meson and baryon spectra, including excited states, within a symmetry-preserving contact interaction framework.

Findings

Computed baryon masses agree with dynamical coupled-channels models.

Achieved a 13% RMS-relative error per degree of freedom.

Provided insights into relationships between nucleon, Delta, and quark-diquark correlations.

Abstract

We present the first Dyson-Schwinger equation calculation of the light hadron spectrum that simultaneously correlates the masses of meson and baryon ground- and excited-states within a single framework. At the core of our analysis is a symmetry-preserving treatment of a vector-vector contact interaction. In comparison with relevant quantities the root-mean-square-relative-error/degree-of freedom is 13%. Notable amongst our results is agreement between the computed baryon masses and the bare masses employed in modern dynamical coupled-channels models of pion-nucleon reactions. Our analysis provides insight into numerous aspects of baryon structure; e.g., relationships between the nucleon and Delta masses and those of the dressed-quark and diquark correlations they contain.