Good and bad diquark properties and spatial correlations in lattice QCD

TL;DR

This paper investigates diquark properties in lattice QCD, confirming that only good diquarks exhibit attractive correlations and spherical shapes, supporting their role in modeling low-lying baryons.

Contribution

It provides the first lattice QCD analysis of diquark spectral masses and spatial correlations, validating the use of good diquarks as effective degrees of freedom in baryon models.

Findings

Good diquarks have attractive spatial correlations.

Only good diquarks are spherical with size ~0.6 fm.

Spectral masses agree with phenomenological expectations.

Abstract

We study good, bad and not-even-bad diquarks on the lattice in a gauge-invariant formalism in full QCD. We establish their spectral masses with short extrapolations to the physical point, observing agreement with phenomenological expectations. We find that only the good diquark has attractive quark-quark spatial correlations, with spherical shape and size $\sim0.6$ fm. Our results provide quantitative support for modelling the low-lying baryon spectrum using good light diquark effective degrees of freedom.