Low-lying fermion modes, topology and light hadrons in quenched QCD

TL;DR

This study investigates low-lying fermion eigenmodes in quenched lattice QCD using an overlap action, revealing their localization and correlation with instantons, and their role in reproducing hadron correlators.

Contribution

It demonstrates the localization of low eigenmodes and their correlation with instantons, supporting instanton liquid models in quenched QCD.

Findings

Chiral zero modes are localized and correlate with instantons.

Nonchiral modes also localize and correlate with instanton charges.

Restricted propagator correlators reproduce hadron correlators at small quark mass.

Abstract

We explore the properties of low lying eigenmodes of fermions in the quenched approximation of lattice QCD. The fermion action is a recently proposed overlap action and has exact chiral symmetry. We find that chiral zero-eigenvalue modes are localized in space and their positions correlate strongly with the locations (as defined through the density of pure gauge observables) of instantons of the appropriate charge. Nonchiral modes are also localized with peaks which are strongly correlated with the positions of both charges of instantons. These correlations slowly die away as the fermion eigenvalue rises. Correlators made of quark propagators restricted to these modes closely reproduce ordinary hadron correlators at small quark mass in many channels. Our results are in qualitative agreement with the expectations of instanton liquid models.