Vacuum structure revealed by over-improved stout-link smearing compared with the overlap analysis for quenched QCD

TL;DR

This study compares the topological structures of quenched QCD revealed by over-improved stout-link smearing and overlap fermion analysis, highlighting their similarities and relations to zero modes and non-zero modes.

Contribution

It provides a detailed comparison between gluonic and fermionic topological density methods in quenched QCD, establishing their correspondence and cluster structure similarities.

Findings

Similar cluster structures for moderate smearing and specific cutoff ranges.

Relation between gluonic topological density and overlap zero modes.

Matching of densities via two-point functions and point-by-point fitting.

Abstract

A detailed comparison is made between the topological structure of quenched QCD as revealed by the recently proposed over-improved stout-link smearing in conjunction with an improved gluonic definition of the topological density on one hand and a similar analysis made possible by the overlap-fermionic topological charge density both with and without variable ultraviolet cutoff $\lambda_{cut}$. The matching is twofold, provided by fitting the density-density two-point functions on one hand and by a point-by-point fitting of the topological densities according to the two methods. We point out the similar cluster structure of the topological density for moderate smearing and $200 \mathrm{MeV} < \lambda_{cut} < 600 \mathrm{MeV}$, respectively. We demonstrate the relation of the gluonic topological density for extensive smearing to the location of the overlap zero modes and the lowest overlap non-zero mode as found for the unsmeared configurations.