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

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 ${\ensuremath{\lambda}}_{\mathrm{cut}}$. 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 $200\text{ }\text{ }\mathrm{MeV}<{\ensuremath{\lambda}}_{\mathrm{cut}}<600\text{ }\text{ }\mathrm{MeV}$, 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 nonzero mode as found for the unsmeared configurations.