Instanton dominance of topological charge fluctuations in QCD?

TL;DR

This study investigates the local chirality of near-zero eigenvectors in lattice QCD, finding that instantons likely dominate topological charge fluctuations, especially on finer lattices with improved methods reducing lattice artifacts.

Contribution

The paper demonstrates that instanton dominance in topological charge fluctuations remains plausible when using refined lattice techniques and addressing non-normality issues.

Findings

Clear double peak structure observed on lattices finer than 0.1 fm.

Lattice artifacts reduced by using biorthogonal eigenvector systems.

Instanton dominance not ruled out by local chirality measurements.

Abstract

We consider the local chirality of near-zero eigenvectors from Wilson-Dirac and clover improved Wilson-Dirac lattice operators as proposed recently by Horv\'ath et al. We studied finer lattices and repaired for the loss of orthogonality due to the non-normality of the Wilson-Dirac matrix. As a result we do see a clear double peak structure on lattices with resolutions higher than 0.1 fm. We found that the lattice artifacts can be considerably reduced by exploiting the biorthogonal system of left and right eigenvectors. We conclude that the dominance of instantons on topological charge fluctuations is not ruled out by local chirality measurements.