On the topological structure of the QCD vacuum

TL;DR

This paper reviews lattice studies of the QCD vacuum's topological structure, emphasizing improved cooling methods that stabilize instantons and preserve physical features, providing insights into the Yang-Mills vacuum.

Contribution

It introduces scale controlled cooling techniques that serve as gauge invariant filters, enhancing the analysis of topological features in lattice QCD simulations.

Findings

Stable instanton solutions at physical sizes

Effective gauge invariant filtering of noisy configurations

Preservation of instanton-antiinstanton pairs

Abstract

A review of results from lattice studies using improved and scale controlled cooling methods is presented and their significance is discussed. The improvement of the action ensures stable instanton solutions of physical sizes. The scale controlled cooling can be generally used as a gauge invariant low pass filter to extract the physics from noisy MC configurations; in particular it preserves instanton-antiinstanton pairs selected according to their interaction. We apply these methods to analyze various features of the topological structure of the Yang-Mills vacuum in a scaling invariant way.