Probing for Instanton Quarks with epsilon-Cooling

TL;DR

This paper investigates the structure of instantons with fractional topological charge in SU(2) gauge theory using epsilon-cooling, revealing constituents at finite and zero temperature through various analytical tools.

Contribution

It introduces epsilon-cooling as a method to study instanton constituents and demonstrates how cooling histories can identify fractional topological charges.

Findings

Identification of instanton constituents with fractional topological charge.

Epsilon-cooling effectively reveals instanton substructure.

Analysis of zero modes and Polyakov loop supports the presence of constituents.

Abstract

We use epsilon-cooling, adjusting at will the order a^2 corrections to the lattice action, to study the parameter space of instantons in the background of non-trivial holonomy and to determine the presence and nature of constituents with fractional topological charge at finite and zero temperature for SU(2). As an additional tool, zero temperature configurations were generated from those at finite temperature with well-separated constituents. This is achieved by "adiabatically" adjusting the anisotropic coupling used to implement finite temperature on a symmetric lattice. The action and topological charge density, as well as the Polyakov loop and chiral zero-modes are used to analyse these configurations. We also show how cooling histories themselves can reveal the presence of constituents with fractional topological charge. We comment on the interpretation of recent fermion zero-mode studies for thermalized ensembles at small temperatures.