The interplay between the <A^2> condensate and instantons

TL;DR

This paper investigates the relationship between the dimension two gluon condensate and instantons using analytical methods, revealing a two-component structure influenced by instantons and quantum fluctuations.

Contribution

It introduces a combined analytical and instanton liquid model approach to study the gluon condensate, highlighting the dual origin from instantons and quantum fluctuations.

Findings

Identification of a two-component gluon condensate structure

Quantitative analysis within the instanton liquid model

Partial resolution of the infrared problem in instanton physics

Abstract

Using the Local Composite Operator formalism, we analytically study the dimension two gluon condensate in the presence of instantons. We first use the dilute gas approximation and partially solve the infrared problem of instanton physics. In order to find quantitative results, however, we turn to an instanton liquid model, where we find a two-component picture of the condensate: one component comes from instantons, a second component is non-perturbatively generated by quantum fluctuations around the instantons.