Gluon Field Strength Correlation Functions within a Constrained Instanton Model

TL;DR

This paper introduces a constrained instanton model for the QCD vacuum, providing a stable solution that accurately describes gluon field correlations and aligns with lattice results at small distances.

Contribution

The paper develops a new constrained instanton solution in the QCD vacuum and calculates gluon correlators, improving understanding of vacuum fluctuations and stability.

Findings

The constrained instanton solution decays exponentially at large distances.

Gluon correlators match lattice results at small distances.

The model predicts a small form factor D1, consistent with lattice data.

Abstract

We suggest a constrained instanton (CI) solution in the physical QCD vacuum which is described by large-scale vacuum field fluctuations. This solution decays exponentially at large distances. It is stable only if the interaction of the instanton with the background vacuum field is small and additional constraints are introduced. The CI solution is explicitly constructed in the ansatz form, and the two-point vacuum correlator of gluon field strengths is calculated in the framework of the effective instanton vacuum model. At small distances the results are qualitatively similar to the single instanton (SI) case, in particular, the form factor $D_{1}$ is small, which is in agreement with the lattice calculations.