Theta dependence of the vacuum energy in the SU(3) gauge theory from the lattice

TL;DR

This study uses lattice simulations to analyze the topological charge distribution in SU(3) Yang-Mills theory, revealing deviations from Gaussian behavior and challenging instanton model predictions, aligning instead with large Nc expansion expectations.

Contribution

The paper provides a high-precision lattice computation of the topological charge distribution in SU(3) gauge theory, testing theoretical models of vacuum energy dependence on theta.

Findings

Significant deviations from Gaussian distribution observed.

Results disfavor instanton model predictions.

Findings are compatible with large Nc expansion expectations.

Abstract

We report on a precise computation of the topological charge distribution in the SU(3) Yang--Mills theory. It is carried out on the lattice with high statistics Monte Carlo simulations by employing the definition of the topological charge suggested by Neuberger's fermions. We observe significant deviations from a Gaussian distribution. Our results disfavour the theta behaviour of the vacuum energy predicted by instanton models, while they are compatible with the expectation from the large Nc expansion.