Evidence of BRST-Symmetry Breaking in Lattice Minimal Landau Gauge

TL;DR

This paper provides the first numerical evidence of BRST-symmetry breaking in lattice Yang-Mills theory within minimal Landau gauge, showing a 1/p^4 infrared singularity in the Bose-ghost propagator.

Contribution

It demonstrates BRST-symmetry breaking through lattice simulations and relates the Bose-ghost propagator to a massive gluon and infrared-free ghost propagator.

Findings

Bose-ghost propagator exhibits a 1/p^4 infrared singularity.

Data fit well with a model combining a massive gluon and free ghost.

First numerical evidence of BRST-symmetry breaking in this context.

Abstract

By evaluating the so-called Bose-ghost propagator, we present the first numerical evidence of BRST-symmetry breaking for Yang-Mills theory in minimal Landau gauge, i.e. due to the restriction of the functional integration to the first Gribov region in the Gribov-Zwanziger approach. Our data are well described by a simple fitting function, which can be related to a massive gluon propagator in combination with an infrared-free (Faddeev-Popov) ghost propagator. As a consequence, the Bose-ghost propagator, which has been proposed as a carrier of the confining force in minimal Landau gauge, displays a 1/p^4 singularity in the infrared limit.