Gribov copies, Lattice QCD and the gluon propagator

TL;DR

This study investigates the impact of Gribov copies on the lattice QCD gluon propagator, finding minimal effects overall but significant variations at low momenta, and supports a massive gluon propagator model at high momenta.

Contribution

It provides a detailed analysis of Gribov copy effects on the gluon propagator in lattice QCD, highlighting their limited overall impact but notable influence at low momenta, and supports a massive gluon propagator model.

Findings

Gribov copies cause less than 10% variation in the gluon propagator.

Effects are significant mainly at momenta below 2.6 GeV.

Data supports a massive gluon propagator with a mass of 1.1 GeV.

Abstract

We address the problem of Gribov copies in lattice QCD. The gluon propagator is computed, in the Landau gauge, using 302 ($\beta = 5.8$) $12^4$ configurations gauge fixed to different copies. The results of the simulation shows that: i) the effect of Gribov copies is small (less than 10%); ii) Gribov copies change essentially the lowest momenta components ($q < 2.6$ GeV); iii) within the statistical accuracy of our simulation, the effect of Gribov copies is resolved if statistical errors are multiplied by a factor of two or three. Moreover, when modelling the gluon propagator, different sets of Gribov copies produce different sets of parameters not, necessarily, compatible within one standard deviation. Finally, our data supports a gluon propagator which, for large momenta, behaves like a massive gluon propagator with a mass of 1.1 GeV.