Are the Dressed Gluon and Ghost Propagators in the Landau Gauge presently determined in the confinement regime of QCD?

TL;DR

This paper investigates the Landau gauge gluon and ghost propagators in QCD's confinement regime using Schwinger-Dyson equations, highlighting the sensitivity to vertex choices and supporting a mass-like gluon propagator consistent with Cornwall's proposal.

Contribution

It demonstrates the necessity of a non-trivial ghost-gluon vertex for self-consistent solutions and favors an infrared finite ghost solution with a mass-like gluon propagator.

Findings

Infrared finite ghost solution favored

A non-trivial ghost-gluon vertex is required for consistency

Gluon propagator exhibits a mass-like term in solutions

Abstract

The Gluon and Ghost propagators in Landau gauge QCD are investigated using the Schwinger-Dyson equation approach. Working in Euclidean spacetime, we solve for these propagators using a selection of vertex inputs, initially for the ghost equation alone and then for both propagators simultaneously. The results are shown to be highly sensitive to the choices of vertices. We favor the infrared finite ghost solution from studying the ghost equation alone where we argue for a specific unique solution. In order to solve this simultaneously with the gluon using a dressed-one-loop truncation, we find that a non-trivial full ghost-gluon vertex is required in the vanishing gluon momentum limit. The self-consistent solutions we obtain correspond to having a mass-like term in the gluon propagator dressing, in agreement with similar studies supporting the long held proposal of Cornwall.