Landau Gauge Gluon and Ghost Propagators from Lattice QCD

TL;DR

This paper presents lattice QCD computations of Landau gauge gluon and ghost propagators, focusing on low momentum behavior, systematic effects, and the running coupling in pure Yang-Mills and full QCD.

Contribution

It provides new lattice data for the gluon propagator below 300 MeV and analyzes systematic effects and the behavior of the running coupling at low momenta.

Findings

Gluon propagator data below 300 MeV is presented.

The running coupling decreases below 550 MeV.

Systematic effects like finite-size and Gribov copies are discussed.

Abstract

We report on recent numerical computations of the Landau gauge gluon and ghost propagators as well as of the ghost-gluon vertex function in pure SU(3) Yang-Mills theory and in full QCD on the lattice. Special emphasis is paid to the low momentum region. In particular, we present new data for the gluon propagator at momenta below 300 MeV. We also discuss different systematic effects as there are finite-size, lattice discretization and Gribov copy but also unquenching effects. A MOM-scheme running coupling \alpha_s(q^2) based on the ghost-gluon vertex is calculated and found to decrease for momenta below 550 MeV, even though the renormalization constant of the vertex deviates only weakly from being constant.