Scaling behavior and positivity violation of the gluon propagator in full QCD

TL;DR

This paper investigates the gluon propagator in full QCD, revealing how dynamical quarks reduce infrared enhancement and confirming positivity violation of the gluon spectral function across different lattice configurations.

Contribution

It provides a detailed lattice QCD analysis of the gluon propagator, highlighting the effects of dynamical quarks and lattice spacing on infrared behavior and positivity violation.

Findings

Dynamical quarks reduce infrared enhancement of the gluon propagator.

Positivity violation of the gluon spectral function is observed in both quenched and full QCD.

Lattice spacing effects are minimal in the studied configurations.

Abstract

The Landau-gauge gluon propagator is studied using the coarse and fine dynamical MILC configurations. The effects of dynamical quarks are clearly visible and lead to a reduction of the nonperturbative infrared enhancement relative to the quenched case. Lattice spacing effects are studied and found to be small. The gluon spectral function is shown to clearly violate positivity in both quenched and full QCD.