Quark flavour effects on gluon and ghost propagators

TL;DR

This study investigates how different quark flavors influence gluon and ghost propagators in QCD by non-perturbative lattice simulations with various quark masses, revealing their effects across a wide momentum range.

Contribution

It provides the first comprehensive non-perturbative analysis of quark flavor effects on gluon and ghost propagators in full QCD with multiple dynamical quark flavors.

Findings

Quark flavor effects significantly alter gluon and ghost propagators.

The effective QCD coupling depends on the number and mass of dynamical quarks.

Results bridge the infrared and intermediate momentum regimes in QCD.

Abstract

We compute the full non-perturbative ghost and gluon two-point Green functions by using gauge field configurations with $\nf=2$ and $\nf=2+1+1$ twisted-mass quark flavours. We use simulations with several different light quark masses, heavy quark masses close to that of the strange and charm quarks, and lightest pseudoscalar masses ranging from 270 to 510 [MeV]. Quark flavour effects on both the gluon and the ghost propagators are then investigated in a wide range of momenta, bridging the deep infrared and intermediate momenta domain of QCD interactions in the presence of dynamical quarks. The ghost-gluon vertex is also indirectly probed through a consistency requirement among the lattice data for the gluon and ghost propagators and the ghost propagator Schwinger-Dyson equation. The effective full QCD coupling is finally constructed, and its dependence on the presence of dynamical fermions scrutinized.