Effects of non-perturbatively improved dynamical fermions in UKQCD simulations

TL;DR

This study investigates how non-perturbatively improved dynamical fermions influence various QCD observables on a fixed lattice volume, revealing significant effects on the static potential, glueball mass, and topological susceptibility, but minimal impact on the light hadron spectrum.

Contribution

It provides the first detailed comparison of dynamical fermion effects using non-perturbatively improved actions on matched lattice ensembles.

Findings

Dynamical quarks affect the short-distance static potential.

Scalar glueball mass and topological susceptibility are influenced by dynamical fermions.

Little change observed in the light hadron spectrum within studied quark mass range.

Abstract

We present results for QCD with 2 degenerate flavours of quark using a non-perturbatively improved action on a lattice volume of $16^3\times32$ where the bare gauge coupling and bare dynamical quark mass have been chosen to maintain a fixed physical lattice spacing and volume (1.71 fm). By comparing measurements from these matched ensembles, including quenched ones, we find evidence of dynamical quark effects on the short distance static potential, the scalar glueball mass and the topological susceptibility. There is little evidence of effects on the light hadron spectrum over the range of quark masses studied ($m_{\pi}/m_{\rho}\geq 0.60$).