The phase structure of lattice QCD with two flavours of Wilson quarks and renormalization group improved gluons

TL;DR

This study examines how replacing the Wilson plaquette gauge action with the DBW2 action affects the phase structure in lattice QCD with two Wilson quark flavors, showing reduced pion mass and smoother phase transition.

Contribution

It demonstrates that using the DBW2 gauge action alters the phase structure, lowering the minimal pion mass and the plaquette jump, and is computationally more efficient.

Findings

Reduced minimal pion mass with DBW2 action

Decreased plaquette jump indicating smoother transition

Lower computational costs for simulations

Abstract

The effect of changing the lattice action for the gluon field on the recently observed [1] first order phase transition near zero quark mass is investigated by replacing the Wilson plaquette action by the DBW2 action. The lattice action for quarks is unchanged: it is in both cases the original Wilson action. It turns out that Wilson fermions with the DBW2 gauge action have a phase structure where the minimal pion mass and the jump of the average plaquette are decreased, when compared to Wilson fermions with Wilson plaquette action at similar values of the lattice spacing. Taking the DBW2 gauge action is advantageous also from the point of view of the computational costs of numerical simulations.