Finite Temperature Transition in Two Flavor QCD with Renormalization Group Improved Action

TL;DR

This study investigates the finite temperature transition in two-flavor QCD using a renormalization group improved action, revealing a smooth crossover behavior contrasting with sharp transitions seen with standard actions.

Contribution

It demonstrates that a renormalization group improved action results in a smooth crossover in finite temperature QCD, differing from the sharp transition observed with standard actions at similar lattice spacings.

Findings

Polyakov loop and pion screening mass vary smoothly across the transition.

Quark screening mass in high and low temperature phases agree well.

Transition behavior differs markedly from standard action results.

Abstract

The finite temperature transition or crossover in QCD with two degenerate Wilson quarks is investigated using a renormalization group improved action. At $\beta=2.0$ and 2.1 where $a^{-1} \sim 1.0-1.2$ GeV, the expectation value of the Polyakov loop and the pion screening mass on an $8^3 \times 4$ lattice vary smoothly with the hopping parameter through the transition/crossover. The quark screening mass in the high temperature phase agrees well with that in the low temperature phase calculated on an $8^4$ lattice. The smooth transition of the observables is totally different from the sharp transition found for the standard action at $\beta=5.0$ and 5.1 where $a^{-1}$ is also $1.0-1.2$ GeV.