Nature of the finite temperature transition in QCD with strange quark

TL;DR

This study investigates the nature of the finite temperature QCD transition with Wilson quarks across different flavor configurations, revealing a first order transition in certain cases and contrasting previous staggered quark results.

Contribution

It provides new evidence that the QCD phase transition can be first order for physical quark masses using Wilson quarks, differing from earlier staggered quark findings.

Findings

Transition is smooth for Nf=2 in the chiral limit.

First order transition observed for Nf=3 at low quark masses.

Evidence suggests a first order transition in real-world QCD with Nf=2+1.

Abstract

The finite temperature transition in QCD is studied using Wilson quarks for the cases of $N_F=2$, 3 and 2+1. For $N_F=2$ the transition is smooth in the chiral limit on both $\nt=4$ and 6 lattices. For $N_F=3$, clear two state signals are observed for $\beta\leq4.7$ on $8^2\times10 \times4$ and $12^3\times4$ lattices, which implies the transition is first order for $m_q \simm{<} 140$ MeV. For $N_F=2+1$ we study two cases of $m_s \simeq 150$ and 400 MeV with $m_u=m_d \simeq 0$. In contrast to a previous result with staggered quarks, two state signals are clearly observed for both cases, suggesting a first order QCD phase transition in the real world.