Phase Diagram of QCD at Finite Temperatures with Wilson Fermions

TL;DR

This paper investigates the phase diagram of Quantum Chromodynamics (QCD) with Wilson fermions at finite temperatures, revealing the order of phase transitions varies with the number of flavors and quark masses, with implications for understanding QCD thermodynamics.

Contribution

The study provides new lattice simulation results on the order of the chiral phase transition in QCD with Wilson fermions across different flavor numbers and quark masses, including effects of RG improvements.

Findings

First-order transition for 3 ≤ N_F ≤ 6

Continuous transition for N_F=2

First-order transition for realistic quark masses

Abstract

Phase diagram of QCD with Wilson fermions for various numbers of flavors $N_F$ is discussed. Our simulations mainly performed on a lattice with the temporal size $N_t =4$ indicate the following: The chiral phase transition is of first order when $3 \le N_F \le 6$, while it is continuous when $N_F=2$. For the realistic case of massless u and d quarks and the strange quark with $m_q = 150$ MeV, the phase transition is first order. The sharp transition in the intermediate mass region for $N_F=2$ at $N_t=4$ observed by the MILC group disappears when an RG improvement is made for the pure gauge action.