QCD Thermodynamics with 2 and 3 Quark Flavors

TL;DR

This paper investigates how the number of quark flavors affects QCD thermodynamics, analyzing pressure, critical temperature, and phase transition properties using lattice simulations with improved actions.

Contribution

It provides new insights into flavor dependence of QCD thermodynamics and evidence for the universality class of the 3-flavor chiral critical point.

Findings

Bulk thermodynamics with 2 light and 1 heavier strange quark matches 3-flavor QCD above 2 Tc.

Transition temperature for 2+1 flavors is closer to 2-flavor QCD.

Chiral critical point belongs to the 3d Ising universality class.

Abstract

We discuss the flavor dependence of the pressure and critical temperature calculated in QCD with 2, 2+1 and 3 flavors using improved gauge and staggered fermion actions on lattices with temporal extent Nt=4. For T > 2 Tc we find that bulk thermodynamics of QCD with 2 light and a heavier strange quark is well described by 3-flavor QCD while the transition temperature is closer to that of 2-flavor QCD. Furthermore, we present evidence that the chiral critical point of 3-flavor QCD, i.e. the second order endpoint of the line of first order chiral phase transitions, belongs to the universality class of the 3d Ising model.