Chiral phase transition of $N_f$=2+1 QCD with the HISQ action

TL;DR

This study investigates the universal properties of the chiral phase transition in 2+1 flavor QCD using HISQ lattice simulations, analyzing how quark mass and volume affect chiral observables near the transition.

Contribution

It provides new insights into the chiral phase transition in 2+1 QCD with physical strange quark mass and varying light quark masses, emphasizing universal scaling behavior.

Findings

Chiral observables follow O(N) scaling near the transition.

Universal scaling influences physical observables at physical quark masses.

Chiral condensates and susceptibilities depend on quark mass and volume.

Abstract

We present studies of universal properties of the chiral phase transition in $N_f$=2+1 QCD based on the simulations using Highly Improved Staggered fermions on lattices with temporal extent $N_\tau$=6. We analyze the quark mass and volume dependence of the chiral condensates and chiral susceptibilities in QCD with two degenerate light quarks and a strange quark. The strange quark mass is chosen to be fixed to its physical value ($m^{phy}_s$) and five values of light quark masses ($m_l$) that are varied in the interval 1/20$\gtrsim m_l/m^{phy}_s \gtrsim$1/80. Here various quark masses correspond to pseudo Goldstone pion masses ranging from about 160 MeV to about 80 MeV. The O(N) scaling of chiral observables and the influence of universal scaling on physical observables in the region of physical quark mass values are also discussed.