Narrow Results

The chiral phase transition temperature $T_c^0$ is a fundamental quantity of QCD. To determine this quantity we have performed simulations of (2 + 1)-flavor QCD using the Highly Improved Staggered Quarks (HISQ/tree) action on N_τ=6, 8 and 12 lattices with aspect ratios N_σ/N_τ ranging from 4 to 8. In our simulations we fix the strange quark mass to its physical value $m_s^{\text{phy}}$, and vary the values of two degenerate light quark masses m_l from $m_s^{\text{phy}}/20$ to $m_s^{\text{phy}}/160$ which correspond to a Goldstone pion mass m_π ranging from 160 MeV to 55 MeV in the continuum limit. We employ two estimators T₆₀ and T_δ to extract the chiral phase transition temperature $T_c^0$, after taking the chiral limit, thermodynamic limit and continuum limit, we present our current estimate for $T_c^0={132}_{-6}^{+3}\text{MeV}$.

Efficient cluster algorithms have recently been discovered to solve strong coupling lattice QCD with staggered fermions in the chiral limit from first principles. This allows us for the first time to uncover the universal properties close to chiral phase transitions and make connections with chiral perturbation theory. In this article we will review some of the recent progress and outline some possible directions for future work.