R-CCS Cafe 第235回 第1部

Quantum chromodynamics (QCD) is the theory of the strong interaction between quarks mediated by gluons. At low temperature, the dominant degrees of freedom are colourless bound states of hadrons, at high temperatures or densities hadrons will undergoes a transition into the deconfined phase called Quark-Gluon Plasma (QGP). It is generally believed that the early universe was in the quark gluon plasma phase within a few microseconds after the big bang. The properties of QGP are being studied experimentally at the Relativistic Heavy-Ion Collider (RHIC) at BNL and the Large Hadron Collider (LHC) at CERN. On the energy scales accessible to the experiments the theory is strongly coupled and lattice QCD provides a non-perturbative approach for solving it with stochastic methods.

It has been noted by Pisarski and Wilczek quite a long time ago that the order of QCD phase transition and the transition temperature crucially depends on the number of light quark flavors and the value of quark masses, the quark mass dependence is summarized in the so-called Columbia plot. In this talk I will talk about the recent studies of QCD phase transition of (2+1)-flavor and 3-flavor QCD from the lattice QCD simulations with the Domain wall fermion.