Deconfining Chiral Transition in QCD on the Lattice

The deconfining chiral transition in finite-temperature QCD is studied on the lattice using Wilson quarks. After discussing the nature of chiral limit with Wilson quarks, we first study the case of two degenerate quarks N_F = 2, and find that the transition is smooth in the chiral limit on both N_t = 4 and 6 lattices. For N_F = 3, on the other hand, clear two state signals are observed for m_q ≲ 140 MeV on N_t = 4 lattices. For a more realistic case of N_F = 2+1, i.e. two degenerate u and d-quarks and a heavier s-quark, we study the cases m_s ≃ 150 and 400 MeV with m_u = m_d ≃ 0: In contrast to a previous result with staggered quarks, clear two state signals are observed for both cases, suggesting a first order QCD phase transition in the real world.