Thermodynamic properties of QCD with two flavors of Wilson-type lattice quarks

I report on a study of finite temperature QCD by the CP-PACS Collaboration toward a precise determination of the equation of state with dynamical u,d quarks. Based on a systematic simulation using improved Wilson-type quarks on lattices with temporal size $N_t=4$ and 6, the energy density and pressure are calculated as functions of temperature and renormalized light quark mass in the range $T/T_c \approx 0.7$--2.5 and $m_{\rm PS}/m_{\rm V} = 0.65$--0.95. Results for $N_t=4$ are found to contain significant scaling violations, while results for $N_t=6$ are suggested to be not far from the continuum limit. On the other hand, the quark mass dependence in the EOS turned out to be small for $m_{\rm PS}/m_{\rm V} \simlt 0.8$.