We present results obtained in QCD with two flavors of non-perturbatively improved Wilson fermions at finite temperature on $16^3 times 8$ and $24^3 times 10$ lattices. We determine the transition temperature in the range of quark masses $0.6<m_pi/m_rho<0.8$ at lattice spacing a$approx$0.1 fm and extrapolate the transition temperature to the continuum and to the chiral limits. We also discuss the order of phase transition.
We present a study of the topological susceptibility in lattice QCD with two degenerate flavors of dynamical quarks. The topological charge is measured on gauge configurations generated with a renormalization group improved gauge action and a mean fi
eld improved clover quark action at three values of $beta=6/g^2$, corresponding to lattice spacings of $a approx 0.22$, 0.16 and 0.11 fm, with four sea quark masses at each $beta$. The study is supplemented by simulations of pure SU(3) gauge theory with the same gauge action at 5 values of $beta$ with lattice spacings 0.09 fm$simlt a simlt$0.27 fm. We employ a field theoretic definition of the topological charge together with cooling. For the topological susceptibility in the continuum limit of pure SU(3) gauge theory we obtain $chi_t^{1/4} = 197^{+13}_{-16}$ MeV where the error shows statistical and systematic ones added in quadrature. In full QCD $chi_t$ at heavy sea quark masses is consistent with that of pure SU(3) gauge theory. A decrease of $chi_t$ toward light quark masses, as predicted by the anomalous Ward-Takahashi identity for U(1) chiral symmetry, becomes clearer for smaller lattice spacings. The cross-over in the behavior of $chi_t$ from heavy to light sea quark masses is discussed.
We present results obtained in QCD with two flavors of non-perturbatively improved Wilson fermions at finite temperature on $16^3 times 8$ and $24^3 times 10$ lattices. We determine the transition temperature in the range of quark masses $0.6<m_pi/m_
rho<0.8$ at lattice spacing a$approx$0.1 fm and extrapolate the transition temperature to the continuum and to the chiral limits.
We study the dynamics of SU(2) gauge theory with NF=6 Dirac fermions by means of lattice simulation to investigate if they are appropriate to realization of electroweak symmetry breaking. The discrete analogue of beta function for the running couplin
g constant defined under the Schroedinger functional boundary condition are computed on the lattices up to linear size of L/a=24 and preclude the existence of infrared fixed point below 7.6. Gluonic observables such as heavy quark potential, string tension, Polyakov loop suggest that the target system is in the confining phase even in the massless quark limit.
We present updated results of the CP-PACS calculation of the light hadron spectrum in $N_{rm f}=2$ full QCD. Simulations are made with an RG-improved gauge action and a tadpole-improved clover quark action for sea quark masses corresponding to $m_{rm
PS}/m_{rm V} approx 0.8$--0.6 and the lattice spacing $a=0.22$--0.09 fm. A comparison of the full QCD spectrum with new quenched results, obtained with the same improved action, shows clearly the existence of sea quark effects in vector meson masses. Results for light quark masses in $N_{rm f}=2$ QCD are also presented.
We present results of a first study of equation of state in finite-temperature QCD with two flavors of Wilson-type quarks. Simulations are made on lattices with temporal size $N_t=4$ and 6, using an RG-improved action for the gluon sector and a meanf
ield-improved clover action for the quark sector. The lines of constant physics corresponding to fixed values of the ratio $m_{rm PS}/m_{rm V}$ of the pseudo-scalar to vector meson masses at zero temperature are determined, and the beta functions which describe the renormalization-group flow along these lines are calculated. Using these results, the energy density and the pressure are calculated as functions of temperature along the lines of constant physics in the range $m_{rm PS}/m_{rm V} = 0.65$--0.95. The quark mass dependence in the equation of state is found to be small for $m_{rm PS}/m_{rm V} simlt 0.8$. Comparison of results for $N_t=4$ and $N_t=6$ lattices show significant scaling violation present in the $N_t=4$ results. At high temperatures the results for $N_t=6$ are quite close to the continuum Stefan-Boltzmann limit, suggesting the possibility of a precise continuum extrapolation of thermodynamic quantities from simulations at $N_tsimgt 6$.