FINITE TEMPERATURE PHASE TRANSITION IN QCD WITH STRANGE QUARK: STUDY WITH WILSON FERMIONS ON THE LATTICE

The effect of the strange quark in the finite temperature phase transition of QCD is studied on the lattice. Using the one-plaquette gauge action and the Wilson quark action, the transition in the chiral limit is shown to be continuous for the case of degenerate two flavors, $N_F=2$, while it is of first order for $N_F \geq 3$. For a more realistic case of massless up and down quarks and a light strange quark, $N_F=2+1$, clear two state signals are observed both for $m_s \simeq 150$ and 400 MeV. In contrast to a previous result with staggered quarks, this suggests a first order transition in the real world. In order to see the implication of these results to the continuum limit, we started to study these issues using improved actions. First results using a RG improved gauge action combined with the standard Wilson quark is presented for the case of $N_F=2$: With this action the finite temperature transition is shown to be continuous in the chiral limit confirming the result of the standard action. Furthermore, not like the case of the standard action where lattice artifacts make the transition once very strong at intermediate values of the hopping parameter $K$ on $N_t=4$ and 6 lattices, a smooth crossover is found for the improved action when we increase $1/K-1/K_c$, in accord with a naive expectation about the fate of second order chiral transition at finite $m_q$.Comment: uuencoded compressed PS file, 9 pages, 10 figures, Talk given at the International Conference {\it Confinement95}, RCNP, Osaka, March 22-24, 199

Developments in Finite Temperature QCD on the Lattice with Dynamical Quarks

I report on some recent developments in nonperturbative studies of finite temperature QCD with dynamical quarks on the lattice. I discuss new studies of improved lattice actions and their application to finite temperature QCD. I also summarize the status of lattice investigations about the order of the finite temperature QCD transition for the case of two flavors of degenerate light quarks, using both staggered and Wilson lattice fermions.Comment: Review presented at the International Workshop on ``Physics of Relativistic Heavy Ion Collisions'', Kyoto, Japan, 9--11 June 1997. To be published in the Proceedings [Prog. Theor. Phys., Suppl.

An Introduction to Finite Temperature Quantum Chromodynamics on the Lattice

In these lectures, we introduce finite temperature QCD on the lattice to non-experts of the subject. We first formulate lattice QCD both at zero and finite temperatures. Then a section is devoted to the topic of improved lattice actions which are becoming an essential ingredient of precision studies of QCD on the lattice. We then discuss about finite temperature SU(3) gauge theory, i.e. QCD without dynamical quarks (quenched QCD). Finally, we report recent status of studies in full QCD taking into account the effects of dynamical quarks.Comment: Lectures presented at the 1997 Yukawa International Seminar (YKIS'97) on ``Non-Perturbative QCD --- Structure of the QCD Vacuum ---'', YITP, Kyoto, Japan, 2--12 Dec. 1997. To be published in the proceedings [Prog. Theor. Phys. Suppl.

Lattice results on the phase structure and equation of state in QCD at finite temperature

I review recent developments in the studies of the phase structure and equation of state in finite temperature QCD on the lattice.Comment: 6 pages, 12 figures, plenary talk given at the conference "Quark Confinement and the Hadron Spectrum IX", August 30 - September 3, 2010, Madrid, Spain; version to appear in the AIP proceeding

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.Comment: Talk presented at Statistical QCD, Aug. 26-30, 2001, Bielefeld, Germany. LaTeX2e, 6 pages, 4 PS figures, espcrc1.sty neede