EQUATION OF STATE IN THE QUARK-GLUON PLASMA

Results from quenched simulations of QCD at finite temperature are pre sented. We calculated pressure and energy density. With the standard W ilson action we worked on several large lattices, with temporal extent N-tau = 4, 6 and 8 and spatial extent N-sigma = 16 and 32. This enabl es to control finite lattice spacing effects and to extrapolate the re sults to the continuum limit. We find a deviation from ideal gas behav iour of about 15%, even at temperatures as high as T similar to 5T(c). a calculation of the critical temperature on lattices with temporal e xtent N-tau = 8 and 12 and the string tension on 32(4) lattices at the corresponding critical couplings is performed to fix the temperature scale. An extrapolation to the continuum limit yields T-c/root sigma = 0.629(3). These results are then compared to simulations with improve d lattice actions. We can demonstrate that at high temperatures the cu t-off effects can be reduced considerably.