We have calculated the pressure and energy density in four-flavour QCD using improved fermion and gauge actions. We observe a strong reduction of finite cut-off effects in the high temperature regime, similar to what has been noted before for the SU(3) gauge theory. Calculations have been performed on 163×4 and 16^4 lattices for two values of the quark mass, ma=0.05 and 0.1. A calculation of the string tension at zero temperature yields a critical temperature Tc/σ=0.407±0.010 for the smaller quark mass value.
@article{arxiv.hep-lat/9612018,
title = {Thermodynamics of Four-Flavour QCD with Improved Staggered Fermions},
author = {J. Engels and R. Joswig and F. Karsch and E. Laermann and M. Lütgemeier and B. Petersson},
journal= {arXiv preprint arXiv:hep-lat/9612018},
year = {2009}
}