Massive gluons and quarks and the equation of state obtained from SU(3) lattice QCD

We analyze recent results of SU(3) lattice QCD calculations with a phenomenological parametrization for the quark-gluon plasma equation of state based on a quasiparticle picture with massive quarks and gluons. At high temperature we obtain a good fit to the lattice data using perturbative thermal quark and gluon masses from an improved HTL scheme. At temperatures dose to the confinement phase transition the fitted masses increase above the perturbative value, and a nonzero (but small) bag constant is required to fit the lattice data.