QCD equation of state in a virial expansion

Understand

We describe recent three-flavor QCD lattice data for the pressure, speed of soun d and interaction measure at nonzero temperature and vanishing chemical potentia l within a virial expansion.

• For the deconfined phase we use a phenomenological model which includes non-pert urbative effects from dimension two gluon condensates that reproduce the free en ergy of quenched QCD very well.
• The hadronic phase is parameterized by a generalized resonance-gas model.
• Furthermore, we extend this approach to finite quark densities introducing an ex plicit $\mu$-dependence of the interaction.