Flavour degrees of freedom and the transition temperature in QCD

Summary, in English

We study the finite temperature transition in QCD with four flavours of dynamical quarks. Our simulation is performed on an 8×16 ³ lattice for quarks of mass ma=0.01. At the coupling β _c =5.15, we find long-lived metastable states, as well as an abrupt change in the entropy density, suggesting a first order phase transition. Using presently available results from corresponding calculations of the hadron masses and the chiral condensate, this gives us a transition temperature T _c ≅100 MeV, which is a factor two lower than the transition temperature found in quenched QCD.