Lattice QCD with small number of flavours

The finite temperature behaviour of lattice QCD with dynamical quarks for small number of flavours Nf is investigated. Simulations have been performed on lattices of size Nσ3 . 4 with Nσ=8 and 12 and staggered fermions of mass ma = 0.1 using a hybrid algorithm. We find that the two state signal at the critical point of the pure gauge theory, which is taken as sign for a first order phase transition, persists for the values of Nf we have investigated, namely Nf=0.5, 1 and 2. It is, however, considerably weaker for Nf=1 and 2. Moreover, for Nf=2 the discontinuity at βc decreases with increasing lattice size. This puts doubt on the first order nature of the Nf=2 transition at intermediate masses. (orig.)