Topological susceptibility in full QCD at zero and finite temperature

We present a study of the topological susceptibility $\chi$ on the lattice for full QCD with 2 and 4 flavours of staggered fermions at zero and finite temperature T. We find that $\chi$ presents a sharp drop across the deconfinement transition. We also study the dependence of $\chi$ on the quark mass at T=0: we have no conclusive evidence for the expected chiral behaviour.