Topology of full QCD

We study topological properties of SU(3) gauge theory using improved cooling. In the absence of fermions, we measure a topological susceptibility of $(182(8) MeV)^4$andaninstantonsize$\sim 0.6$ fm. In the presence of light staggered fermions and across the chiral transition, the susceptibility drops in a manner consistent with the quenched case, and the instanton size changes little. No significant formation of bound instanton-antiinstanton pairs is observed, in particular not along the Euclidean time direction for $T>T_c$.