Quark mass effects on the topological susceptibility in QCD

We investigate topology in lattice simulations of QCD with two flavours of dynamical Wilson fermions. At various sea quark masses we find reasonable agreement between results for the topological charge from fermionic and gluonic definitions, the latter with cooling. We study correlations of the topological charge with light hadronic observables and find effects in the flavour singlet pseudoscalar channel. The quark mass dependence of the topological susceptibility, $\chi$, is in agreement with the leading order small m_pi expectation, chi=(f_pi m_pi)^2/4.