Top mass effects in Higgs production at next-to-next-to-leading order QCD: Virtual corrections

Top quark mass suppressed terms are calculated for the virtual amplitude for Higgs production in gluon fusion at three-loop level, i.e. O(αs3). The method of asymptotic expansions in its automated form is used to evaluate the first three non-vanishing orders in terms of MH2/Mt2, where the first order corresponds to the known results of the effective Lagrangian approach.