Three-loop O(αs2GFMt2) corrections to hadronic Higgs decays Original Research Article

We calculate the top-quark-induced three-loop corrections of O(αs2GFMt2) to the Yukawa couplings of the first five quark flavours in the framework of the minimal standard model with an intermediate-mass Higgs boson, with mass MH ⪡ 2Mt. The calculation is performed using an effective-Lagrangian approach implemented with the hard-mass procedure. As an application, we derive the O(αs2GFMt2) corrections to the H → qq− partial decay widths, including the case q = b. The couplings of the Higgs boson to pairs of leptons and intermediate bosons being known to O(αs2GFMt2), this completes the knowledge of such corrections in the Higgs sector. We express the results both in the MS and on-shell schemes of mass renormalization. We recover the notion that the QCD perturbation expansions exhibit a worse convergence behaviour in the on-shell scheme than they do in the MS scheme.