Quark mass effects in fermionic decays of the Higgs boson in O(α2s) perturbative QCD

The results of analytical evaluation of O(α2s) QCD contributions due to the nonvanishing quark masses to ГH→qƒqƒ are presented. The “triangle anomaly” type contributions are included. As a byproduct the O(α3s) logarithmic contributions are evaluated. The results are presented both in terms of running and pole quark masses. The partial decay modes H→bb and H→cc are considered. The calculated corrections decrease the absolute value of large and negative O(αs2) massless limit coefficient by ≤ 1% in the intermediate mass region and by 1%–20% in the low mass region which, however, is experimentally ruled out. The results are relevant for H→tt decay mode for the higher Higgs mass region where the mass effects are large and important. The high order corrections remove a very large discrepancy between the results for ГH→qƒqƒ in terms of running and pole quark masses almost completely and reduce the scale dependence from about 40% to nearly 5%. The remaining theoretical uncertainties are discussed.