QUARK MASS EFFECTS IN FERMIONIC DECAYS OF THE HIGGS-BOSON IN O(ALPHA(S)(2)) PERTURBATIVE QCD

The results of analytical evaluation of O(alpha(s)(2)) QCD contributio ns due to the nonvanishing quark masses to Gamma(H-->qf (q) over bar f ) are presented. The ''triangle anomaly'' type contributions are inclu ded. As a byproduct the O(alpha(s)(3)) logarithmic contributions are e valuated. The results are presented both in terms of running and pole quark masses. The partial decay modes H --> b (b) over bar and H --> c (c) over bar are considered. The calculated corrections decrease the absolute value of large and negative O(a:) massless limit coefficient by less than or equal to 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 --> t (t) over bar decay mode for the higher Higgs mass region where the mass effects are large and importa nt The high order corrections remove a very large discrepancy between the results for Gamma(H-->qf (q) over bar f) in terms of running and p ole quark masses almost completely and reduce the scale dependence fro m about 40% to nearly 5%. The remaining theoretical uncertainties are discussed.