2ND-ORDER QCD CORRECTIONS TO SCALAR AND PSEUDOSCALAR HIGGS DECAYS INTO MASSIVE BOTTOM QUARKS

Quark mass effects in O(alpha(s)(2)) QCD corrections to the decay rate s of intermediate Higgs bosons are studied, The total hadronic rate an d the partial decay rate into bottom quarks are analyzed for the Stand ard (scalar) Higgs boson as well as for pseudoscalar Higgs bosons. The calculations of three different contributions are presented. First, t he flavour singlet diagrams containing two closed fermion loops are ca lculated for a nonvanishing bottom mass in the heavy top limit. Their leading contribution, which is of the same order as the quasi-massless nonsinglet corrections, and the subleading terms are found. Large log arithms arise due to the separation of the pure gluon final state from the bottom final states. Second, quadratic bottom mass corrections or iginating from nonsinglet diagrams are presented, Third, nonsinglet co rrections induced by virtual heavy top quarks are calculated in leadin g and subleading orders. It is demonstrated that, in order a alpha(s)( 2), the first contribution numerically dominates over the second and t he third ones.