Signatures of supersymmetry and Yukawa unification in Higgs decays

We show that the branching ratio R-b/tau = BR(h(0) --> (b) over bar b)/BR(h(0) --> tau(+)tau(-)) of the Higgs boson h(0) may usefully differentiate between the Higgs sectors of the Minimal Supersymmetric Standard Model (MSSM) and non-supersymmetric models such as the Standard Model or its two Higgs doublet extensions. Although at tree level R-b/tau is the same in all these models, only in the MSSM can it receive a large radiative correction, for moderate to large values of the parameter tan beta. Such large corrections are motivated in supersymmetric unified schemes wherein the Yukawa couplings of the b-quark and the tau-lepton are equal at the unification scale; otherwise the b-quark mass prediction is too large by 15-30% for most of parameter space. Thus accurate measurements of the Higgs branching ratios can probe physics at the unification scale. The branching ratio of h(o) into charm quarks, as well as of the other Higgs bosons (H-o,A(o)) into (b) over bar b, tau(+)tau(-), (c) over bar c can provide additional information about the supersymmetric nature of the Higgs sector. (C) 1999 Published by Elsevier Science B.V. All rights reserved.