Signatures of supersymmetry and Yukawa unification in Higgs decays

Abstract

We show that the branching ratio R b/τ≡BR(h 0→ b ̄ b)/BR(h 0→τ +τ − ) 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/ τ 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 β. Such large corrections are motivated in supersymmetric unified schemes wherein the Yukawa couplings of the b-quark and the τ-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 0 into charm quarks, as well as of the other Higgs bosons ( H 0, A 0) into b ̄ b , τ + τ −, c ̄ c can provide additional information about the supersymmetric nature of the Higgs sector.