Some results on the distinction of Higgs boson models

We present results on the analysis of the ratio of branching ratios R = BR(H → bb̄)/BR(H → τ+τ−) of Higgs boson decays as a discriminant quantity between supersymmetric and non-supersymmetric models. A detailed analysis in the effective Lagrangian approach shows how one could discriminate between models at the Large Hadron Collider and the e+e− Linear Collider at 500GeV center of mass energy. The search for a Higgs boson is nowadays the main objective of High Energy Physics experiments. Even if a neutral scalar boson is discovered in present or future colliders, the question will still be open: whether it is the Higgs particle of the minimal Standard Model (SM) or whether there is an extended Higgs structure beyond the SM. We approach this question by investigating the neutral Higgs sector of various types of models. In particular, we consider the ratio of branching ratios of a neutral Higgs boson H , R = BR(H → bb̄) BR(H → τ+τ−) , (1) and we analyze in detail the Yukawa-coupling effects and their phenomenological consequences [1]. This ratio receives large renormalization-scheme independent radiative corrections in supersymmetric (SUSY) models at large tanβ, which are absent in the SM or Two-Higgs-doublet models (THDM). These corrections are insensitive to the supersymmetric mass scale. We consider in our analysis the effective Lagrangian approach by relating the quark mass to the Yukawa coupling via ∆mf , the non-decoupling quantity that encodes the leading radiative corrections, hf = mf(Q) v1 1 1 + ∆mf = mf (Q) v cosβ 1 1 + ∆mf , v = (v 1 + v 2 2) 1/2 . (2) Based on talk given at Second Workshop of the Extended ECFA/DESY Study, Saint Malo, April 12-15, 2002 electronic address: [email protected], [email protected], [email protected]