Constraints on two-Higgs-doublet models at large tan beta from W and Z decays

We study constraints on type–II two Higgs doublet models at large tan β from LEP/SLD Z–pole data and from lepton universality violation in W decay. We perform a global fit and find that, in the context of Z decay, the LEP/SLD experimental values for lepton universality violation, R_b, and A_b all somewhat disfavor the model. Contributions from the neutral Higgs sector can be used to constrain the scalar–pseudoscalar Higgs mass splittings. Contributions from the charged Higgs sector allow us to constrain the charged Higgs mass. For tan β = 100 we obtain the 1σ classical (Bayesian) bounds of M_H ± ≥ 670 GeV (370 GeV) and 1 ≥ m_h⁰/m_A⁰ ≥ 0 .68 (0 .64). The 2 σ bounds are weak. Currently, the Tevatron experimental limits on lepton universality violation in W decay provide no significant constraint on the Higgs sector.