Implications on the supersymmetric Higgs sector from top quark decays at the Tevatron

From the τ-lepton analysis of the charged Higgs decay of the top quark at the Tevatron, t→H+b→τ+ντ b, it is possible to set rather stringent bounds on the (tanβ,MH±)-plane, if one assumes that H± is a charged member of a generic two-Higgs-doublet model. However, if we consider the possibility that H± is supersymmetric, then we find that the allowed region in the (tanβ,MH±)-plane can be significantly modified by the MSSM quantum corrections. Throughout our analysis we correlate the top quark results with the limits imposed by radiative and semileptonic B-meson decays. Remarkably, one can envision situations in the MSSM parameter space where H± completely eludes those bounds, i.e. a charged Higgs with a mass below the top quark mass could coexist with essentially any value of tanβ.