QCD Corrections in two-Higgs-doublet extensions of the Standard Model with Minimal Flavor Violation

Abstract

We present the QCD corrections to R_b and to the Delta B=1 effective Hamiltonian in models with a second Higgs field that couples to the quarks respecting the criterion of Minimal Flavor Violation, thus belonging either to the (1,2)_1/2 or to the (8,2)_1/2 representation of SU(3)xSU(2)xU(1). After the inclusion of the QCD corrections, the prediction for R_b becomes practically insensitive to the choice of renormalization scheme for the top mass, which for the type-I and type-II models translates in a more robust lower bound on tan(beta). The QCD-corrected determinations of Rb and BR(B->Xs gamma) are used to discuss the constraints on the couplings of a (colored) charged Higgs boson to top and bottom quarks.

Comments: 19 pages, 7 figures. v2: version published in Phys. Rev. D, with additional reference and note