Threshold corrections to m_b and the bb̄ → H _i⁰ production in CP-violating SUSY scenarios

The inclusion of supersymmetric threshold corrections to the b-quark mass has dramatic consequences in scenarios with large CP-mixing effects in the Higgs sector. In particular, when the phase of the combination M _g̃μ is ∼180°±30°, the lightest sbottom squark becomes tachyonic and, possibly, the b-quark Yukawa coupling nonperturbative for values of tanβ ranging from intermediate up to large or very large, depending on the size of arg(A_tμ), arg(A _bμ), and the details of the spectrum. For these scenarios, when allowed, as well as scenarios with different values of arg(M _g̃μ), the cross sections for the production of the three neutral Higgs bosons through b-quark fusion have interesting dependences on arg(A_tμ) and arg(A_bμ), and the deviations induced by the m_b corrections are rather large. In general, such production channel cannot be neglected with respect to the production through gluon fusion. For large CP-mixing effects, the lightest neutral Higgs boson can be mainly CP odd and the b-quark fusion becomes its main production mechanism. Searches at the Tevatron and the LHC can easily detect such a Higgs boson, or constrain the CP-violating scenarios that allow it.