Refinements of the Bottom and Strange MSSM Higgs Yukawa Couplings at NNLO

Abstract

We extend the already existing two-loop calculation of the effective bottom-Yukawa coupling in the MSSM. In addition to the resummation of the dominant corrections for large values of tg${\hat{I}}^2$, we include the subleading terms related to the trilinear Higgs coupling $A_b$ and contributions induced by the electroweak gauge couplings. This calculation has been extended to the NNLO corrections to the MSSM strange-Yukawa coupling. Our analysis leads to residual theoretical uncertainties of the effective Yukawa couplings at the per-cent level.

23 pages, 9 figures, extension of the work described in arxiv:1001.1935 and arxiv:0808.0087, reference added, substantial upgrade to the full Delta_b results at NNLO