Resummation of tan-beta-enhanced supersymmetric loop corrections beyond the decoupling limit

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We study the Minimal Supersymmetric Standard Model with Minimal Flavour Violation for the case of a large parameter tanbeta and arbitrary values of the supersymmetric mass parameters. We derive several resummation formulae for tanbeta-enhanced loop corrections, which were previously only known in the limit of supersymmetric masses far above the electroweak scale. Studying first the renormalisation-scheme dependence of the resummation formula for the bottom Yukawa coupling, we clarify the use of the sbottom mixing angle in the supersymmetric loop factor Deltab. As a new feature, we find tan-beta-enhanced loop-induced flavour-changing neutral current (FCNC) couplings of gluinos and neutralinos which in turn give rise to new effects in the renormalisation of the Cabibbo-Kobayashi-Maskawa matrix and in FCNC processes of B mesons. For the chromomagnetic Wilson coefficient C₈, these gluino-squark loops can be of the same size as the known chargino-squark contribution. We discuss the phenomenological consequences for the mixing-induced CP asymmetry in Bd -> phi Kₛ. We further quote formulae for Bₛ -> mu+ mu- and Bₛ-Bₛ-bar mixing valid beyond the decoupling limit and find a new contribution affecting the phase of the Bₛ-Bₛ-bar mixing amplitude. Our resummed tan-beta-enhanced effects are cast into Feynman rules permitting an easy implementation in automatic calculations.