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

TL;DR

This paper develops resummation formulae for tan-beta-enhanced loop corrections in the MSSM beyond the decoupling limit, revealing new FCNC effects and providing tools for phenomenological analysis of B meson processes.

Contribution

It derives new resummation formulas for tan-beta-enhanced corrections applicable beyond the decoupling limit, including novel FCNC couplings and phenomenological implications.

Findings

Resummation formulas valid beyond the decoupling limit.

Identification of new FCNC effects involving gluinos and neutralinos.

Impact on B meson CP asymmetries and mixing phases.

Abstract

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 Delta_b. 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 C_8, 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 B_d -> phi K_S. We further quote formulae for B_s -> mu^+ mu^- and B_s-B_s-bar mixing valid beyond the decoupling limit and find a new contribution affecting the phase of the B_s-B_s-bar mixing amplitude. Our resummed tan-beta-enhanced effects are cast into Feynman rules permitting an easy implementation in automatic calculations.