Non-diagonal flavour observables in B and Collider Physics⋆

Until now the focus within the direct search for supersymmetry has mainly been on flavour diagonal observables. Recently lepton flavour violating signals at future electron positron colliders have been studied. There is now an opportunity to analyse the relations between collider observables and lowenergy observables in the hadronic sector. In a first work in this direction, we study flavour violation in the squark decays of the second and third generations taking into account results from B physics, in particular from the rare decay b → sγ. Correlations between various squark decay modes can be used to get more precise information on various flavour violating parameters. PACS. 12.60.Jv – 13.25.Hv – 14.80.Ly 1 Sources of Flavour Violation Within the Minimal Supersymmetric Standard Model (MSSM) there are two new sources of flavour changing neutral currents (FCNC), namely new contributions which are induced through the quark mixing as in the SM and generic supersymmetric contributions through the squark mixing. In contrast to the Standard Model (SM), the structure of the unconstrained MSSM does not explain the suppression of FCNC processes that is observed in experiments; this is the essence of the well-known supersymmetric flavour problem. FCNC processes therefore yield important (indirect) information on the construction of supersymmetric extensions of the SM and can contribute to the question of which mechanism ultimately breaks supersymmetry. The experimental measurements of the rates for these processes, or the upper limits set on them, impose in general a reduction of the size of parameters in the soft supersymmetry-breaking terms [1,2,3]. To understand the sources of flavour violation that may be present in supersymmetric models, in addition to those enclosed in the CKM matrix K, one has to consider the contributions to the squark mass matrices