Extended minimal flavour violating MSSM and implications for B physics

Abstract

Abstract:The recently reported measurements of the CP asymmetry a ψK by the BABAR and BELLE collaborations are in good agreement with the standard model prediction. With the anticipated precision in a ψK at the B factories and hadron colliders, one hopes to pin down any possible deviation from the SM. We discuss an extension of the MFV-supersymmetric models which comfortably accommodates the current measurements of the CP asymmetry a ψK , but differs from the SM due to an additional flavour changing structure beyond the CKM matrix. We analyze the compatibility of this model with present data and suggest specific tests in forthcoming experiments in B physics. In addition to the CP-asymmetries in B-meson decays and the B 0 s -B 0 s mass difference, we emphasize measurements of the radiative transition b → dγ as sensitive probes of the postulated flavour changing structure. Interestingly, the CKM-unitarity analysis in these models also allows solutions with γ > π/2, where γ = − arg V ub . Such large values of γ are hinted by the current measurements of the branchig ratios for the decays B → ππ and B → Kπ. Outline of the modelThis talk is based on the paper in Ref. [1]. The supersymmetric model that we consider is essentially based on the assumptions of heavy squarks (of the first two generations) and gluinos. The charged Higgs and the lightest chargino and stop masses are required to be heavier than 100 GeV in order to satisfy the lower bounds from direct searches. The rest of the SUSY spectrum is assumed to be almost degenerate and heavier than 1 TeV. In this framework the lightest stop is almost right-handed and the stop mixing angle (which parameterizes the amount of the left-handed stopt L present in the lighter mass eigenstate) turns out to be of order O(M W /Mq) 10%; for definiteness we will take |θt| ≤ π/10.The assumption of a heavy gluino totally suppresses any possible gluino-mediated SUSY contribution to low energy observables. On the other hand, the presence of only a * Speaker.† E.L. acknowledges financial support from the Alexander Von Humboldt Foundation.