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The Z -> bb decay asymmetry and flavor changing neutral currents

Michael S. Chanowitz

hep-pharXiv:hep-ph/9905478

Abstract

The measured value of Ab, the Z bb asymmetry parameter, disagrees with the Standard Model at 99% confidence level. If genuine the discrepancy could indicate new interactions unique to third generation quarks, implying enhanced Z penguin amplitudes. Enhanced rates are predicted for rare K and B decays, such as K+ --> pi+ nu nu, KL --> pi0 nu nu, B --> Xs nu nu, and Bs --> mu mu. Measurements of epsilon/epsilon then imply QCD penguin amplitudes must also be similarly enhanced. The Higgs sector of an SU(2)L x SU(2)R gauge theory has some of the features needed to explain these phenomena and would also imply right-handed penguin amplitudes.

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