Lepton polarization and forward-backward asymmetries in b→sτ+τ- -: art. no. 034007

We study the spin polarizations of both tau leptons in the decay b-->stau(+)tau(-). In addition to the polarization asymmetries involving a single tau, we construct asymmetries for the case where both polarizations are simultaneously measured. We also study forward-backward asymmetries with polarized tau's. We find that a large number of asymmetries are predicted to be large, greater than or similar to10%. This permits the measurement of all Wilson coefficients and the b-quark mass, thus allowing the standard model (SM) to be exhaustively tested. Furthermore, there are many unique signals for the presence of new physics. For example, asymmetries involving triple-product correlations are predicted to be tiny within the SM, O(10(-2)). Their observation would be a clear signal of new physics.