From a New Smell to a New Flavour

Using the preliminary data on Bd-Bd mixing from ARGUS, and the standard model with three families, we infer a lower bound on the top quark mass of 50-70 GeV; also, Bs-B~ mixing has to be close to maximal. We discuss how the prospects for observing CP violation in B ° decays are enhanced and sketch alternative scenarios for new physics. 1. Introduction Almost from the inception orB physics it was realized that dedicated research in this field had the potential to be as revealing (if not more so) as K physics. These expectations were based on rather general qualitative arguments; experimental information obtained in the meantime has actually strengthened these arguments: the "long" lifetime r(B)~ 1 ps; m(top)>22 GeV; the intriguing evidence for B°-13 ° mixing presented by UAI [ 1 ]. Most recently the ARGUS Collaboration has found evidence for surprisingly strong Bd-I3d mixing. Their preliminary results on di-leptons observed in e+e ~]'(4s)~BB read [2]