Semileptonic branching fraction and hadronic width of the B mesons in light of the new CLEO observation of b → DX

This talk reports the latest CLEO observation of D production in b decays, which provides new insight of the QCD interactions in heavy quark systems. The observed B semileptonic branching fraction has been significantly lower than QCD expectations, as was confirmed by recent lepton-lepton correlation studies at various experiments that removed most of the model dependence in previous generation measurements. One possible explanation to accommodate this lepton shortage or a wider hadronic width of B mesons is that the process b → ccs contributes at a higher rate than expected. That explanation, however, predicts more charm production than is observed. Using lepton tags in B events this analysis measures the fraction of b → DX in addition to b → DX. The first observation of B → DDX has profound implications to both experiment and theory. (orig.)