Aaron S. Chou for the Sld Collaboration

We present recent measurements by SLD of the branching fractions of B hadrons to states with 0 and 2 open charm hadrons, BR 0D and BR 2D , from which both the average charm yield per B decay, N c and the inclusive branching ratio into rare modes not containing any charmed hadrons, BR rare can be derived. We also present a new measurement of the B d mixing frequency ∆m d and limits on the B s mixing frequency ∆m s. These analyses take advantage of the excellent vertexing resolution of the VXD3, a pixel-based CCD vertex detector, which enables the topological separation of the B and cascade D decay vertices. This measurement is motivated by the possible discrepancy between measurements and Standard Model predictions of the B semileptonic branching fraction and the average charm quark/antiquark yield per B decay, N c. Recent next-to-leading-order calculations 1 agree with experiment only at rather low renormalization scales where it is not obvious that the perturbation series is nearing convergence. See Yamamoto 2 for a discussion. A true discrepancy between the measurements and the Standard Model predictions could signal either a breakdown of standard calculational techniques, or an enhancement of the rate of decays into rare or unexpected new modes. In this paper, we present measurements using a novel vertexing technique, of the branching ratios of B hadron decays into final states with 0 or 2 weakly decaying charmed hadrons. These decay categories will be referred to as 0D decays and 2D decays in which D refers to any of D 0 /D ± /D 0 s /c-baryon. The sample of B hadrons used is the B ± /B 0 /B 0 s /b−baryon admixture produced in decays of the Z 0. The measurements of BR 0D and BR 2D may be combined with previous measurements 3 of the B decay branching ratio into final states including charmonium, BR c¯ c to get a experimental value for N c using: