Preliminary Measurements of B “ and B + Lifetimes at SLD 1 The SLD

The Efetimes of B " and B+ mesons have been measured using a sample of 150,000 hadronic 20's co~ected by the SLD experiment at the SLC between 1993 and 1995. Two analyses are presented. The first identifies semileptonic decays of B mesons with high (p, pt) leptons and reconstructs the B meson decay length and charge by vertexing the lepton with a partially reconstructed D meson. 428 (549) neutral (charged) decays Hkehhood fit procedure finds: TBO = 1.603~:~~(stat) 7B~ = 1.49~~:~~(stat) This method results in a sample of with high charge + O.lo(syst) ps, + o.05(syst) ps, + o.07(syst). purity. A maximum The second analysis isolates a sample of B meson decays with a 2-D impact parameter tag and reconstructs the decay length and charge using a novel topological vertex reconstruction method. This results in a high statistics sample of 3382 (5303) neutral (charged) decays with good charge purity. A maximum likelihood fit procedure finds: TBO = 1.55 + 0.07(stat) + 0.12(syst) ps, 7Bt = 1.67 + 0.06(stat) + 0.09(syst) ps, TBt /TBO = 1.08~~:~~(stat) + O.10(syst).