Measurement of the B{sup +} and B{sup 0} lifetimes from semileptonic decays at SLD

The lifetimes of B{sup +} and B{sup 0} mesons have been measured using a sample of 150,000 hadronic Z{sup 0} decays collected by the SLD experiment at the SLC between 1993 and 1995. The analysis identifies the semileptonic decays of B mesons with high (p,p{sub t}) leptons and reconstructs the B meson decay length and charge by vertexing the lepton with a partially reconstructed D meson. This method results in a sample of 634 (584) charged (neutral) decays with high charge purity. A maximum likelihood fit finds: {tau}{sub B{sup +}} = 1.60{sub {minus}0.11}{sup +0.12}(stat) {+-} 0.06(syst) ps, {tau}{sub B{sup 0}} = 1.55{sub {minus}0.12}{sup +0.13}(stat) {+-} 0.09(syst) ps, and the ratio {tau}{sub B{sup +}}/{tau}{sub B{sup 0}} = 1.03{sub {minus}0.13}{sup +0.15}(stat) {+-} 0.08(syst)