Measurement of the B0 and B+ lifetimes

Abstract From a data sample of approximately 240 000 hadronicZ 0 decays recorded during 1991 a sample of about 130 semileptonic B hadrondecays containing a D 0 , D + or D ∗+ has been isolated. Using silicon microvertex detector information the decay vertices in these events have been reconstructed. The average B hadronlifetime of the mix of B hadronsin this event sample is measured to be 1.51 −0.14 +0.16 ±0.11 ps. From the distribution of decay times in the different samples the lifetimes of the B 0 and B+ mesonsare determined to be 1.51 −0.23−0.14 +0.24+0.12 ps and 1.51 −0.28−0.14 +0.30+0.12 ps, respectively. The measured ratio of the B + to B 0 lifetimes of 1.00 −0.25 +0.33 ±0.08 supports expectations that the lifetimes are similar.