Improved measurements of the B0 and B+ meson lifetimes

Updated measurements of the B0 and B+ meson lifetimes are presented. From a data sample of 1.72 million hadronic Z0 decays recorded during the period 1991 to 1993, a sample of approximately 1000 semileptonic B meson decays containing a D0, D+ or D*+ has been isolated. From the distribution of decay times in the different samples the lifetimes of the B0 and B+ mesons are determined to be 1.53 ± 0.12 ± 0.08 ps and 1.52 ± 0.14 ± 0.09 ps, respectively, where the first error is statistical and the second systematic. The ratio of the B+ to B0 lifetimes is measured to be 0.99 ± 0.14+0.05-0.04, confirming expectations that the lifetimes are similar. (orig.)