The lifetimes of the (B) over bar (0) and B- mesons are measured using a sa
mple of about four million hadronic Z decays collected from 1991 to 1995 wi
th the ALEPH detector at LEP. The data sample has been recently reprocessed
, achieving a substantial improvement in the tracking performance. Semilept
onic decays of (B) over bar (0) and B- mesons are partially reconstructed b
y identifying events containing a lepton with an associated D*(+) or D-0 me
son, The proper time of the B meson is estimated from the measured decay le
ngth and the momentum of the D-lepton system. A fit to the proper time of 1
880 D*(+)l(-) and 2856 D(0)l(-) candidates yields the following results: ta
u ((B) over bar0) = 1.518 +/- 0.053 +/- 0.034 ps, tau (B-) = 1.648 +/- 0.04
9 +/- 0.035 ps, tau (B-)/tau ((B) over bar0) = 1.085 +/- 0.059 +/- 0.018. (
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