An improved measurement of the BS0 lifetime

Abstract This letter presents an updated measurement of the lifetime of the B s 0 meson using 3.6 million hadronic Z 0 decays recorded by the OPAL detector at LEP from 1990 to 1994. A sample of B s 0 decays is obtained using D s − l + combinations, where the D s − is reconstructed in either the φπ − or K ∗0 K − decay mode. From 79 ± 13 D x l combinations attributed to B s 0 decays in this data sample, we measure τ (B s 0 ) = 1.54 −0.21 +0.25 ± 0.06 ps, where the errors are statistical and systematic, respectively.