BUSKULIC, D (reprint author), INST NATL PHYS NUCL & PHYS PARTICULES, CNRS, PHYS PARTICULES LAB, F-74019 ANNECY LE VIEUX, FRANCE.
The lifetime of the B-s(0) meson is measured in approximately 3 million hadronic Z decays accumulated using the ALEPH detector at LEP from 1991 to 1994. Seven different D-s(-) decay modes were reconstructed and combined with an opposite sign lepton as evidence of semileptonic B-s(0) decays. Two hundred and eight D(s)(-)l(+) candidates satisfy selection criteria designed to ensure precise proper time reconstruction and yield a measured B-s(0) lifetime of tau(B-s(0)) = 1.59(-0.15)(+0.17) (stat) +/-0.03 (syst) ps. Using a larger, less constrained sample of events, the product branching ratio is measured to be Br((b) over bar --> B-s(0)) . Br(B-s(0) --> D(s)(-)l(+)nu X) = 0.82 +/- 0.09 (stat)(-0.14)(+0.13) (syst) %.