D. Buskulic et al., MEASUREMENT OF THE B-S(0) LIFETIME AND PRODUCTION-RATE WITH D-S(-)L(-DECAYS() COMBINATIONS IN Z), Physics letters. Section B, 361(1-4), 1995, pp. 221-233
The lifetime of the B-s(0) meson is measured in approximately 3 millio
n hadronic Z decays accumulated using the ALEPH detector at LEP from 1
991 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 selec
tion criteria designed to ensure precise proper time reconstruction an
d 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) %.