Measurements of the B(S)(0) and Lambda(0)(b) lifetimes

This paper presents updated measurements of the lifetimes of the B-s(0) meson and the Lambda(b)(0) baryon using 4.4 million hadronic Z(0) decays recorded by the OPAL detector at LEP from 1990 to 1995. A sample of Bg decays is obtained using D(s)(-)l(+) combinations, where the D-s(-) is fully reconstructed in the phi pi(-), (KK-)-K-*0 and (K-KS0) decay channels and partially reconstructed in the phi l(-) X decay mode. A sample of Lambda(b)(0) decays is obtained using Lambda(c)(+)l(-) combinations, where the Lambda(c)(+)is fully reconstructed in its decay to a pK(-)pi(+) final state and partially reconstructed in the Lambda l(+)nu X decay channel, From 172 +/- 28 D(s)(-)l(+) combinations attributed to B-s(0) decays, the measured lifetime is tau(B-s(0))= 1.50(-0.15)(+0.16)+/- 0.04ps, where the errors are statistical and systematic, respectively. From the 129 +/- 25 Lambda(c)(+)l(-) combinations attributed to Lambda(b)(0) decays, the measured lifetime is tau(Lambda(b)(0))= 1.29(-0.22)(+0.24) +/- 0.06ps, where the erroers are statistical and systematic, respectively. (C) 1998 Published by Elsevier Science B.V. All rights reserved.