Study of B-s(0)-(B-s(0))over-bar oscillations and B-s(0) lifetimes using hadronic decays of B-s(0) mesons

Oscillations of B-s(0) mesons have been studied in samples selected from about 3.5 million hadronic Z decays detected by DELPHI between 1992 and 1995. One analysis uses events in the exclusive decay channels: B-s(0) --> D(s)(-)pi (+) or D(s)(-)a(1)(+) and B-s(0) --> (D) over bar (0)K(-)pi (+) or (D) over bar (0)K(-)a(1)(+), where D decays are completely reconstructed. In addition, B-s(0)-(B) over bar (0)(s) oscillations have been studied in events with an exclusively reconstructed D, accompanied in the same hemisphere by a high momentum hadron of opposite charge. Combining the two analyses, a limit on the mass difference between the physical B-s(0) states has been obtained: Deltam(Bs0) > 4.0 ps(-1) at the 95% C.L. with a sensitivity of Deltam(Bs0) = 3.2 ps(-1) Using the latter sample of events, the B-s(0) lifetime has been measured and an upper limit on the decay width difference between the two physical B-s(0) states has been obtained: tau (Bs0) = 1.53(-0.15)(+0.16)(stat.) +/- 0.07(syst.) ps Delta Gamma (Bs0)/Gamma (Bs0) < 0.69 at the 95% C.L. The combination of these results with those obtained using D(s)(+/-)l(+/-) sample gives: Deltam(Bs0) > 4.9 ps(-1) at the 95% C.L. with a sensitivity of Deltam(Bs0) = 8.7 ps(-1) tau (Bs0) = 1.46 +/- 0.11 ps and Delta Gamma (Bs0)/Gamma (Bs0) < 0.45 at the 95% C.L.