Lifetime and oscillations of B-s(0) mesons have been studied in events with
a large transverse momentum lepton and a D-s of opposite electric charge i
n the same hemisphere, selected from about 3.6 million hadronic Z(0) decays
accumulated by DELPHI between 1992 and 1995.
The B-s(0) lifetime and the fractional width difference between the two phy
sical B-s(0) states have been found to be:
tau(Bs0) = (1.42(-0.13)(+0.14)(stat.) +/- 0.03(syst)) ps
Delta Gamma(Bs0) /Gamma(Bs0) < 0.46 at the 95% C.L.
In the latter result it has been assumed that tau(Bs0) = tau(Bd0).
Using the same sample, a limit on the mass difference between the physical
B-s(0) states has been set:
Delta m(Bs0) > 7.4 ps(-1) at the 95% C.L.
with a corresponding sensitivity equal to 8.1 ps(-1).