Measurement of the Bs0 Meson Lifetime Using Semileptonic Decays
  The lifetime of the Bs0 meson is measured using the semileptonic decay Bs0 --> Ds- l+ nu X. The data sample consists of about 110 pb^-1 of pp= collisions at sqrt{s} = 1.8 TeV collected by the CDF detector at Fermilab. Four different Ds- decay modes are reconstructed resulting in approximately 600 Ds-l+ signal events. The Bs0 meson lifetime is determined to be tau(Bs0) = (1.36 +- 0.09 +0.06-0.05) ps, where the first and second uncertainties are statistical and systematic, respectively. The Bs0 meson decay length distribution is examined for a lifetime difference Delta_Gamma/Gamma between the two mass eigenstates of the Bs0 meson. An upper limit of Delta_Gamma/Gamma < 0.83 is set at 95% confidence level. 
F. Abe, et al. (The CDF Collaboration)