Measurement of the BS 0 meson lifetime using semileptonic decays

The lifetime of the B{sub S}{ sup0} mesonis measured using the semileptonic decayB{sub S}{ sup0}{r_arrow}D{sub S}{ sup{minus}}l{ sup+}{nu}X. The data sample consists of about 110 pb{ sup{minus}1} of p{bar p} collisions at {radical} (s) =1.8 TeV collected by the CDF detector at Fermilab. Four different D{sub S}{ sup{minus}} decay modes are reconstructed resulting in approximately 600 D{sub S}{ sup{minus}}l{ sup+} signal events. The B{sub S}{ sup0} mesonlifetime is determined to be {tau}(B{sub S}{ sup0})=(1.36{plus_minus}0.09{sub {minus}0.05}{ sup+0.06}) ps, where the first and second uncertainties are statistical and systematic, respectively. The B{sub S}{ sup0} mesondecay length distribution is examined for a lifetime difference {Delta}{Gamma}/{Gamma} between the two mass eigenstates of the B{sub S}{ sup0} meson. An upper limit of {Delta}{Gamma}/{Gamma}{lt}0.83 is set at the 95{percent} confidence level. {copyright} {ital 1999} {ital The American Physical Society}