Measurement of the lifetime of the B(S)(0) meson and the width difference in the B(S)(0)-(bar)B(S)(0) system in proton-antiproton collisions at 1.8 TeV.

Abstract

This dissertation presents a measurement of the lifetime of the $B\sbsp{S}{0}$ meson, using data from 110 $pb\sp{-1}$ of $p\bar p$ collisions at $\sqrt{s}=1.8$ TeV, collected with the Collider Detector at Fermilab between August 1992 and February 1996. The $B\sbsp{S}{0}$ meson is reconstructed in the semileptonic decay $B\sbsp{S}{0}\to D\sbsp{S}{-}\ell\sp+\nu X,$ where the $D\sbsp{S}{-}$ meson is reconstructed in the decays $D\sbsp{S}{-}\to\phi\pi\sp-, D\sbsp{S}{-}\to K\sp{*0}K\sp-,$ and $D\sbsp{S}{-}\to K\sbsp{s}{0}K\sp-,$ yielding a total sample of approximately 400 $D\sbsp{S}{-}\ell\sp+$ events. The $B\sbsp{S}{0}$ meson lifetime is measured to be $\tau(B\sbsp{S}{0})=1.42\ \sbsp{-0.11}{+0.12}(stat.)\pm0.03(syst.)$ ps. The proper lifetime distribution of $B\sbsp{S}{0}$ candidates is examined for a difference in the decay widths, $\Delta\Gamma,$ of the two CP eigenstates of the $B\sbsp{S}{0}$ meson, $B\sbsp{S}{H}$ and $B\sbsp{S}{L}.$ An upper limit on the width difference at 95% confidence level is measured to be ${\Delta\Gamma\over \Gamma}<0.83.$ This is used to determine a limit on the mixing parameter $x\sb{S}=\Delta m\sb{s}/\Gamma<148\cdot\left({5.6\times10\sp{-3}\over \Delta\Gamma/\Delta m}\right)$ and the limit $\Delta m\sb{s}<94$ ps$\sp{-1}\cdot\left({5.6\times10\sp{-3}\over\Delta\Gamma/\Delta m}\right)\cdot\left({1.57\ ps\over\tau(B\sbsp{S}{0})}\right).$