The lifetime of the $B_s^0$ meson is measured using the exclusive decay mode $B_s^0\to J/\psi \phi$, where $J/\psi \to {\mu }^{+}{\mu }^{-}$ and $\phi \to K^{+}{K}^{-}$. The data sample consists of $110{\mathrm{pb}}^{-1\mathrm{}}$ of $p\overline{p}$ collisions at $\sqrt{s}=1.8\mathrm{TeV}$, collected by the CDF detector at the Fermilab Tevatron collider during 1992–1995. We find $58\pm 12$ signal events, and the $B_s^0$ meson lifetime is determined to be ${\tau }_{B_s^0}{=1.34\mathrm{}}_{-0.19\mathrm{}}^{+0.23\mathrm{}}\left(\mathrm{stat}\right)\pm 0.05\left(\mathrm{syst}\right)$ ps. This result is consistent with previous measurements of the $B_s^0$, $B^{+}$, and $B_d^0$ meson lifetimes and with theoretical predictions.

• Received 1 May 1996

DOI:https://doi.org/10.1103/PhysRevLett.77.1945