Measurement of the mass and lifetime of the ${\mathrm{\Omega }}_b^{-}$ baryon

A proton-proton collision data sample, corresponding to an integrated luminosity of 3 fb${}^{-1}$ collected by LHCb at $\sqrt{s}=7$ and 8 TeV, is used to reconstruct $63\pm 9$ ${\mathrm{\Omega }}_b^{-}\to {\mathrm{\Omega }}_c^0{\pi }^{-}$, $\Omega_c^0\to pK^-K^-\pi^+$decays\mathrm{.}Usingthe$\Xi_b^-\to\Xi_c^0\pi^-$,$\Xi_c^0\to pK^-K^-\pi^+$ decay mode for calibration, the lifetime ratio and absolute lifetime of the ${\mathrm{\Omega }}_b^{-}$ baryon are measured to be \begin{align*} \frac{\tau_{\Omega_b^-}}{\tau_{\Xi_b^-}} &= 1.11\pm0.16\pm0.03, \ \tau_{\Omega_b^-} &= 1.78\pm0.26\pm0.05\pm0.06~{\rm ps}, \end{align*} where the uncertainties are statistical, systematic and from the calibration mode (for ${\tau }_{{\mathrm{\Omega }}_b^{-}}$ only). A measurement is also made of the mass difference, $m_{{\mathrm{\Omega }}_b^{-}}-m_{{\mathrm{\Xi }}_b^{-}}$, and the corresponding ${\mathrm{\Omega }}_b^{-}$ mass, which yields \begin{align*} m_{\Omega_b^-}-m_{\Xi_b^-} &= 247.4\pm3.2\pm0.5~{\rm MeV}/c^2, \ m_{\Omega_b^-} &= 6045.1\pm3.2\pm 0.5\pm0.6~{\rm MeV}/c^2. \end{align*} These results are consistent with previous measurements.