Observation of the $\Omega_b^-$ and Measurement of the Properties of the $\Xi_b^-$ and $\Omega_b^-$

We report the observation of the bottom, doubly-strange baryon $\Omega^-_b$ through the decay chain $\Omega^-_b \rightarrow J/\psi \, \Omega^-$, where $J/\psi \rightarrow \mu^+\, \mu^-$, $\Omega^- \rightarrow \Lambda \, K^-$, and $\Lambda \rightarrow p \, \pi^-$, using 4.2 fb$^{-1}$ of data from $p\bar p$ collisions at $\sqrt{s}=1.96$ TeV, and recorded with the Collider Detector at Fermilab. A signal is observed whose probability of arising from a background fluctuation is $4.0 \times 10^{-8}$, or 5.5 Gaussian standard deviations. The $\Omega^-_b$ mass is measured to be $6054.4\pm 6.8 (\textrm{stat.})\pm 0.9 (\textrm{syst.})$ MeV/$c^2$. The lifetime of the $\Omega^-_b$ baryon is measured to be $1.13^{+0.53}_{-0.40}(\textrm{stat.})\pm0.02(\textrm{syst.})$ ps. In addition, for the $\Xi^-_b$ baryon we measure a mass of $5790.9\pm2.6(\textrm{stat.})\pm0.8(\textrm{syst.})$ MeV/$c^2$ and a lifetime of $1.56^{+0.27}_{-0.25}(\textrm{stat.})\pm0.02(\textrm{syst.})$ ps. %These measurements were performed using 4.2 fb$^{-1}$ of %data from $p\bar p$ collisions at $\sqrt{s}=1.96$ TeV, and %recorded with the Collider Detector at Fermilab. Under the assumption that the $\Xi_b^-$ and $\Omega_b^-$ are produced with similar kinematic distributions to the $\Lambda^0_b$ baryon, we find $\frac{\sigma(\Xi_b^-){\cal B}(\Xi_b^- \rightarrow J/\psi \, \Xi^-)} {\sigma(\Lambda^0_b){\cal B}(\Lambda^0_b \rightarrow J/\psi \, \Lambda)} = 0.167^{+0.037}_{-0.025}(\textrm{stat.})\pm0.012(\textrm{syst.})$ and $\frac{\sigma(\Omega_b^-){\cal B}(\Omega_b^- \rightarrow J/\psi \, \Omega^-)} {\sigma(\Lambda^0_b){\cal B}(\Lambda^0_b \rightarrow J/\psi \, \Lambda)} = 0.045^{+0.017}_{-0.012}(\textrm{stat.})\pm0.004(\textrm{syst.})$ for baryons produced with transverse momentum in the range of $6 \, - \, 20$ GeV/$c$.