Observation of the Ωb- baryon and measurement of the properties of the Ξb- and Ωb- baryons

We report the observation of the bottom, doubly-strange baryon Ω_b^- through the decay chain Ω_b^-→J/ψΩ^-, where J/ψ→μ⁺μ^-, Ω^-→ΛK^-, and Λ→pπ^-, using 4.2fb^-1 of data from pp¯ collisions at s=1.96TeV, and recorded with the Collider Detector at Fermilab. A signal is observed whose probability of arising from a background fluctuation is 4.0×10^-8, or 5.5 Gaussian standard deviations. The Ω_b^- mass is measured to be 6054.4±6.8(stat)±0.9(syst)MeV/c². The lifetime of the Ω_b^- baryon is measured to be 1.13_-0.40^+0.53(stat)±0.02(syst)ps. In addition, for the Ξ_b^- baryon we measure a mass of 5790.9±2.6(stat)±0.8(syst)MeV/c² and a lifetime of 1.56_-0.25^+0.27(stat)±0.02(syst)ps. Under the assumption that the Ξ_b^- and Ω_b^- are produced with similar kinematic distributions to the Λ_b⁰ baryon, we find (σ(Ξ_b^-)B(Ξ_b^-→J/ψΞ^-))/(σ(Λ_b⁰)B(Λ_b⁰→J/ψΛ))=0.167_-0.025^+0.037(stat)±0.012(syst) and (σ(Ω_b^-)B(Ω_b^-→J/ψΩ^-))/(σ(Λ_b⁰)B(Λ_b⁰→J/ψΛ))=0.045_-0.012^+0.017(stat)±0.004(syst) for baryons produced with transverse momentum in the range of 6-20GeV/c.