Research Papers in Physics and Astronomy


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Published in PHYSICAL REVIEW LETTERS 101, 232002 (2008). Copyright © 2008 The American Physical Society. Used by permission.


We report the observation of the doubly strange b baryon Ωb- in the decay channel Ωb-J/ψΩ-, with J/ψ → μ+μ- and Ω- → ΛK- → (pπ-)K-, in pp collisions at √s = 1.96 TeV. Using approximately 1.3 fb-1 of data collected with the D0 detector at the Fermilab Tevatron Collider, we observe 17:8 ± 4.9(stat) ± 0.8(syst) Ωb- signal events at a mass of 6.165 ± 0.010(stat) ± 0.013(syst) GeV. The significance of the observed signal is 5.4 σ, corresponding to a probability of 6.7 x 10-8 of it arising from a background fluctuation.

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