First Observation of Excited Ω_{b}^{-} States

We report four narrow peaks in the Ξ_{b}^{0}K^{-} mass spectrum obtained using pp collisions at center-of-mass energies of 7, 8, and 13 TeV, corresponding to a total integrated luminosity of 9 fb^{-1} recorded by the LHCb experiment. Referring to these states by their mass, the mass values are m[Ω_{b}(6316)^{-}]=6315.64±0.31±0.07±0.50 MeV, m[Ω_{b}(6330)^{-}]=6330.30±0.28±0.07±0.50 MeV, m[Ω_{b}(6340)^{-}]=6339.71±0.26±0.05±0.50 MeV, m[Ω_{b}(6350)^{-}]=6349.88±0.35±0.05±0.50 MeV, where the uncertainties are statistical, systematic, and the last is due to the knowledge of the Ξ_{b}^{0} mass. The natural widths of the three lower mass states are consistent with zero, and the 90% confidence-level upper limits are determined to be Γ[Ω_{b}(6316)^{-}]