Observation of Two New Ξ_{b}^{-} Baryon Resonances (original) (raw)

Two structures are observed close to the kinematic threshold in the Ξ_{b}^{0}π^{-} mass spectrum in a sample of proton-proton collision data, corresponding to an integrated luminosity of 3.0 fb^{-1}, recorded by the LHCb experiment. In the quark model, two baryonic resonances with quark content bds are expected in this mass region: the spin-parity J^{P}=(1/2)^{+} and J^{P}=(3/2)^{+} states, denoted Ξ_{b}^{'-} and Ξ_{b}^{*-}. Interpreting the structures as these resonances, we measure the mass differences and the width of the heavier state to be…