Adair, A.Boulahouache, C.Ecklund, K.M.Geurts, F.J.M.Padley, B.P.Redjimi, R.Roberts, J.Zabel, J.2015-09-032015-09-032012Adair, A., Boulahouache, C., Ecklund, K.M., et al.. "Observation of a New Ξb Baryon." <i>Physical Review Letters,</i> 108, no. 25 (2012) American Physical Society: 252002. http://dx.doi.org/10.1103/PhysRevLett.108.252002.https://hdl.handle.net/1911/81620The observation of a new b baryon via its strong decay into Ξ−bπ+ (plus charge conjugates) is reported. The measurement uses a data sample of pp collisions at √s=7  TeV collected by the CMS experiment at the LHC, corresponding to an integrated luminosity of 5.3  fb−1. The known Ξ−b baryon is reconstructed via the decay chain Ξ−b→J/ψΞ−→μ+μ−Λ0π−, with Λ0→pπ−. A peak is observed in the distribution of the difference between the mass of the Ξ−bπ+ system and the sum of the masses of the Ξ−b and π+, with a significance exceeding 5 standard deviations. The mass difference of the peak is 14.84±0.74(stat)±0.28(syst)  MeV. The new state most likely corresponds to the JP=3/2+ companion of the Ξb.engThis is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Journal articlehttp://dx.doi.org/10.1103/PhysRevLett.108.252002