2021/02/08 by CMS Collaboration · 1 voice · 1 citation
Physics and Astronomy · #hep-ex
paper · pdf · doi:10.1103/physrevlett.126.252003
published as Phys. Rev. Lett. 126, 252003 (2021) · Replaced with the published version. Added the journal reference and the DOI. All the figures and tables can be found at http://cms-results.web.cern.ch/cms-results/public-results/publications/BPH-20-004 (CMS Public Pages)
arxiv published 2021/02/08 · arxiv created 2021/06/25 · arxiv updated 2021/06/30
The Ξ-b π+ π- invariant mass spectrum is investigated with an event sample of proton-proton collisions at √(s) = 13 TeV, collected by the CMS experiment at the LHC in 2016-2018 and corresponding to an integrated luminosity of 140 fb-1. The ground state Ξ-b is reconstructed via its decays to J/ψ Ξ- and J/ψ Ξ- Λ K-. A narrow resonance, labeled Ξb(6100)-, is observed at a Ξ-b π+ π- invariant mass of 6100.3 ± 0.2 (stat) ± 0.1 (syst) ± 0.6 (Ξ-b) MeV, where the last uncertainty reflects the precision of the Ξ-b baryon mass. The upper limit on the Ξb(6100)- natural width is determined to be 1.9 MeV at 95% confidence level. Following analogies with the established excited Ξc baryon states, the new Ξb(6100)- resonance and its decay sequence are consistent with the orbitally excited Ξ-b baryon, with spin and parity quantum numbers JP = 3/2-.