engleski

Observation of a New Excited Beauty Strange Baryon Decaying to Ξ−bπ+π−

The Ξ−bπ+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/ψΞ− and J/ψΛK−. A narrow resonance, labeled Ξb(6100)−, is observed at a Ξ−bπ+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. The low Ξb(6100)− signal yield observed in data does not allow a measurement of the quantum numbers of the new state. However, 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−

High energy physics ; Experimental particle physics ; LHC ; CMS ; Radiation-hard detectors ; Si microstrip and pad detectors ; Radiation damage to detector materials (solid state) ; Particle tracking detectors (Solid-state detectors) ; radiation: damage ; CMS: upgrade ; tracking detector ; semiconductor detector: design ; semiconductor detector: microstrip ; performance ; Hadron-Hadron scattering (experiments) ; Top physics ; p p: scattering ; p p: colliding beams ; top: single production

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