Observation of a new excited beauty strange baryon decaying to Ξ−bπ+π−

• Autor(a) principal: Sirunyan, A. M.
• Data de Publicação: 2021
• Outros Autores: Silveira, Gustavo Gil da, CMS Collaboration
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UFRGS
• Texto Completo: http://hdl.handle.net/10183/237185
• topic: Aceleradores de partículas; Colisões proton-proton

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−.