First evidence of a structure in the J/ψΛ invariant mass distribution is obtained from an amplitude analysis of Ξb-→J/ψΛK- decays. The observed structure is consistent with being due to a charmonium pentaquark with strangeness with a significance of 3.1σ including systematic uncertainties and look-elsewhere effect. Its mass and width are determined to be 4458.8±2.9-1.1+4.7MeV and 17.3±6.5-5.7+8.0MeV, respectively, where the quoted uncertainties are statistical and systematic. The structure is also consistent with being due to two resonances. In addition, the narrow excited Ξ- states, Ξ1690- and Ξ1820-, are seen for the first time in a Ξb- decay, and their masses and widths are measured with improved precision. The analysis is performed using pp collision data corresponding to a total integrated luminosity of 9 fb-1, collected with the LHCb experiment at centre-of-mass energies of 7, 8 and 13 TeV.
Aaij, R., Abellan Beteta, C., Ackernley, T., Adeva, B., Adinolfi, M., Afsharnia, H., et al. (2021). Evidence of a J/ψΛ structure and observation of excited Ξ- states in the Ξb-→J/ψΛK- decay. SCIENCE BULLETIN, 66(13), 1278-1287 [10.1016/j.scib.2021.02.030].
Evidence of a J/ψΛ structure and observation of excited Ξ- states in the Ξb-→J/ψΛK- decay
Borsato M.;Calvi M.Membro del Collaboration Group
;Capelli S.Membro del Collaboration Group
;Carniti P.Membro del Collaboration Group
;Fazzini D.Membro del Collaboration Group
;Garcia Pardinas J.Membro del Collaboration Group
;Gotti C.Membro del Collaboration Group
;Martinazzoli L.Membro del Collaboration Group
;Martinelli M.Membro del Collaboration Group
;Matteuzzi C.Membro del Collaboration Group
;Meloni S.Membro del Collaboration Group
;Petruzzo M.;Shields E. B.Membro del Collaboration Group
;
2021
Abstract
First evidence of a structure in the J/ψΛ invariant mass distribution is obtained from an amplitude analysis of Ξb-→J/ψΛK- decays. The observed structure is consistent with being due to a charmonium pentaquark with strangeness with a significance of 3.1σ including systematic uncertainties and look-elsewhere effect. Its mass and width are determined to be 4458.8±2.9-1.1+4.7MeV and 17.3±6.5-5.7+8.0MeV, respectively, where the quoted uncertainties are statistical and systematic. The structure is also consistent with being due to two resonances. In addition, the narrow excited Ξ- states, Ξ1690- and Ξ1820-, are seen for the first time in a Ξb- decay, and their masses and widths are measured with improved precision. The analysis is performed using pp collision data corresponding to a total integrated luminosity of 9 fb-1, collected with the LHCb experiment at centre-of-mass energies of 7, 8 and 13 TeV.
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