Evidence of a J/ψΛ structure and observation of excited Ξ- states in the Ξb-→J/ψΛK- decay

LHCb Collaboration, 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), pp. 1278-1287. (doi: 10.1016/j.scib.2021.02.030)

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.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Alexander, Dr Michael and Schiller, Dr Manuel and Coombs, George and Spradlin, Dr Patrick and Douglas, Lauren and Seman Bobulska, Dana and Soler, Professor Paul and Friday, David and Traill, Mr Murdo and Eklund, Prof Lars and Longstaff, Iain Richard
• Authors: LHCb Collaboration, , Alexander, M., Bobulska, D., Coombs, G., Douglas, L., Eklund, L., Friday, D. A., Longstaff, I., Schiller, M., Soler, F.J.P., Spradlin, P., and Traill, M.
• College/School: College of Science and Engineering > School of Physics and Astronomy
• Journal Name: Science Bulletin
• Publisher: Elsevier
• ISSN: 2095-9273
• ISSN (Online): 2095-9281
• Published Online: 09 March 2021
• Copyright Holders: Copyright © 2021 Science China Press
• First Published: First published in Science Bulletin 66(13): 1278-1287
• Publisher Policy: Reproduced under a Creative Commons License