Determination of Spin-Parity Quantum Numbers for the Narrow Structure near the p Λ ˉ Threshold in e+e- →pK- Λ ˉ + c. c.

作者：Ablikim, M.; Achasov, M.N.; Adlarson, P.; Aliberti, R.; Amoroso, A.; An, M.R.; An, Q.; Bai, Y.; Bakina, O.; Balossino, I.; Ban, Y.; Batozskaya, V.; Begzsuren, K.; Berger, N.; Berlowski, M.; Bertani, M.; Bettoni, D.; Bianchi, F.; Bianco, E.; Bloms, J.; Bortone, A.; Boyko, I.; Briere, R.A.; Brueggemann, A.; Cai, H.; Cai, X.; Calcaterra, A.; Cao, G.F.; Cao, N.; Cetin, S.A.; Chang, J.F.; Chang, T.T.; Chang, W.L.; Che, G.R.; Chelkov, G.; Chen, C.; Chen, Chao; Chen, G.; Chen, H.S.; Chen, M.L.

来源：Physical Review Letters, 2023, 131(15): 151901.

DOI：10.1103/PhysRevLett.131.151901

• Amplitude analysis
• Center-of-mass energies
• Centre-of-mass energies
• Data sample
• Integrated luminosity
• Quantum numbers
• Statistical significance
• Uncertainty

A narrow structure in the pΛˉ system near the mass threshold, named as X(2085), is observed in the process e+e-→pK-Λˉ with a statistical significance greater than 20σ. Its spin and parity are determined for the first time to be JP=1+ in an amplitude analysis, with a statistical significance greater than 5σ over other quantum numbers (0-,1- and 2+). The pole positions of X(2085) are measured to be Mpole=(2084-2+4±9) MeV and Γpole=(58-3+4±25) MeV, where the first uncertainties are statistical and the second ones are systematic. The analysis is based on the study of the process e+e-→pK-Λˉ and uses the data samples collected with the BESIII detector at the center-of-mass energies s=4.008, 4.178, 4.226, 4.258, 4.416, and 4.682 GeV with a total integrated luminosity of 8.35 fb-1.
? 2023 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the "https://creativecommons.org/licenses/by/4.0/"Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP3.