Determination of Spin-Parity Quantum Numbers for the Narrow Structure near the pΛ[over ¯] Threshold in e^{+}e^{-}→pK^{-}Λ[over ¯]+c.c

• Published in: Physical review letters 2023-10, Vol.131 (15), p.151901-151901
• Main Authors: An, M R, Begzsuren, K, Chang, J F, Chang, W L, Choi, S K, Dai, H L, Denysenko, I, Duan, Z H, Fan, Y L, Fritsch, M, Fu, C D, Gao, H, Geng, C, Gramigna, S, Guan, Z L, Hu, J F, Huang, K X, Hüsken, N, Jeong, J H, Jiang, X S, Jiao, Z, Jin, Y, Kui, X, Kappert, R, Ke, B C, Kupsc, A, Li, F, Li, J W, Li, Ke, Li, L J, Lin, T, Liu, C X, Liu, D, Liu, Lu, Liu, W K, Liu, X, Lou, X C, Lu, X L, Luo, T, Lyu, Y F, Ma, J L, Ma, X Y, Maggiora, M, Mitchell, R E, Nerling, F, Plura, S, Qian, W B, Qin, X P, Qin, Z H, Sarantsev, A, Shan, X Y, Shangguan, J F, Song, Y X, Sosio, S, Su, Y J, Sun, Y J, Teng, J X, Uman, I, Wang, C W, Wang, D Y, Wang, K, Wang, Y Q, Wang, Yi, Wang, Ziyi, Wei, D H, Weidner, F, Wiedner, U, Wilkinson, G, Wolke, M, Wu, L J, Wu, Y, Xian, X M, Xiao, G Y, Xie, X H, Xu, C J, Xu, G F, Xu, Z P, Yan, F, Yan, W B, Ye, M H, You, Z Y, Yu, G, Yuan, S C, Yuan, Y, Yuan, Z Y, Zeng, F R, Zhan, Y H, Zhang, B X, Zhang, J W, Zhang, J Y, Zhang, Jiawei, Zhang, Lei, Zhang, P, Zhang, Q Y, Zhang, Shulei, Zhang, Y H, Zhang, Z L, Zhu, K, Zhu, S H, Zhu, Y C
• Format: Article
• Language: English
• ISSN: 0031-9007; 1079-7114; 1079-7114
• DOI: 10.1103/PhysRevLett.131.151901

A narrow structure in the pΛ[over ¯] system near the mass threshold, named as X(2085), is observed in the process e^{+}e^{-}→pK^{-}Λ[over ¯] with a statistical significance greater than 20σ. Its spin and parity are determined for the first time to be J^{P}=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 M_{pole}=(2084_{-2}^{+4}±9)  MeV and Γ_{pole}=(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^{-}Λ[over ¯] and uses the data samples collected with the BESIII detector at the center-of-mass energies sqrt[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}.