First observation of the M1 transition ψ(3686)→γη(c)(2S).

Journal: Physical Review Letters
Published:
Abstract

Using a sample of 106×10(6) ψ(3686) events collected with the BESIII detector at the BEPCII storage ring, we have made the first measurement of the M1 transition between the radially excited charmonium S-wave spin-triplet and the radially excited S-wave spin-singlet states: ψ(3686)→γη(c)(2S). Analyses of the processes ψ(3686)→γη(c)(2S) with η(c)(2S)→K(S)(0)K(±)π(∓) and K(+)K(-)π(0) give an η(c)(2S) signal with a statistical significance of greater than 10 standard deviations under a wide range of assumptions about the signal and background properties. The data are used to obtain measurements of the η(c)(2S) mass (M(η(c)(2S))=3637.6±2.9(stat)±1.6(syst) MeV/c(2)), width (Γ(η(c)(2S))=16.9±6.4(stat)±4.8(syst) MeV), and the product branching-fraction (B(ψ(3686)→γη(c)(2S))×B(η(c)(2S)→KKπ)=(1.30±0.20(stat)±0.30(syst))×10(-5)). Combining our result with a BABAR measurement of B(η(c)(2S)→KKπ), we find the branching fraction of the M1 transition to be B(ψ(3686)→γη(c)(2S))=(6.8±1.1(stat)±4.5(syst))×10(-4).

Authors
M Ablikim, M Achasov, D Ambrose, F An, Q An, Z An, J Bai, Y Ban, J Becker, N Berger, M Bertani, J Bian, E Boger, O Bondarenko, I Boyko, R Briere, V Bytev, X Cai, A Calcaterra, G Cao, J Chang, G Chelkov, G Chen, H Chen, J Chen, M Chen, S Chen, Y Chen, Y Chen, H Cheng, Y Chu, D Cronin Hennessy, H Dai, J Dai, D Dedovich, Z Deng, A Denig, I Denysenko, M Destefanis, W Ding, Y Ding, L Dong, M Dong, S Du, J Fang, S Fang, L Fava, F Feldbauer, C Feng, R Ferroli, C Fu, J Fu, Y Gao, C Geng, K Goetzen, W Gong, W Gradl, M Greco, M Gu, Y Gu, Y Guan, A Guo, L Guo, Y Guo, Y Han, X Hao, F Harris, K He, M He, Z He, T Held, Y Heng, Z Hou, H Hu, J Hu, T Hu, B Huang, G Huang, J Huang, X Huang, Y Huang, T Hussain, C Ji, Q Ji, X Ji, X Ji, L Jia, L Jiang, X Jiang, J Jiao, Z Jiao, D Jin, S Jin, F Jing, N Kalantar Nayestanaki, M Kavatsyuk, W Kuehn, W Lai, J Lange, J K Leung, C Li, Cheng Li, Cui Li, D Li, F Li, G Li, H Li, J Li, K Li, Lei Li, N Li, Q Li, S Li, W Li, W Li, X Li, X Li, X Li, X Li, Z Li, H Liang, Y Liang, Y Liang, G Liao, X Liao, B Liu, C Liu, C Liu, C Liu, F Liu, Fang Liu, Feng Liu, H Liu, H Liu, H Liu, J Liu, K Liu, Kai Liu, Kun Liu, P Liu, S Liu, X Liu, X Liu, Y Liu, Y Liu, Z Liu, Zhiqiang Liu, Zhiqing Liu, H Loehner, G Lu, H Lu, J Lu, Q Lu, X Lu, Y Lu, C Luo, M Luo, T Luo, X Luo, M Lv, C Ma, F Ma, H Ma, Q Ma, S Ma, T Ma, X Ma, Y Ma, F Maas, M Maggiora, Q Malik, H Mao, Y Mao, Z Mao, J Messchendorp, J Min, T Min, R Mitchell, X Mo, C Morales, C Motzko, N Muchnoi, Y Nefedov, C Nicholson, I Nikolaev, Z Ning, S Olsen, Q Ouyang, S Pacetti, J Park, M Pelizaeus, H Peng, K Peters, J Ping, R Ping, R Poling, E Prencipe, C S Pun, M Qi, S Qian, C Qiao, X Qin, Y Qin, Z Qin, J Qiu, K Rashid, G Rong, X Ruan, A Sarantsev, B Schaefer, J Schulze, M Shao, C Shen, X Shen, H Sheng, M Shepherd, X Song, S Spataro, B Spruck, D Sun, G Sun, J Sun, S Sun, X Sun, Y Sun, Y Sun, Z Sun, Z Sun, C Tang, X Tang, E Thorndike, H Tian, D Toth, M Ullrich, G Varner, B Wang, B Wang, K Wang, L Wang, L Wang, M Wang, P Wang, P Wang, Q Wang, Q Wang, S Wang, X Wang, X Wang, Y Wang, Y Wang, Y Wang, Z Wang, Z Wang, Z Wang, D Wei, P Weidenkaff, Q Wen, S Wen, M Werner, U Wiedner, L Wu, N Wu, S Wu, W Wu, Z Wu, L Xia, Z Xiao, Y Xie, Q Xiu, G Xu, G Xu, H Xu, Q Xu, X Xu, Y Xu, Z Xu, F Xue, Z Xue, L Yan, W Yan, Y Yan, H Yang, T Yang, Y Yang, Y Yang, H Ye, M Ye, M Ye, B Yu, C Yu, J Yu, L Yu, S Yu, C Yuan, W Yuan, Y Yuan, A Zafar, A Zallo, Y Zeng, B Zhang, B Zhang, C Zhang, D Zhang, H Zhang, H Zhang, J Zhang, J Zhang, J Zhang, J Zhang, J Zhang, L Zhang, S Zhang, T Zhang, X Zhang, X Zhang, Y Zhang, Y Zhang, Y Zhang, Z Zhang, Z Zhang, G Zhao, H Zhao, J Zhao, K Zhao, Lei Zhao, Ling Zhao, M Zhao, Q Zhao, S Zhao, T Zhao, X Zhao, Y Zhao, Z Zhao, A Zhemchugov, B Zheng, J Zheng, Y Zheng, Z Zheng, B Zhong, J Zhong, L Zhou, X Zhou, X Zhou, C Zhu, K Zhu, K Zhu, S Zhu, X Zhu, X Zhu, Y Zhu, Y Zhu, Z Zhu, J Zhuang, B Zou, J Zou, J Zuo