Improved measurements of two-photon widths of the $χ_{cJ}$ states and helicity analysis for $χ_{c2}\toγγ$
Creators: name: BESIII Collaboration
name: Ablikim, M.
name: Achasov, M. N.
name: Ahmed, S.
name: Albrecht, M.
name: Amoroso, A.
name: An, F. F.
name: An, Q.
name: Bai, J. Z.
name: Bai, Y.
name: Bakina, O.
name: Ferroli, R. Baldini
name: Ban, Y.
name: Bennett, D. W.
name: Bennett, J. V.
name: Berger, N.
name: Bertani, M.
name: Betton, D.
name: Bian, J. M.
name: Bianchi, F.
name: Boger, E.
name: Boyko, I.
name: Briere, R. A.
name: Cai, H.
name: Cai, X.
name: Cakir, O.
name: Calcaterra, A.
name: Cao, G. F.
name: Cetin, S. A.
name: Chai, J.
name: Chang, J. F.
name: Chelkov, G.
name: Chen, G.
name: Chen, H. S.
name: Chen, J. C.
name: Chen, M. L.
name: Chen, S. J.
name: Chen, X. R.
name: Chen, Y. B.
name: Chu, X. K.
name: Cibinetto, G.
name: Dai, H. L.
name: Dai, J. P.
name: Dbeyssi, A.
name: Dedovich, D.
name: Deng, Z. Y.
name: Denig, A.
name: Denysenko, I.
name: Destefanis, M.
name: De Mori, F.
name: Ding, Y.
name: Dong, C.
name: ng, J. Do
name: Dong, L. Y.
name: Dong, M. Y.
name: Dorjkhaidav, O.
name: Dou, Z. L.
name: Du, S. X.
name: Duan, P. F.
name: Fang, J.
name: Fang, S. S.
name: Fang, X.
name: Fang, Y.
name: Farinelli, R.
name: Fava, L.
name: Fegan, S.
name: Feldbauer, F.
name: Felici, G.
name: Feng, C. Q.
name: Fioravanti, E.
name: Fritsch, M.
name: Fu, C. D.
name: Gao, Q.
name: Gao, X. L.
name: Gao, Y.
name: Gao, Y. G.
name: Gao, Z.
name: Garzia, I.
name: Goetzen, K.
name: Gong, L.
name: Gong, W. X.
name: Gradl, W.
name: Greco, M.
name: Gu, M. H.
name: Gu, S.
name: Gu, Y. T.
name: Guo, A. Q.
name: Guo, L. B.
name: Guo, R. P.
name: Guo, Y. P.
name: Haddadi, Z.
name: Han, S.
name: Hao, X. Q.
name: Harris, F. A.
name: He, K. L.
name: He, X. Q.
name: Heinsius, F. H.
name: Held, T.
name: Heng, Y. K.
name: Holtmann, T.
name: Hou, Z. L.
name: Hu, C.
name: Hu, H. M.
name: Hu, T.
name: Hu, Y.
name: Huang, G. S.
name: Huang, J. S.
name: Huang, X. T.
name: Huang, X. Z.
name: Huang, Z. L.
name: Hussain, T.
name: Andersson, W. Ikegami
name: Ji, Q.
name: Ji, Q. P.
name: Ji, X. B.
name: Ji, X. L.
name: Jiang, X. S.
name: Jiang, X. Y.
name: Jiao, J. B.
name: Jiao, Z.
name: Jin, D. P.
name: Jin, S.
name: Jin, Y.
name: Johansson, T.
name: Julin, A.
name: alantar-Nayestanaki, N. K
name: Kang, X. L.
name: Kang, X. S.
name: Kavatsyuk, M.
name: Ke, B. C.
name: Khan, T.
name: Khoukaz, A.
name: Kiese, P.
name: Kliemt, R.
name: Koch, L.
name: Kolcu, O. B.
name: Kopf, B.
name: Kornicer, M.
name: Kuemmel, M.
name: Kuhlmann, M.
name: Kupsc, A.
name: Kühn, W.
name: Lange, J. S.
name: Lara, M.
name: Larin, P.
name: Lavezzi, L.
name: Leithoff, H.
name: Leng, C.
name: Li, C.
name: Li, Cheng
name: Li, D. M.
name: Li, F.
name: Li, F. Y.
name: Li, G.
name: Li, H. B.
name: Li, H. J.
name: Li, J. C.
name: Li, Jin
name: Li, K.
name: Li, K.
name: Li, K. J.
name: Li, Lei
name: Li, P. L.
name: Li, P. R.
name: Li, Q. Y.
name: Li, T.
name: Li, W. D.
name: Li, W. G.
name: Li, X. L.
name: Li, X. N.
name: Li, X. Q.
name: Li, Z. B.
name: Liang, H.
name: Liang, Y. F.
name: Liang, Y. T.
name: Liao, G. R.
name: Lin, D. X.
name: Liu, B.
name: Liu, B. J.
name: Liu, C. X.
name: Liu, D.
name: Liu, F. H.
name: Liu, Fang
name: Liu, Feng
name: Liu, H. B.
name: Liu, H. H.
name: Liu, H. H.
name: Liu, H. M.
name: Liu, J. B.
name: Liu, J. P.
name: Liu, J. Y.
name: Liu, K.
name: Liu, K. Y.
name: Liu, Ke
name: Liu, L. D.
name: Liu, P. L.
name: Liu, Q.
name: Liu, S. B.
name: Liu, X.
name: Liu, Y. B.
name: Liu, Y. Y.
name: Liu, Z. A.
name: Liu, Zhiqing
name: Long, Y. F.
name: Lou, X. C.
name: Lu, H. J.
name: Lu, J. G.
name: Lu, Y.
name: Lu, Y. P.
name: Luo, C. L.
name: Luo, M. X.
name: Luo, X. L.
name: Lyu, X. R.
name: Ma, F. C.
name: Ma, H. L.
name: Ma, L. L.
name: Ma, M. M.
name: Ma, Q. M.
name: Ma, T.
name: Ma, X. N.
name: Ma, X. Y.
name: Ma, Y. M.
name: Maas, F. E.
name: Maggiora, M.
name: Malik, Q. A.
name: Mao, Y. J.
name: Mao, Z. P.
name: Marcello, S.
name: Meng, Z. X.
name: Messchendorp, J. G.
name: Mezzadri, G.
name: Min, J.
name: Min, T. J.
name: Mitchell, R. E.
name: Mo, X. H.
name: Mo, Y. J.
name: Morales, C. Morales
name: Morello, G.
name: Muchnoi, N. Yu.
name: Muramatsu, H.
name: Musiol, P.
name: Mustafa, A.
name: Nefedov, Y.
name: Nerling, F.
name: Nikolaev, I. B.
name: Ning, Z.
name: Nisar, S.
name: Niu, S. L.
name: Niu, X. Y.
name: Olsen, S. L.
name: Ouyang, Q.
name: Pacetti, S.
name: Pan, Y.
name: Patter, P.
name: Pelizaeus, M.
name: Pellegrino, J.
name: Peng, H. P.
name: Peters, K.
name: Pettersson, J.
name: Ping, J. L.
name: Ping, R. G.
name: Poling, R.
name: Prasad, V.
name: Qi, H. R.
name: Qi, M.
name: Qian, S.
name: Qiao, C. F.
name: Qin, J. J.
name: Qin, N.
name: Qin, X. S.
name: Qin, Z. H.
name: Qiu, J. F.
name: Rashid, K. H.
name: Redmer, C. F.
name: Richter, M.
name: Ripka, M.
name: Rolo, M.
name: Rong, G.
name: Rosner, Ch.
name: Ruan, X. D.
name: Sarantsev, A.
name: Savrié, M.
name: Schnier, C.
name: Schoenning, K.
name: Shan, W.
name: Shao, M.
name: Shen, C. P.
name: Shen, P. X.
name: Shen, X. Y.
name: Sheng, H. Y.
name: Song, J. J.
name: Song, X. Y.
name: Sosio, S.
name: Sowa, C.
name: Spataro, S.
name: Sun, G. X.
name: Sun, J. F.
name: Sun, L.
name: Sun, S. S.
name: Sun, X. H.
name: Sun, Y. J.
name: Sun, Y. K
name: Sun, Y. Z.
name: Sun, Z. J.
name: Sun, Z. T.
name: Tang, C. J.
name: ng, G. Y. Ta
name: Tang, X.
name: Tapan, I.
name: Tiemens, M.
name: Tsednee, B. T.
name: Uman, I.
name: Varner, G. S.
name: Wang, B.
name: Wang, B. L.
name: Wang, D.
name: Wang, D. Y.
name: Wang, Dan
name: Wang, K.
name: Wang, L. L.
name: Wang, L. S.
name: Wang, M.
name: Wang, P.
name: Wang, P. L.
name: Wang, W. P.
name: Wang, X. F.
name: Wang, Y. D.
name: Wang, Y. F.
name: Wang, Y. Q.
name: Wang, Z.
name: Wang, Z. G.
name: Wang, Z. H.
name: Wang, Z. Y.
name: Wang, Z. Y.
name: Weber, T.
name: Wei, D. H.
name: Weidenkaff, P.
name: Wen, S. P.
name: Wiedner, U.
name: Wolke, M.
name: Wu, L. H.
name: Wu, L. J.
name: Wu, Z.
name: Xia, L.
name: Xia, Y.
name: Xiao, D.
name: Xiao, H.
name: Xiao, Y. J.
name: Xiao, Z. J.
name: Xie, Y. G.
name: Xie, Y. H.
name: Xiong, X. A.
name: Xiu, Q. L.
name: Xu, G. F.
name: Xu, J. J.
name: Xu, L.
name: Xu, Q. J.
name: Xu, Q. N.
name: Xu, X. P.
name: Yan, L.
name: Yan, W. B.
name: Yan, W. C.
name: an, Y. H. Y
name: Yang, H. J.
name: Yang, H. X.
name: Yang, L.
name: Yang, Y. H.
name: Yang, Y. X.
name: Ye, M.
name: Ye, M. H.
name: Yin, J. H.
name: You, Z. Y.
name: Yu, B. X.
name: Yu, C. X.
name: Yu, J. S.
name: Yuan, C. Z.
name: Yuan, Y.
name: Yuncu, A.
name: Zafar, A. A.
name: Zeng, Y.
name: Zeng, Z.
name: ang, B. X. Zh
name: Zhang, B. Y.
name: Zhang, C. C.
name: Zhang, D. H.
name: Zhang, H. H.
name: Zhang, H. Y.
name: Zhang, J.
name: Zhang, J. L.
name: Zhang, J. Q.
name: Zhang, J. W.
name: Zhang, J. Y.
name: Zhang, J. Z.
name: Zhang, K.
name: Zhang, L.
name: Zhang, S. Q.
name: Zhang, X. Y.
name: Zhang, Y.
name: Zhang, Y.
name: Zhang, Y. H.
name: Zhang, Y. T.
name: Zhang, Yu
name: Zhang, Z. H.
name: Zhang, Z. P.
name: Zhang, Z. Y.
name: Zhao, G.
name: Zhao, J. W.
name: Zhao, J. Y.
name: Zhao, J. Z.
name: Zhao, Lei
name: Zhao, Ling
name: Zhao, M. G.
name: Zhao, Q.
name: Zhao, S. J.
name: Zhao, T. C.
name: Zhao, Y. B.
name: Zhao, Z. G.
name: Zhemchugov, A.
name: Zheng, B.
name: Zheng, J. P.
name: Zheng, W. J.
name: Zheng, Y. H.
name: Zhong, B.
name: Zhou, L.
name: Zhou, X.
name: Zhou, X. K.
name: Zhou, X. R.
name: Zhou, X. Y.
name: Zhou, Y. X.
name: Zhu, J.
name: Zhu, K.
name: Zhu, K. J.
name: Zhu, S.
name: Zhu, S. H.
name: Zhu, X. L.
name: Zhu, Y. C.
name: Zhu, Y. S.
name: Zhu, Z. A.
name: Zhuang, J.
name: Zotti, L.
name: Zou, B. S.
name: Zou, J. H.
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: Based on $448.1 \times 10^6$ $ψ(3686)$ events collected with the BESIII detector, the decays $ψ(3686)\toγχ_{cJ}, χ_{cJ} \to γγ~(J=0, 1, 2)$ are studied. The decay branching fractions of $χ_{c0,c2} \to γγ$ are measured to be $\mathcal{B}(χ_{c0}\toγγ) = (1.93 \pm 0.08 \pm 0.05 \pm 0.05)\times 10^{-4}$ and $\mathcal{B}(χ_{c2}\toγγ) = (3.10 \pm 0.09 \pm 0.07 \pm 0.11)\times 10^{-4} $, which correspond to two-photon decay widths of $Γ_{γγ}(χ_{c0}) = 2.03 \pm 0.08 \pm 0.06 \pm 0.13 ~\rm{keV}$ and $Γ_{γγ}(χ_{c2}) = 0.60 \pm 0.02 \pm 0.01 \pm 0.04 ~\rm{keV}$ with a ratio of $\mathcal{R}=Γ_{γγ}(χ_{c2})/Γ_{γγ}(χ_{c0})= 0.295 \pm 0.014 \pm 0.007 \pm 0.027$, where the uncertainties are statistical, systematic and associated with the uncertainties of $\mathcal{B}(ψ(3686)\toγχ_{c0,c2})$ and the total widths $Γ(χ_{c0,c2})$, respectively. For the forbidden decay of $χ_{c1}\toγγ$, no signal is observed, and an upper limit on the two-photon width is obtained to be $Γ_{γγ}(χ_{c1})&lt;5.3 ~\rm{eV}$ at the 90\% confidence level. The ratio of the two-photon widths between helicity-zero and helicity-two components in the decay $χ_{c2}\toγγ$ is also measured to be $f_{0/2} = Γ^{λ=0}_{γγ}(χ_{c2})/Γ^{λ=2}_{γγ}(χ_{c2}) = (0.0 \pm 0.6 \pm 1.2)\times 10^{-2}$, where the uncertainties are statistical and systematic, respectively.
description: 11 pages, 4 figures, 4 tables