Measurement of the Branching Fraction of and Search for a CP-Violating Asymmetry in $η' \to π^+ π^- e^+ e^-$ at BESIII
Creators: name: BESIII Collaboration
name: Ablikim, M.
name: Achasov, M. N.
name: Adlarson, P.
name: Ahmed, S.
name: Albrecht, M.
name: Amoroso, A.
name: An, Q.
name: Bai, X. H.
name: Bai, Y.
name: Bakina, O.
name: Ferroli, R. Baldini
name: Balossino, I.
name: Ban, Y.
name: Begzsuren, K.
name: Bennett, J. V.
name: Berger, N.
name: Bertani, M.
name: Bettoni, D.
name: Bianchi, F.
name: Biernat, J
name: Bloms, J.
name: Bortone, A.
name: Boyko, I.
name: Briere, R. A.
name: Cai, H.
name: Cai, X.
name: Calcaterra, A.
name: Cao, G. F.
name: Cao, N.
name: Cetin, S. A.
name: Chang, J. F.
name: Chang, W. L.
name: Chelkov, G.
name: Chen, D. Y.
name: Chen, G.
name: Chen, H. S.
name: Chen, M. L.
name: Chen, S. J.
name: Chen, X. R.
name: Chen, Y. B.
name: Chen, Z. J
name: Cheng, W. S.
name: Cibinetto, G.
name: Cossio, F.
name: Cui, X. F.
name: Dai, H. L.
name: Dai, J. P.
name: Dai, X. C.
name: Dbeyssi, A.
name: de Boer, R. E.
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: Dong, J.
name: Dong, L. Y.
name: Dong, M. Y.
name: Du, S. X.
name: Fang, J.
name: Fang, S. S.
name: Fang, Y.
name: Farinelli, R.
name: Fava, L.
name: Feldbauer, F.
name: Felici, G.
name: Feng, C. Q.
name: Fritsch, M.
name: Fu, C. D.
name: Fu, Y.
name: Gao, X. L.
name: Gao, Y.
name: Gao, Y.
name: Gao, Y.
name: Gao, Y. G.
name: Garzia, I.
name: Gersabeck, E. M.
name: Gilman, A.
name: Goetzen, K.
name: Gong, L.
name: Gong, W. X.
name: Gradl, W.
name: Greco, M.
name: Gu, L. M.
name: Gu, M. H.
name: Gu, S.
name: Gu, Y. T.
name: Guan, C. Y
name: Guo, A. Q.
name: Guo, L. B.
name: Guo, R. P.
name: Guo, Y. P.
name: Guskov, A.
name: Han, S.
name: Han, T. T.
name: Han, T. Z.
name: Hao, X. Q.
name: Harris, F. A.
name: Hüsken, N.
name: He, K. L.
name: Heinsius, F. H.
name: Held, T.
name: Heng, Y. K.
name: Himmelreich, M.
name: Holtmann, T.
name: Hou, Y. R.
name: Hou, Z. L.
name: Hu, H. M.
name: Hu, J. F.
name: Hu, T.
name: Hu, Y.
name: Huang, G. S.
name: Huang, L. Q.
name: Huang, X. T.
name: Huang, Y. P.
name: Huang, Z.
name: Hussain, T.
name: Andersson, W. Ikegami
name: Imoehl, W.
name: Irshad, M.
name: Jaeger, S.
name: Janchiv, S.
name: Ji, Q.
name: Ji, Q. P.
name: Ji, X. B.
name: Ji, X. L.
name: Jiang, H. B.
name: Jiang, X. S.
name: Jiao, J. B.
name: Jiao, Z.
name: Jin, S.
name: Jin, Y.
name: Johansson, T.
name: Kalantar-Nayestanaki, N.
name: Kang, X. S.
name: Kappert, R.
name: Kavatsyuk, M.
name: Ke, B. C.
name: Keshk, I. K.
name: Khoukaz, A.
name: Kiese, P.
name: Kiuchi, R.
name: Kliemt, R.
name: Koch, L.
name: Kolcu, O. B.
name: Kopf, B.
name: Kuemmel, M.
name: Kuessner, M.
name: Kupsc, A.
name: Kurth, M. G.
name: Kühn, W.
name: Lane, J. J.
name: Lange, J. S.
name: Larin, P.
name: Lavania, A.
name: Lavezzi, L.
name: Leithoff, H.
name: Lellmann, M.
name: Lenz, T.
name: Li, C.
name: Li, C. H.
name: Li, Cheng
name: Li, D. M.
name: Li, F.
name: Li, G.
name: Li, H.
name: Li, H. B.
name: Li, H. J.
name: Li, J. L.
name: Li, J. Q.
name: Li, Ke
name: Li, L. K.
name: Li, Lei
name: Li, P. L.
name: Li, P. R.
name: Li, S. Y.
name: Li, W. D.
name: Li, W. G.
name: Li, X. H.
name: Li, X. L.
name: Li, Z. Y.
name: Liang, H.
name: Liang, H.
name: Liang, Y. F.
name: Liang, Y. T.
name: Liao, L. Z.
name: Libby, J.
name: Lin, C. X.
name: Liu, B.
name: Liu, B. J.
name: Liu, C. X.
name: Liu, D.
name: Liu, D. Y.
name: Liu, F. H.
name: Liu, Fang
name: Liu, Feng
name: Liu, H. B.
name: Liu, H. M.
name: Liu, Huanhuan
name: Liu, Huihui
name: Liu, J. B.
name: Liu, J. Y.
name: Liu, K.
name: Liu, K. Y.
name: Liu, Ke
name: Liu, L.
name: Liu, Q.
name: Liu, S. B.
name: Liu, Shuai
name: Liu, T.
name: Liu, W. M.
name: Liu, X.
name: Liu, Y. B.
name: Liu, Z. A.
name: Liu, Z. Q.
name: Long, Y. F.
name: Lou, X. C.
name: Lu, F. X.
name: Lu, H. J.
name: Lu, J. D.
name: Lu, J. G.
name: Lu, X. L.
name: Lu, Y.
name: Lu, Y. P.
name: Luo, C. L.
name: Luo, M. X.
name: Luo, P. W.
name: Luo, T.
name: Luo, X. L.
name: Lusso, S.
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, R. Q.
name: Ma, R. T.
name: Ma, X. N.
name: Ma, X. X.
name: Ma, X. Y.
name: Ma, Y. M.
name: Maas, F. E.
name: Maggiora, M.
name: Maldaner, S.
name: Malde, S.
name: Malik, Q. A.
name: Mangoni, 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, T. J.
name: Mitchell, R. E.
name: Mo, X. H.
name: Mo, Y. J.
name: Muchnoi, N. Yu.
name: Muramatsu, H.
name: Nakhoul, S.
name: Nefedov, Y.
name: Nerling, F.
name: Nikolaev, I. B.
name: Ning, Z.
name: Nisar, S.
name: Olsen, S. L.
name: Ouyang, Q.
name: Pacetti, S.
name: Pan, X.
name: Pan, Y.
name: Pathak, A.
name: Patteri, P.
name: Pelizaeus, M.
name: Peng, H. P.
name: Peters, K.
name: Pettersson, J.
name: Ping, J. L.
name: Ping, R. G.
name: Pitka, A.
name: Poling, R.
name: Prasad, V.
name: Qi, H.
name: Qi, H. R.
name: Qi, M.
name: Qi, T. Y.
name: Qi, T. Y.
name: Qian, S.
name: Qian, W. B.
name: Qian, Z.
name: Qiao, C. F.
name: Qin, L. Q.
name: Qin, X. S.
name: Qin, Z. H.
name: Qiu, J. F.
name: Qu, S. Q.
name: Rashid, K. H.
name: Ravindran, K.
name: Redmer, C. F.
name: Rivetti, A.
name: Rodin, V.
name: Rolo, M.
name: Rong, G.
name: Rosner, Ch.
name: Rump, M.
name: Sarantsev, A.
name: Schelhaas, Y.
name: Schnier, C.
name: Schoenning, K.
name: Shan, D. C.
name: Shan, W.
name: Shan, X. Y.
name: Shao, M.
name: Shen, C. P.
name: Shen, P. X.
name: Shen, X. Y.
name: Shi, H. C.
name: Shi, R. S.
name: Shi, X.
name: Shi, X. D
name: Song, J. J.
name: Song, Q. Q.
name: Song, W. M.
name: Song, Y. X.
name: Sosio, S.
name: Spataro, S.
name: Sui, F. F.
name: Sun, G. X.
name: Sun, J. F.
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name: Sun, S. S.
name: Sun, T.
name: Sun, W. Y.
name: Sun, X
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name: Sun, Z. T.
name: Tan, Y. H.
name: Tan, Y. X.
name: Tang, C. J.
name: Tang, G. Y.
name: Tang, J.
name: Teng, J. X.
name: Thoren, V.
name: Uman, I.
name: Wang, B.
name: Wang, B. L.
name: Wang, C. W.
name: Wang, D. Y.
name: Wang, H. P.
name: Wang, K.
name: Wang, L. L.
name: Wang, M.
name: Wang, M. Z.
name: Wang, Meng
name: Wang, W. H.
name: Wang, W. P.
name: Wang, X.
name: Wang, X. F.
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name: Wang, Y.
name: Wang, Y. D.
name: Wang, Y. F.
name: Wang, Y. Q.
name: Wang, Z.
name: Wang, Z. Y.
name: Wang, Ziyi
name: Wang, Zongyuan
name: Wei, D. H.
name: Weidenkaff, P.
name: Weidner, F.
name: Wen, S. P.
name: White, D. J.
name: Wiedner, U.
name: Wilkinson, G.
name: Wolke, M.
name: Wollenberg, L.
name: Wu, J. F.
name: Wu, L. H.
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name: Wu, X.
name: Wu, Z.
name: Xia, L.
name: Xiao, H.
name: Xiao, S. Y.
name: Xiao, Y. J.
name: Xiao, Z. J.
name: Xie, X. H.
name: Xie, Y. G.
name: Xie, Y. H.
name: Xing, T. Y.
name: Xiong, X. A.
name: Xu, G. F.
name: Xu, J. J.
name: Xu, Q. J.
name: Xu, W.
name: Xu, X. P.
name: Xu, Y. C.
name: Yan, F.
name: Yan, L.
name: Yan, L.
name: Yan, W. B.
name: Yan, W. C.
name: Yan, Xu
name: Yang, H. J.
name: Yang, H. X.
name: Yang, L.
name: Yang, R. X.
name: Yang, S. L.
name: Yang, Y. H.
name: Yang, Y. X.
name: Yang, Yifan
name: Yang, Zhi
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, G.
name: Yu, J. S.
name: Yu, T.
name: Yuan, C. Z.
name: Yuan, W.
name: Yuan, X. Q.
name: Yuan, Y.
name: Yuan, Z. Y.
name: Yue, C. X.
name: Yuncu, A.
name: Zafar, A. A.
name: Zeng, Y.
name: Zhang, B. X.
name: Zhang, Guangyi
name: Zhang, H.
name: Zhang, H. H.
name: Zhang, H. Y.
name: Zhang, J. L.
name: Zhang, J. Q.
name: Zhang, J. Q.
name: Zhang, J. W.
name: Zhang, J. Y.
name: Zhang, J. Z.
name: Zhang, Jianyu
name: Zhang, Jiawei
name: Zhang, Lei
name: Zhang, S.
name: Zhang, S. F.
name: Zhang, T. J.
name: Zhang, X. Y.
name: Zhang, Y.
name: Zhang, Y. H.
name: Zhang, Y. T.
name: Zhang, Yan
name: Zhang, Yao
name: Zhang, Yi
name: Zhang, Z. H.
name: Zhang, Z. Y.
name: Zhao, G.
name: Zhao, J.
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name: Zhao, J. Z.
name: Zhao, Lei
name: Zhao, Ling
name: Zhao, M. G.
name: Zhao, Q.
name: Zhao, S. J.
name: Zhao, Y. B.
name: Zhao, Y. X.
name: Zhao, Z. G.
name: Zhemchugov, A.
name: Zheng, B.
name: Zheng, J. P.
name: Zheng, Y.
name: Zheng, Y. H.
name: Zhong, B.
name: Zhong, C.
name: Zhou, L. P.
name: Zhou, Q.
name: Zhou, X.
name: Zhou, X. K.
name: Zhou, X. R.
name: Zhu, A. N.
name: Zhu, J.
name: Zhu, K.
name: Zhu, K. J.
name: Zhu, S. H.
name: Zhu, W. J.
name: Zhu, Y. C.
name: Zhu, Z. A.
name: Zou, B. S.
name: Zou, J. H.
Publisher: name: arXiv
Year: 2020
Subjects: subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: The rare decay $η' \to π^+ π^- e^+ e^-$ is studied using a sample of $1.3 \times 10^9$ $J/ψ$ events collected with the BESIII detector at BEPCII in 2009 and 2012. The branching fraction is measured with improved precision to be $\left( 2.42\pm0.05_{stat.}\pm0.08_{syst.} \right) \times 10^{-3}$. Due to the inclusion of new data, this result supersedes the last BESIII result on this branching fraction. In addition, the CP-violating asymmetry in the angle between the decay planes of the $π^+π^-$-pair and the $e^+e^-$-pair is investigated. A measurable value would indicate physics beyond the standard model; the result is $\mathcal{A}_{CP} = \left(2.9\pm3.7_{stat.}\pm1.1_{syst.} \right)\%$, which is consistent with the standard model expectation of no CP-violation. The precision is comparable to the asymmetry measurement in the $K^0_L\toπ^+π^-e^+e^-$ decay where the observed $(14\pm2)\%$ effect is driven by a standard model mechanism.
description: 10 pages, 8 figures, 3 tables