Open Access

Medina Ablikim, Mikhail N. Achasov, Patrik Adlarson, Samer Ahmed, Malte Albrecht, Antonio Amoroso, Qi An, Anita, Y. Bai, Olga Bakina, Rinaldo Baldini Ferroli, Ilaria Balossino, Yong Ban, Khurelbaatar Begzsuren, Jake V. Bennett, Niklaus Berger, Monica Bertani, Diego Bettoni, Fabrizio Bianchi, Jacek Biernat, Johannes Bloms, Alberto Bortone, Igor R. Boyko, Roy A. Briere, H. Cai, Xiao Cai, Alessandro Calcaterra, G. F. Cao, Ning Cao, Serkant Ali Çetin, Jinfan Chang, W. L. Chang, Gueorgui A. Chelkov, D. Y. Chen, G. Chen, Hesheng Chen, M. L. Chen, S. J. Chen, X. R. Chen, Yuanbo Chen, W. Cheng, Gianluigi Cibinetto, Fabio Cossio, X. F. Cui, Hongliang Dai, J. P. Dai, Xinchen Dai, Alaa Dbeyssi, Remco E. de Boer, Dmitri V. Dedovich, Ziyan Deng, Achim Denig, Igor Denysenko, Marco Giovanni Maria Destefanis, Francesca De Mori, Y. Ding, C. Dong, J. Dong, Liaoyuan Dong, Mingyi Dong, Shuxian Du, J. Fang, Shuangshi Fang, Y. Fang, Riccardo Farinelli, Luciano Fava, Florian Feldbauer, Giulietto Felici, C. Q. Feng, Miriam Fritsch, Chengdong Fu, Ying Fu, X. L. Gao, Y. Gao, Y. Gao, Y. G. Gao, I. Garzia, Evelina Gersabeck, Alexander Gilman, Klaus Goetzen, L. Gong, Wenxuan Gong, Wolfgang Gradl, M. Greco, L. M. Gu, Minhao Gu, S. Gu, Y. T. Gu, C. Y. Guan, Aiqiang Guo, L. B. Guo, R. P. Guo, Yuping Guo, Yuping Guo, Alexey Guskov, S. Han, T. T. Han, T. Z. Han, Xiqing Hao, F. A. Harris, K. L. He, Fritz-Herbert Heinsius, T. Held, Yuekun Heng, Mathilde Himmelreich, Tobias Holtmann, Y. R. Hou, Zhilong Hou, Haiming Hu, J. F. Hu, T. Hu, Y. Hu, G. S. Huang, L. Q. Huang, X. T. Huang, Z. Huang, Nils Huesken, Tahir Hussain, Walter Ikegami Andersson, William Imoehl, Muzaffar Irshad, S. Jaeger, S. Janchiv, Quan Ji, Qingping Ji, X. B. Ji, X. L. Ji, H. B. Jiang, Xiaoshan Jiang, X. Y. Jiang, J. B. Jiao, Z. Jiao, Shan Jin, Y. Jin, Tord Johansson, Nasser Kalantar-Nayestanaki, Xiaolin Kang, Rosa Kappert, Myroslav O. Kavatsyuk, Bai-Cian Ke, Iman Keshk, Alfons Khoukaz, P. Kiese, Ryuta Kiuchi, Ralf Kliemt, Leonard Koch, Onur Bugra Kolcu, Bertram Kopf, Miriam Kümmel, Meike Küßner, Andrzej Kupsc, M. G. Kurth, Wolfgang Kühn, John Jake Lane, Jens Sören Lange, Paul Larin, Lia Lavezzi, Hans Heinrich Leithoff, Max Lellmann, Thomas Lenz, C. Li, Chunhua Li, Cheng Li, D. M. Li, F. Li, G. Li, Haibo Li, Huijing Li, J. L. Li, J. Q. Li, Ke Li, L. K. Li, Lei Li, P. L. Li, Peirong Li, Shuaiying Li, Weidong Li, Weiguo Li, X. H. Li, X. L. Li, Z. B. Li, Z. Y. Li, H. Liang, H. Liang, Y. F. Liang, Y. T. Liang, L. Z. Liao, J. Libby, C. X. Lin, B. Liu, B. J. Liu, C. X. Liu, D. Liu, D. Y. Liu, Fu-Hu Liu, Fang Liu, Feng Liu, H. B. Liu, H. M. Liu, Huanhuan Liu, Huihui Liu, J. B. Liu, J. Y. Liu, K. Liu, K. Y. Liu, Ke Liu, L. Liu, Q. Liu, S. B. Liu, Shuai Liu, Tong Liu, X. Liu, Y. B. Liu, Zhen-An Liu, Zhiqing Liu, Y. F. Long, Xinchou Lou, F. X. Lu, H. J. Lu, J. D. Lu, Junguang Lu, X. L. Lu, Y. Lu, Yunpeng Lu, Chenglin Luo, M. X. Luo, P. W. Luo, Tao Luo, X. L. Luo, S. Lusso, Xiao-Rui Lyu, Fengcai Ma, Hailong Ma, Lianliang Ma, M. M. Ma, Qiumei Ma, Runqiu Ma, R. T. Ma, X. N. Ma, X. X. Ma, Xiaoyan Ma, Y. M. Ma, Frank E. Maas, Marco Maggiora, Stephan Maldaner, Sneha Malde, Qadeer Afzal Malik, Alessio Mangoni, Yajun Mao, Zepu Mao, Simonetta Marcello, Z. X. Meng, Johannes Gerhardus Messchendorp, Giulio Mezzadri, T. J. Min, Ryan Edward Mitchell, Xiaohu Mo, Y. J. Mo, Nikolai Yu. Muchnoi, H. Muramatsu, Simon Nakhoul, Yury Nefedov, Frank Nerling, Ivan Borisovich Nikolaev, Z. Ning, Shabana Nisar, Stephen L. Olsen, Qun Ouyang, Simone Pacetti, X. Pan, Y. Pan, A. Pathak, P. Patteri, Marc Pelizäus, H. P. Peng, Klaus Peters, J. Pettersson, J. L. Ping, R. G. Ping, A. Pitka, Ronald Poling, Vindhyawasini Prasad, H. Qi, H. R. Qi, Ming Qi, Tianyu Qi, S. Qian, W.-B. Qian, Z. Qian, Congfeng Qiao, L. Q. Qin, Xiaoping Qin, X. S. Qin, Zhonghua Qin, Jinfa Qiu, S. Q. Qu, K. H. Rashid, Krishnakumar Ravindran, Christoph Florian Redmer, Angelo Rivetti, Viktor Rodin, Manuel Dionisio Da Rocha Rolo, Gang Rong, Christoph Rosner, Marcel Andre Rump, Andrei V. Sarantsev, M. Savrié, Yasemin Schelhaas, Claudius Schnier, Karin Schönning, D. C. Shan, Wei Shan, Xinyu Shan, M. Shao, Chengping Shen, P. X. Shen, X. Y. Shen, Huangchao Shi, Rongsheng Shi, X. Shi, Xiaodong Shi, J. J. Song, Q. Q. Song, Weimin Song, Yunxuan Song, Stefano Sosio, Stefano Spataro, F. F. Sui, Gongxing Sun, J. F. Sun, Liang Sun, S. S. Sun, T. Sun, Wenyu Sun, Y. J. Sun, Y. K. Sun, Y. Z. Sun, Z. T. Sun, Y. H. Tan, Yaxing Tan, C. J. Tang, G. Y. Tang, J. Tang, Viktor Thoren, B. Tsednee, Ismail Uman, B. Wang, B. L. Wang, Chengwei Wang, D. Y. Wang, H. P. Wang, K. Wang, Liangliang Wang, M. Wang, M. Z. Wang, Meng Wang, W. H. Wang, Weiping Wang, X. Wang, Xiongfei Wang, X. L. Wang, Y. Wang, Y. Wang, Y. D. Wang, Y. F. Wang, Y. Q. Wang, Z. Wang, Z. Y. Wang, Ziyi Wang, Zongyuan Wang, D. H. Wei, P. Weidenkaff, Frederik Weidner, Shuopin Wen, D. J. White, Ulrich Wiedner, Guy Wilkinson, Magnus Wolke, Leonard Wollenberg, Jinfei Wu, Linghui Wu, Lianjin Wu, Xiao Wu, Z. Wu, L. Xia, Hao Xiao, S. Y. Xiao, Y. J. Xiao, Zhenjun Xiao, X. H. Xie, Y. G. Xie, Y. H. Xie, T. Y. Xing, X. A. Xiong, Guofa Xu, J. J. Xu, Q. J. Xu, Wei Xu, Xinping Xu, Liang Yan, Liang Yan, W. B. Yan, W. C. Yan, Xu Yan, H. J. Yang, Hongxun Yang, L. Yang, R. X. Yang, S. L. Yang, Y. H. Yang, Yongxu Yang, Yifan Yang, Zhi Yang, M. Ye, Minghan Ye, J. H. Yin, Z. Y. You, Boxiang Yu, C. X. Yu, G. Yu, J. S. Yu, T. Yu, Chang-Zheng Yuan, W. Yuan, X. Q. Yuan, Y. Yuan, Z. Y. Yuan, C. X. Yue, A. Yuncu, A. A. Zafar, Y. Zeng, B. X. Zhang, Guangyi Zhang, H. H. Zhang, Hongyu Zhang, J. L. Zhang, Jingqing Zhang, Jiawei Zhang, Jianyong Zhang, J. Z. Zhang, Jianyu Zhang, Jiawei Zhang, L. Zhang, Lei Zhang, S. Zhang, S. F. Zhang, T. J. Zhang, X. Y. Zhang, Y. Zhang, Y. H. Zhang, Yateng Zhang, Yan Zhang, Yao Zhang, Yi Zhang, Z. H. Zhang, Z. Y. Zhang, G. Zhao, J. Zhao, Jingyi Zhao, J. Z. Zhao, Lei Zhao, Ling Zhao, Ming-Gang Zhao, Q. Zhao, Shujun Zhao, Yubin Zhao, Y. X. Zhao Zhao, Zhengguo Zhao, Alexey Zhemchugov, Bo Zheng, Jianping Zheng, Y. Zheng, Y. H. Zheng, B. Zhong, C. Zhong, L. P. Zhou, Q. Zhou, X. Zhou, X. K. Zhou, X. R. Zhou, A. N. Zhu, J. Zhu, K. Zhu, Kejun Zhu, S. H. Zhu, W. J. Zhu, X. L. Zhu, Y. C. Zhu, Zian Zhu, B. S. Zou, Jiaheng Zou

• From 1310.6×106 J/ψ and 448.1×106 ψ(3686) events collected with the BESIII experiment, we report the first observation of Σ+ and Σ¯− spin polarization in e+e−→J/ψ(ψ(3686))→Σ+Σ¯− decays. The relative phases of the form factors ΔΦ have been measured to be (−15.5±0.7±0.5)∘ and (21.7±4.0±0.8)∘ with J/ψ and ψ(3686) data, respectively. The non-zero value of ΔΦ allows for a direct and simultaneous measurement of the decay asymmetry parameters of Σ+→pπ0 (α0=−0.998±0.037±0.009) and Σ¯−→p¯π0 (α¯0=0.990±0.037±0.011), the latter value being determined for the first time. The average decay asymmetry, (α0−α¯0)/2, is calculated to be −0.994±0.004±0.002. The CP asymmetry ACP,Σ=(α0+α¯0)/(α0−α¯0)=−0.004±0.037±0.010 is extracted for the first time, and is found to be consistent with CP conservation.