Open Access

Medina Ablikim, Mikhail N. Achasov, Patrik Adlarson, Samer Ahmed, Malte Albrecht, Riccardo Aliberti, Antonio Amoroso, M. R. An, Q. An, X. H. Bai, Yu Bai, Olga Bakina, Rinaldo Baldini Ferroli, Ilaria Balossino, Yong Ban, Khurelbaatar Begzsuren, Niklaus Berger, Monica Bertani, Diego Bettoni, Fabrizio Bianchi, Jacek Biernat, Johannes Bloms, Alberto Bortone, Igor R. Boyko, Roy A. Briere, H. Cai, X. Cai, Alessandro Calcaterra, G. F. Cao, N. 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, Z. J. Chen, W. S. Cheng, Gianluigi Cibinetto, Fabio Cossio, X. F. Cui, Hongliang 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, X. Dong, Shuxian Du, Y. L. Fan, J. Fang, Shuangshi Fang, Y. Fang, Riccardo Farinelli, Luciano Fava, Florian Feldbauer, Giulietto Felici, C. Q. Feng, J. H. Feng, Miriam Fritsch, Chengdong Fu, Y. Gao, Y. Gao, Y. Gao, Y. G. Gao, I. Garzia, P. T. Ge, C. Geng, Evelina Gersabeck, A. 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, Alexey Guskov, T. T. Han, W. Y. Han, J. Hansson, Xiqing Hao, F. A. Harris, Nils Hüsken, K. L. He, Fritz-Herbert Heinsius, C. H. Heinz, T. Held, Yuekun Heng, Christoph Herold, 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, Y. P. Huang, Z. Huang, Tahir Hussain, Walter Ikegami Andersson, William Imoehl, M. Irshad, S. Jaeger, S. Janchiv, Quan Ji, Qingping Ji, X. B. Ji, X. L. Ji, Y. Y. Ji, H. B. Jiang, Xiaoshan Jiang, J. B. Jiao, Z. Jiao, Shan Jin, Y. Jin, Tord Johansson, Nasser Kalantar-Nayestanaki, X. S. Kang, Rosa Kappert, Myroslav O. Kavatsyuk, B. C. Ke, I. K. Keshk, Alfons Khoukaz, P. Kiese, R. Kiuchi, Ralf Kliemt, L. Koch, Onur Bugra Kolcu, Bertram Kopf, M. Kuemmel, Meike Küßner, Andrzej Kupsc, M. G. Kurth, Wolfgang Kühn, John Jake Lane, Jens Sören Lange, Paul Larin, Anita Lavania, Lia Lavezzi, Z. H. Lei, H. Leithoff, Max Lellmann, Thomas Lenz, C. Li, C. H. Li, Cheng Li, D. M. Li, F. Li, G. Li, H. Li, H. Li, Haibo Li, H. J. Li, H. J. Li, J. L. Li, J. Q. Li, J. S. Li, Ke Li, L. K. Li, Lei Li, P. R. Li, S. Y. Li, Weidong Li, Weiguo Li, X. H. Li, X. L. Li, Xiaoyu Li, Z. Y. Li, H. Liang, H. Liang, H. Liang, Y. F. Liang, Y. T. Liang, G. R. Liao, L. Z. Liao, J. Libby, C. X. Lin, B. J. Liu, C. X. Liu, D. Liu, Fu-Hu Liu, Fang Liu, Feng Liu, H. B. Liu, H. M. Liu, Huanhuan Liu, Huihui Liu, J. B. Liu, J. L. Liu, J. Y. Liu, K. Liu, K. Y. Liu, Ke Liu, L. Liu, M. H. Liu, P. L. Liu, Q. Liu, Q. Liu, S. B. Liu, Shuai Liu, T. Liu, W. M. Liu, X. Liu, Y. Liu, Y. B. Liu, Zhen-An Liu, Z. Q. Liu, Xinchou Lou, F. X. Lu, 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, T. Luo, X. L. Luo, S. Lusso, Xiao-Rui Lyu, Fengcai Ma, H. L. Ma, Lianliang Ma, M. M. Ma, Qiumei Ma, R. Q. Ma, R. T. Ma, X. X. Ma, Xiaoyan 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. L. Ping, R. G. Ping, Ronald Poling, Vindhyawasini Prasad, H. Qi, H. R. Qi, K. H. Qi, Ming Qi, T. Y. Qi, T. Y. Qi, S. Qian, W. B. Qian, Z. Qian, Congfeng Qiao, L. Q. Qin, X. P. 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, H. S. Sang, Andrei V. Sarantsev, Yasemin Schelhaas, Claudius Schnier, Karin Schönning, Marco Scodeggio, D. C. Shan, Wei Shan, Xinyu Shan, J. F. Shangguan, M. Shao, C. P. Shen, P. X. Shen, X. Y. Shen, H. C. Shi, R. S. Shi, X. Shi, X. D. Shi, J. J. Song, W. M. Song, Y. X. Song, Stefano Sosio, Stefano Spataro, K. X. Su, P. P. Su, F. F. Sui, Gongxing Sun, H. K. Sun, J. F. Sun, L. Sun, S. S. Sun, T. Sun, W. Y. Sun, W. Y. Sun, X. Sun, Y. J. Sun, Y. K. Sun, Y. Z. Sun, Z. T. Sun, Y. H. Tan, Y. X. Tan, C. J. Tang, G. Y. Tang, J. Tang, J. X. Teng, Viktor Thoren, Y. T. Tian, Ismail Uman, B. Wang, C. W. Wang, D. Y. Wang, H. J. Wang, H. P. Wang, K. Wang, L. L. Wang, M. Wang, M. Z. Wang, Meng Wang, W. Wang, W. H. Wang, W. P. Wang, X. Wang, X. F. Wang, X. L. Wang, Y. Wang, Y. Wang, Y. D. Wang, Y. F. Wang, Y. Q. Wang, Y. Y. Wang, Z. Wang, Zongyuan Wang, Ziyi Wang, Zongyuan Wang, D. H. Wei, P. Weidenkaff, Frederik Weidner, Shuopin Wen, D. J. White, Ulrich Wiedner, G. Wilkinson, Magnus Wolke, Leonard Wollenberg, J. F. Wu, L. H. Wu, L. J. Wu, X. Wu, Z. Wu, Lei Xia, H. Xiao, S. Y. Xiao, Zhenjun Xiao, X. H. Xie, Y. G. Xie, Y. H. Xie, T. Y. Xing, Guofa Xu, Q. J. Xu, W. Xu, Xinping Xu, Y. C. Xu, F. Yan, L. Yan, W. B. Yan, W. C. Yan, Xu Yan, H. J. Yang, Hongxun Yang, L. Yang, S. L. 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, L. Yuan, X. Q. Yuan, Y. Yuan, Z. Y. Yuan, C. X. Yue, A. A. Zafar, Y. Zeng, B. X. Zhang, Guangyi Zhang, H. Zhang, H. H. Zhang, H. H. Zhang, Hongyu Zhang, J. J. Zhang, J. L. Zhang, J. Q. Zhang, J. W. Zhang, Jianyong Zhang, J. Z. Zhang, Jianyu Zhang, Jiawei Zhang, L. M. Zhang, L. Q. Zhang, Lei Zhang, S. Zhang, S. F. Zhang, Shulei Zhang, X. D. Zhang, X. Y. Zhang, Y. Zhang, Y. H. Zhang, Y. T. Zhang, Yan Zhang, Yao Zhang, Yi Zhang, Z. H. Zhang, Z. Y. Zhang, G. Zhao, J. Zhao, J. Y. Zhao, J. Z. Zhao, Lei Zhao, Ling Zhao, Ming-Gang Zhao, Q. Zhao, Shujun Zhao, Yubin Zhao, Y. X. Zhao, Zhengguo Zhao, Alexey Zhemchugov, B. 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, X. Y. Zhou, A. N. Zhu, J. Zhu, K. Zhu, Kejun Zhu, S. H. Zhu, T. J. Zhu, W. J. Zhu, W. J. Zhu, Y. C. Zhu, Zian Zhu, B. S. Zou, Jiaheng Zou

• Though immensely successful, the standard model of particle physics does not offer any explanation as to why our Universe contains so much more matter than antimatter. A key to a dynamically generated matter–antimatter asymmetry is the existence of processes that violate the combined charge conjugation and parity (CP) symmetry1. As such, precision tests of CP symmetry may be used to search for physics beyond the standard model. However, hadrons decay through an interplay of strong and weak processes, quantified in terms of relative phases between the amplitudes. Although previous experiments constructed CP observables that depend on both strong and weak phases, we present an approach where sequential two-body decays of entangled multi-strange baryon–antibaryon pairs provide a separation between these phases. Our method, exploiting spin entanglement between the double-strange Ξ− baryon and its antiparticle2 Ξ¯+ , has enabled a direct determination of the weak-phase difference, (ξP − ξS) = (1.2 ± 3.4 ± 0.8) × 10−2 rad. Furthermore, three independent CP observables can be constructed from our measured parameters. The precision in the estimated parameters for a given data sample size is several orders of magnitude greater than achieved with previous methods3. Finally, we provide an independent measurement of the recently debated Λ decay parameter αΛ (refs. 4,5). The ΛΛ¯ asymmetry is in agreement with and compatible in precision to the most precise previous measurement.