Letter
Open Access

Evidence of transverse polarization of the $Ξ^{0}$ hyperon in $ψ (3686) \to Ξ^{0} {\bar{Ξ}}^{0}$

M. Ablikim ¹, M. N. Achasov ^4,c, P. Adlarson ⁸¹, X. C. Ai ⁸⁶, R. Aliberti ³⁸, A. Amoroso ^80a,80c, Q. An^77,63,a, Y. Bai ⁶¹, O. Bakina ³⁹ et al. (BESIII Collaboration)

O. Bakina ³⁹, Y. Ban ^49,h, H.-R. Bao ⁶⁹, V. Batozskaya ^1,47, K. Begzsuren³⁵, N. Berger ³⁸, M. Berlowski ⁴⁷, M. B. Bertani ^30a, D. Bettoni ^31a, F. Bianchi ^80a,80c, E. Bianco^80a,80c, A. Bortone ^80a,80c, I. Boyko ³⁹, R. A. Briere ⁵, A. Brueggemann ⁷⁴, H. Cai ⁸², M. H. Cai ^41,k,l, X. Cai ^1,63, A. Calcaterra ^30a, G. F. Cao ^1,69, N. Cao ^1,69, S. A. Cetin ^67a, X. Y. Chai ^49,h, J. F. Chang ^1,63, T. T. Chang ⁴⁶, G. R. Che ⁴⁶, Y. Z. Che ^1,63,69, C. H. Chen ¹⁰, Chao Chen ⁵⁹, G. Chen ¹, H. S. Chen ^1,69, H. Y. Chen ²¹, M. L. Chen ^1,63,69, S. J. Chen ⁴⁵, S. M. Chen ⁶⁶, T. Chen ^1,69, X. R. Chen ^34,69, X. T. Chen ^1,69, X. Y. Chen ^12,g, Y. B. Chen ^1,63, Y. Q. Chen ¹⁶, Z. K. Chen ⁶⁴, J. C. Cheng ⁴⁸, L. N. Cheng ⁴⁶, S. K. Choi ¹¹, X. Chu ^12,g, G. Cibinetto ^31a, F. Cossio ^80c, J. Cottee-Meldrum ⁶⁸, H. L. Dai ^1,63, J. P. Dai ⁸⁴, X. C. Dai ⁶⁶, A. Dbeyssi¹⁹, R. E. de Boer ³, D. Dedovich ³⁹, C. Q. Deng ⁷⁸, Z. Y. Deng ¹, A. Denig ³⁸, I. Denisenko ³⁹, M. Destefanis ^80a,80c, F. De Mori ^80a,80c, X. X. Ding ^49,h, Y. Ding ⁴³, Y. X. Ding ³², J. Dong ^1,63, L. Y. Dong ^1,69, M. Y. Dong ^1,63,69, X. Dong ⁸², M. C. Du ¹, S. X. Du ⁸⁶, S. X. Du ^12,g, X. L. Du ⁸⁶, Y. Y. Duan ⁵⁹, Z. H. Duan ⁴⁵, P. Egorov ^39,b, G. F. Fan ⁴⁵, J. J. Fan ²⁰, Y. H. Fan ⁴⁸, J. Fang ^1,63, J. Fang ⁶⁴, S. S. Fang ^1,69, W. X. Fang ¹, Y. Q. Fang^1,63,a, L. Fava ^80b,80c, F. Feldbauer ³, G. Felici ^30a, C. Q. Feng ^77,63, J. H. Feng ¹⁶, L. Feng ^41,k,l, Q. X. Feng ^41,k,l, Y. T. Feng ^77,63, M. Fritsch ³, C. D. Fu ¹, J. L. Fu ⁶⁹, Y. W. Fu ^1,69, H. Gao ⁶⁹, Y. Gao ^77,63, Y. N. Gao ^49,h, Y. N. Gao ²⁰, Y. Y. Gao ³², Z. Gao ⁴⁶, S. Garbolino ^80c, I. Garzia ^31a,31b, L. Ge ⁶¹, P. T. Ge ²⁰, Z. W. Ge ⁴⁵, C. Geng ⁶⁴, E. M. Gersabeck ⁷³, A. Gilman ⁷⁵, K. Goetzen ¹³, J. D. Gong ³⁷, L. Gong ⁴³, W. X. Gong ^1,63, W. Gradl ³⁸, S. Gramigna ^31a,31b, M. Greco ^80a,80c, M. D. Gu ⁵⁴, M. H. Gu ^1,63, C. Y. Guan ^1,69, A. Q. Guo ³⁴, J. N. Guo ^12,g, L. B. Guo ⁴⁴, M. J. Guo ⁵³, R. P. Guo ⁵², X. Guo ⁵³, Y. P. Guo ^12,g, A. Guskov ^39,b, J. Gutierrez ²⁹, T. T. Han ¹, F. Hanisch ³, K. D. Hao ^77,63, X. Q. Hao ²⁰, F. A. Harris ⁷¹, C. Z. He ^49,h, K. L. He ^1,69, F. H. Heinsius ³, C. H. Heinz ³⁸, Y. K. Heng ^1,63,69, C. Herold ⁶⁵, P. C. Hong ³⁷, G. Y. Hou ^1,69, X. T. Hou ^1,69, Y. R. Hou ⁶⁹, Z. L. Hou ¹, H. M. Hu ^1,69, J. F. Hu ^60,j, Q. P. Hu ^77,63, S. L. Hu ^12,g, T. Hu ^1,63,69, Y. Hu ¹, Z. M. Hu ⁶⁴, G. S. Huang ^77,63, K. X. Huang ⁶⁴, L. Q. Huang ^34,69, P. Huang ⁴⁵, X. T. Huang ⁵³, Y. P. Huang ¹, Y. S. Huang ⁶⁴, T. Hussain ⁷⁹, N. Hüsken ³⁸, N. in der Wiesche ⁷⁴, J. Jackson ²⁹, Q. Ji ¹, Q. P. Ji ²⁰, W. Ji ^1,69, X. B. Ji ^1,69, X. L. Ji ^1,63, X. Q. Jia ⁵³, Z. K. Jia ^77,63, D. Jiang ^1,69, H. B. Jiang ⁸², P. C. Jiang ^49,h, S. J. Jiang ¹⁰, X. S. Jiang ^1,63,69, Y. Jiang ⁶⁹, J. B. Jiao ⁵³, J. K. Jiao ³⁷, Z. Jiao ²⁵, S. Jin ⁴⁵, Y. Jin ⁷², M. Q. Jing ^1,69, X. M. Jing ⁶⁹, T. Johansson ⁸¹, S. Kabana ³⁶, N. Kalantar-Nayestanaki⁷⁰, X. L. Kang ¹⁰, X. S. Kang ⁴³, M. Kavatsyuk ⁷⁰, B. C. Ke ⁸⁶, V. Khachatryan ²⁹, A. Khoukaz ⁷⁴, O. B. Kolcu ^67a, B. Kopf ³, L. Kröger ⁷⁴, M. Kuessner ³, X. Kui ^1,69, N. Kumar ²⁸, A. Kupsc ^47,81, W. Kühn ⁴⁰, Q. Lan ⁷⁸, W. N. Lan ²⁰, T. T. Lei ^77,63, M. Lellmann ³⁸, T. Lenz ³⁸, C. Li ⁵⁰, C. Li ⁴⁶, C. H. Li ⁴⁴, C. K. Li ²¹, D. M. Li ⁸⁶, F. Li ^1,63, G. Li ¹, H. B. Li ^1,69, H. J. Li ²⁰, H. L. Li ⁸⁶, H. N. Li ^60,j, Hui Li ⁴⁶, J. R. Li ⁶⁶, J. S. Li ⁶⁴, J. W. Li ⁵³, K. Li ¹, K. L. Li ^41,k,l, L. J. Li ^1,69, Lei Li ⁵¹, M. H. Li ⁴⁶, M. R. Li ^1,69, P. L. Li ⁶⁹, P. R. Li ^41,k,l, Q. M. Li ^1,69, Q. X. Li ⁵³, R. Li ^18,34, S. X. Li ¹², Shanshan Li ^27,i, T. Li ⁵³, T. Y. Li ⁴⁶, W. D. Li ^1,69, W. G. Li ^1,b, X. Li ^1,69, X. H. Li ^77,63, X. K. Li ^49,h, X. L. Li ⁵³, X. Y. Li ^1,9, X. Z. Li ⁶⁴, Y. Li ²⁰, Y. G. Li ^49,h, Y. P. Li ³⁷, Z. H. Li ⁴¹, Z. J. Li ⁶⁴, Z. X. Li ⁴⁶, Z. Y. Li ⁸⁴, C. Liang ⁴⁵, H. Liang ^77,63, Y. F. Liang ⁵⁸, Y. T. Liang ^34,69, G. R. Liao ¹⁴, L. B. Liao ⁶⁴, M. H. Liao ⁶⁴, Y. P. Liao ^1,69, J. Libby ²⁸, A. Limphirat ⁶⁵, D. X. Lin ^34,69, L. Q. Lin ⁴², T. Lin ¹, B. J. Liu ¹, B. X. Liu ⁸², C. X. Liu ¹, F. Liu ¹, F. H. Liu ⁵⁷, Feng Liu ⁶, G. M. Liu ^60,j, H. Liu ^41,k,l, H. B. Liu ¹⁵, H. M. Liu ^1,69, Huihui Liu ²², J. B. Liu ^77,63, J. J. Liu ²¹, K. Liu ^41,k,l, K. Liu ⁷⁸, K. Y. Liu ⁴³, Ke Liu ²³, L. Liu ⁴¹, L. C. Liu ⁴⁶, Lu Liu ⁴⁶, M. H. Liu ³⁷, P. L. Liu ¹, Q. Liu ⁶⁹, S. B. Liu ^77,63, W. M. Liu ^77,63, W. T. Liu ⁴², X. Liu ^41,k,l, X. K. Liu ^41,k,l, X. L. Liu ^12,g, X. Y. Liu ⁸², Y. Liu ^41,k,l, Y. Liu ⁸⁶, Y. B. Liu ⁴⁶, Z. A. Liu ^1,63,69, Z. D. Liu ¹⁰, Z. Q. Liu ⁵³, Z. Y. Liu ⁴¹, X. C. Lou ^1,63,69, H. J. Lu ²⁵, J. G. Lu ^1,63, X. L. Lu ¹⁶, Y. Lu ⁷, Y. H. Lu ^1,69, Y. P. Lu ^1,63, Z. H. Lu ^1,69, C. L. Luo ⁴⁴, J. R. Luo ⁶⁴, J. S. Luo ^1,69, M. X. Luo⁸⁵, T. Luo ^12,g, X. L. Luo ^1,63, Z. Y. Lv ²³, X. R. Lyu ^69,o, Y. F. Lyu ⁴⁶, Y. H. Lyu ⁸⁶, F. C. Ma ⁴³, H. L. Ma ¹, Heng Ma ^27,i, J. L. Ma ^1,69, L. L. Ma ⁵³, L. R. Ma ⁷², Q. M. Ma ¹, R. Q. Ma ^1,69, R. Y. Ma ²⁰, T. Ma ^77,63, X. T. Ma ^1,69, X. Y. Ma ^1,63, Y. M. Ma ³⁴, F. E. Maas ¹⁹, I. MacKay ⁷⁵, M. Maggiora ^80a,80c, S. Malde ⁷⁵, Q. A. Malik ⁷⁹, H. X. Mao ^41,k,l, Y. J. Mao ^49,h, Z. P. Mao ¹, S. Marcello ^80a,80c, A. Marshall ⁶⁸, F. M. Melendi ^31a,31b, Y. H. Meng ⁶⁹, Z. X. Meng ⁷², G. Mezzadri ^31a, H. Miao ^1,69, T. J. Min ⁴⁵, R. E. Mitchell ²⁹, X. H. Mo ^1,63,69, B. Moses ²⁹, N. Yu. Muchnoi ^4,c, J. Muskalla ³⁸, Y. Nefedov ³⁹, F. Nerling ^19,e, H. Neuwirth ⁷⁴, Z. Ning ^1,63, S. Nisar³³, Q. L. Niu ^41,k,l, W. D. Niu ^12,g, Y. Niu ⁵³, C. Normand ⁶⁸, S. L. Olsen ^11,69, Q. Ouyang ^1,63,69, S. Pacetti ^30b,30c, X. Pan ⁵⁹, Y. Pan ⁶¹, A. Pathak ¹¹, Y. P. Pei ^77,63, M. Pelizaeus ³, H. P. Peng ^77,63, X. J. Peng ^41,k,l, Y. Y. Peng ^41,k,l, K. Peters ^13,e, K. Petridis ⁶⁸, J. L. Ping ⁴⁴, R. G. Ping ^1,69, S. Plura ³⁸, V. Prasad ³⁷, F. Z. Qi ¹, H. R. Qi ⁶⁶, M. Qi ⁴⁵, S. Qian ^1,63, W. B. Qian ⁶⁹, C. F. Qiao ⁶⁹, J. H. Qiao ²⁰, J. J. Qin ⁷⁸, J. L. Qin ⁵⁹, L. Q. Qin ¹⁴, L. Y. Qin ^77,63, P. B. Qin ⁷⁸, X. P. Qin ⁴², X. S. Qin ⁵³, Z. H. Qin ^1,63, J. F. Qiu ¹, Z. H. Qu ⁷⁸, J. Rademacker ⁶⁸, C. F. Redmer ³⁸, A. Rivetti ^80c, M. Rolo ^80c, G. Rong ^1,69, S. S. Rong ^1,69, F. Rosini ^30b,30c, Ch. Rosner ¹⁹, M. Q. Ruan ^1,63, N. Salone ^47,p, A. Sarantsev ^39,d, Y. Schelhaas ³⁸, K. Schoenning ⁸¹, M. Scodeggio ^31a, W. Shan ²⁶, X. Y. Shan ^77,63, Z. J. Shang ^41,k,l, J. F. Shangguan ¹⁷, L. G. Shao ^1,69, M. Shao ^77,63, C. P. Shen ^12,g, H. F. Shen ^1,9, W. H. Shen ⁶⁹, X. Y. Shen ^1,69, B. A. Shi ⁶⁹, H. Shi ^77,63, J. L. Shi ^8,q, J. Y. Shi ¹, S. Y. Shi ⁷⁸, X. Shi ^1,63, H. L. Song ^77,63, J. J. Song ²⁰, M. H. Song ⁴¹, T. Z. Song ⁶⁴, W. M. Song ³⁷, Y. X. Song ^49,h,m, Zirong Song ^27,i, S. Sosio ^80a,80c, S. Spataro ^80a,80c, S. Stansilaus⁷⁵, F. Stieler ³⁸, S. S. Su⁴³, G. B. Sun ⁸², G. X. Sun ¹, H. Sun ⁶⁹, H. K. Sun ¹, J. F. Sun ²⁰, K. Sun ⁶⁶, L. Sun ⁸², R. Sun ⁷⁷, S. S. Sun ^1,69, T. Sun ^55,f, W. Y. Sun ⁵⁴, Y. C. Sun ⁸², Y. H. Sun ³², Y. J. Sun ^77,63, Y. Z. Sun ¹, Z. Q. Sun ^1,69, Z. T. Sun ⁵³, C. J. Tang⁵⁸, G. Y. Tang ¹, J. Tang ⁶⁴, J. J. Tang ^77,63, L. F. Tang ⁴², Y. A. Tang ⁸², L. Y. Tao ⁷⁸, M. Tat ⁷⁵, J. X. Teng ^77,63, J. Y. Tian ^77,63, W. H. Tian ⁶⁴, Y. Tian ³⁴, Z. F. Tian ⁸², I. Uman ^67b, B. Wang ¹, B. Wang ⁶⁴, Bo Wang ^77,63, C. Wang ^41,k,l, C. Wang ²⁰, Cong Wang ²³, D. Y. Wang ^49,h, H. J. Wang ^41,k,l, J. Wang ¹⁰, J. J. Wang ⁸², J. P. Wang ⁵³, K. Wang ^1,63, L. L. Wang ¹, L. W. Wang ³⁷, M. Wang ⁵³, M. Wang ^77,63, N. Y. Wang ⁶⁹, S. Wang ^41,k,l, Shun Wang ⁶², T. Wang ^12,g, T. J. Wang ⁴⁶, W. Wang ⁶⁴, W. P. Wang ³⁸, X. Wang ^49,h, X. F. Wang ^41,k,l, X. L. Wang ^12,g, X. N. Wang ^1,69, Xin Wang ^27,i, Y. Wang ¹, Y. D. Wang ⁴⁸, Y. F. Wang ^1,9,69, Y. H. Wang ^41,k,l, Y. J. Wang ^77,63, Y. L. Wang ²⁰, Y. N. Wang ⁴⁸, Y. N. Wang ⁸², Yaqian Wang ¹⁸, Yi Wang ⁶⁶, Yuan Wang ^18,34, Z. Wang ^1,63, Z. Wang ⁴⁶, Z. L. Wang ², Z. Q. Wang ^12,g, Z. Y. Wang ^1,69, Ziyi Wang ⁶⁹, D. Wei ⁴⁶, D. H. Wei ¹⁴, H. R. Wei ⁴⁶, F. Weidner ⁷⁴, S. P. Wen ¹, U. Wiedner ³, G. Wilkinson ⁷⁵, M. Wolke⁸¹, J. F. Wu ^1,9, L. H. Wu ¹, L. J. Wu ²⁰, Lianjie Wu ²⁰, S. G. Wu ^1,69, S. M. Wu ⁶⁹, X. Wu ^12,g, Y. J. Wu ³⁴, Z. Wu ^1,63, L. Xia ^77,63, B. H. Xiang ^1,69, D. Xiao ^41,k,l, G. Y. Xiao ⁴⁵, H. Xiao ⁷⁸, Y. L. Xiao ^12,g, Z. J. Xiao ⁴⁴, C. Xie ⁴⁵, K. J. Xie ^1,69, Y. Xie ⁵³, Y. G. Xie ^1,63, Y. H. Xie ⁶, Z. P. Xie ^77,63, T. Y. Xing ^1,69, C. J. Xu ⁶⁴, G. F. Xu ¹, H. Y. Xu ², M. Xu ^77,63, Q. J. Xu ¹⁷, Q. N. Xu ³², T. D. Xu ⁷⁸, X. P. Xu ⁵⁹, Y. Xu ^12,g, Y. C. Xu ⁸³, Z. S. Xu ⁶⁹, F. Yan ²⁴, L. Yan ^12,g, W. B. Yan ^77,63, W. C. Yan ⁸⁶, W. H. Yan ⁶, W. P. Yan ²⁰, X. Q. Yan ^1,69, H. J. Yang ^55,f, H. L. Yang ³⁷, H. X. Yang ¹, J. H. Yang ⁴⁵, R. J. Yang ²⁰, Y. Yang ^12,g, Y. H. Yang ⁴⁵, Y. Q. Yang ¹⁰, Y. Z. Yang ²⁰, Z. P. Yao ⁵³, M. Ye ^1,63, M. H. Ye^9,a, Z. J. Ye ^60,j, Junhao Yin ⁴⁶, Z. Y. You ⁶⁴, B. X. Yu ^1,63,69, C. X. Yu ⁴⁶, G. Yu ¹³, J. S. Yu ^27,i, L. W. Yu ^12,g, T. Yu ⁷⁸, X. D. Yu ^49,h, Y. C. Yu ⁸⁶, Y. C. Yu ⁴¹, C. Z. Yuan ^1,69, H. Yuan ^1,69, J. Yuan ³⁷, J. Yuan ⁴⁸, L. Yuan ², M. K. Yuan ^12,g, S. H. Yuan ⁷⁸, Y. Yuan ^1,69, C. X. Yue ⁴², Ying Yue ²⁰, A. A. Zafar ⁷⁹, F. R. Zeng ⁵³, S. H. Zeng ⁶⁸, X. Zeng ^12,g, Y. J. Zeng ⁶⁴, Y. J. Zeng ^1,69, Y. C. Zhai ⁵³, Y. H. Zhan ⁶⁴, S. N. Zhang⁷⁵, B. L. Zhang ^1,69, B. X. Zhang ^1,a, D. H. Zhang ⁴⁶, G. Y. Zhang ²⁰, G. Y. Zhang ^1,69, H. Zhang ^77,63, H. Zhang ⁸⁶, H. C. Zhang ^1,63,69, H. H. Zhang ⁶⁴, H. Q. Zhang ^1,63,69, H. R. Zhang ^77,63, H. Y. Zhang ^1,63, J. Zhang ⁶⁴, J. J. Zhang ⁵⁶, J. L. Zhang ²¹, J. Q. Zhang ⁴⁴, J. S. Zhang ^12,g, J. W. Zhang ^1,63,69, J. X. Zhang ^41,k,l, J. Y. Zhang ¹, J. Z. Zhang ^1,69, Jianyu Zhang ⁶⁹, L. M. Zhang ⁶⁶, Lei Zhang ⁴⁵, N. Zhang ⁸⁶, P. Zhang ^1,9, Q. Zhang ²⁰, Q. Y. Zhang ³⁷, R. Y. Zhang ^41,k,l, S. H. Zhang ^1,69, Shulei Zhang ^27,i, X. M. Zhang ¹, X. Y. Zhang ⁵³, Y. Zhang ¹, Y. Zhang ⁷⁸, Y. T. Zhang ⁸⁶, Y. H. Zhang ^1,63, Y. P. Zhang ^77,63, Z. D. Zhang ¹, Z. H. Zhang ¹, Z. L. Zhang ³⁷, Z. L. Zhang ⁵⁹, Z. X. Zhang ²⁰, Z. Y. Zhang ⁸², Z. Y. Zhang ⁴⁶, Z. Z. Zhang ⁴⁸, Zh. Zh. Zhang ²⁰, G. Zhao ¹, J. Y. Zhao ^1,69, J. Z. Zhao ^1,63, L. Zhao ¹, L. Zhao ^77,63, M. G. Zhao ⁴⁶, S. J. Zhao ⁸⁶, Y. B. Zhao ^1,63, Y. L. Zhao ⁵⁹, Y. X. Zhao ^34,69, Z. G. Zhao ^77,63, A. Zhemchugov ^39,b, B. Zheng ⁷⁸, B. M. Zheng ³⁷, J. P. Zheng ^1,63, W. J. Zheng ^1,69, X. R. Zheng ²⁰, Y. H. Zheng ^69,o, B. Zhong ⁴⁴, C. Zhong ²⁰, H. Zhou ^38,53,n, J. Q. Zhou ³⁷, S. Zhou ⁶, X. Zhou ⁸², X. K. Zhou ⁶, X. R. Zhou ^77,63, X. Y. Zhou ⁴², Y. X. Zhou ⁸³, Y. Z. Zhou ^12,g, A. N. Zhu ⁶⁹, J. Zhu ⁴⁶, K. Zhu ¹, K. J. Zhu ^1,63,69, K. S. Zhu ^12,g, L. Zhu ³⁷, L. X. Zhu ⁶⁹, S. H. Zhu ⁷⁶, T. J. Zhu ^12,g, W. D. Zhu ^12,g, W. J. Zhu ¹, W. Z. Zhu ²⁰, Y. C. Zhu ^77,63, Z. A. Zhu ^1,69, X. Y. Zhuang ⁴⁶, J. H. Zou ¹, and J. Zu ^77,63 (BESIII Collaboration)

¹Institute of High Energy Physics, Beijing 100049, People’s Republic of China
²Beihang University, Beijing 100191, People’s Republic of China
³Bochum Ruhr-University, D-44780 Bochum, Germany
⁴Budker Institute of Nuclear Physics SB RAS (BINP), Novosibirsk 630090, Russia
⁵Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA
⁶Central China Normal University, Wuhan 430079, People’s Republic of China
⁷Central South University, Changsha 410083, People’s Republic of China
⁸Chengdu University of Technology, Chengdu 610059, People’s Republic of China
⁹China Center of Advanced Science and Technology, Beijing 100190, People’s Republic of China
¹⁰China University of Geosciences, Wuhan 430074, People’s Republic of China
¹¹Chung-Ang University, Seoul, 06974, Republic of Korea
¹²Fudan University, Shanghai 200433, People’s Republic of China
¹³GSI Helmholtzcentre for Heavy Ion Research GmbH, D-64291 Darmstadt, Germany
¹⁴Guangxi Normal University, Guilin 541004, People’s Republic of China
¹⁵Guangxi University, Nanning 530004, People’s Republic of China
¹⁶Guangxi University of Science and Technology, Liuzhou 545006, People’s Republic of China
¹⁷Hangzhou Normal University, Hangzhou 310036, People’s Republic of China
¹⁸Hebei University, Baoding 071002, People’s Republic of China
¹⁹Helmholtz Institute Mainz, Staudinger Weg 18, D-55099 Mainz, Germany
²⁰Henan Normal University, Xinxiang 453007, People’s Republic of China
²¹Henan University, Kaifeng 475004, People’s Republic of China
²²Henan University of Science and Technology, Luoyang 471003, People’s Republic of China
²³Henan University of Technology, Zhengzhou 450001, People’s Republic of China
²⁴Hengyang Normal University, Hengyang 421001, People’s Republic of China
²⁵Huangshan College, Huangshan 245000, People’s Republic of China
²⁶Hunan Normal University, Changsha 410081, People’s Republic of China
²⁷Hunan University, Changsha 410082, People’s Republic of China
²⁸Indian Institute of Technology Madras, Chennai 600036, India
²⁹Indiana University, Bloomington, Indiana 47405, USA
^30aINFN Laboratori Nazionali di Frascati, I-00044, Frascati, Italy
^30bINFN Sezione di Perugia, I-06100, Perugia, Italy
^30cUniversity of Perugia, I-06100, Perugia, Italy
^31aINFN Sezione di Ferrara, I-44122, Ferrara, Italy
^31bUniversity of Ferrara, I-44122, Ferrara, Italy
³²Inner Mongolia University, Hohhot 010021, People’s Republic of China
³³Institute of Business Administration, University Road, Karachi, 75270, Pakistan
³⁴Institute of Modern Physics, Lanzhou 730000, People’s Republic of China
³⁵Institute of Physics and Technology, Mongolian Academy of Sciences, Peace Avenue 54B, Ulaanbaatar 13330, Mongolia
³⁶Instituto de Alta Investigación, Universidad de Tarapacá, Casilla 7D, Arica 1000000, Chile
³⁷Jilin University, Changchun 130012, People’s Republic of China
³⁸Johannes Gutenberg University of Mainz, Johann-Joachim-Becher-Weg 45, D-55099 Mainz, Germany
³⁹Joint Institute for Nuclear Research, 141980 Dubna, Moscow region, Russia
⁴⁰Justus-Liebig-Universitaet Giessen, II. Physikalisches Institut, Heinrich-Buff-Ring 16, D-35392 Giessen, Germany
⁴¹Lanzhou University, Lanzhou 730000, People’s Republic of China
⁴²Liaoning Normal University, Dalian 116029, People’s Republic of China
⁴³Liaoning University, Shenyang 110036, People’s Republic of China
⁴⁴Nanjing Normal University, Nanjing 210023, People’s Republic of China
⁴⁵Nanjing University, Nanjing 210093, People’s Republic of China
⁴⁶Nankai University, Tianjin 300071, People’s Republic of China
⁴⁷National Centre for Nuclear Research, Warsaw 02-093, Poland
⁴⁸North China Electric Power University, Beijing 102206, People’s Republic of China
⁴⁹Peking University, Beijing 100871, People’s Republic of China
⁵⁰Qufu Normal University, Qufu 273165, People’s Republic of China
⁵¹Renmin University of China, Beijing 100872, People’s Republic of China
⁵²Shandong Normal University, Jinan 250014, People’s Republic of China
⁵³Shandong University, Jinan 250100, People’s Republic of China
⁵⁴Shandong University of Technology, Zibo 255000, People’s Republic of China
⁵⁵Shanghai Jiao Tong University, Shanghai 200240, People’s Republic of China
⁵⁶Shanxi Normal University, Linfen 041004, People’s Republic of China
⁵⁷Shanxi University, Taiyuan 030006, People’s Republic of China
⁵⁸Sichuan University, Chengdu 610064, People’s Republic of China
⁵⁹Soochow University, Suzhou 215006, People’s Republic of China
⁶⁰South China Normal University, Guangzhou 510006, People’s Republic of China
⁶¹Southeast University, Nanjing 211100, People’s Republic of China
⁶²Southwest University of Science and Technology, Mianyang 621010, People’s Republic of China
⁶³State Key Laboratory of Particle Detection and Electronics, Beijing 100049, Hefei 230026, People’s Republic of China
⁶⁴Sun Yat-Sen University, Guangzhou 510275, People’s Republic of China
⁶⁵Suranaree University of Technology, University Avenue 111, Nakhon Ratchasima 30000, Thailand
⁶⁶Tsinghua University, Beijing 100084, People’s Republic of China
^67aTurkish Accelerator Center Particle Factory Group, Istinye University, 34010, Istanbul, Turkey
^67bNear East University, Nicosia, North Cyprus, 99138, Mersin 10, Turkey
⁶⁸University of Bristol, H H Wills Physics Laboratory, Tyndall Avenue, Bristol, BS8 1TL, United Kingdom
⁶⁹University of Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
⁷⁰University of Groningen, NL-9747 AA Groningen, The Netherlands
⁷¹University of Hawaii, Honolulu, Hawaii 96822, USA
⁷²University of Jinan, Jinan 250022, People’s Republic of China
⁷³University of Manchester, Oxford Road, Manchester, M13 9PL, United Kingdom
⁷⁴University of Muenster, Wilhelm-Klemm-Strasse 9, 48149 Muenster, Germany
⁷⁵University of Oxford, Keble Road, Oxford OX13RH, United Kingdom
⁷⁶University of Science and Technology Liaoning, Anshan 114051, People’s Republic of China
⁷⁷University of Science and Technology of China, Hefei 230026, People’s Republic of China
⁷⁸University of South China, Hengyang 421001, People’s Republic of China
⁷⁹University of the Punjab, Lahore-54590, Pakistan
^80aUniversity of Turin and INFN, University of Turin, I-10125, Turin, Italy
^80bUniversity of Eastern Piedmont, I-15121, Alessandria, Italy
^80cINFN, I-10125, Turin, Italy
⁸¹Uppsala University, Box 516, SE-75120 Uppsala, Sweden
⁸²Wuhan University, Wuhan 430072, People’s Republic of China
⁸³Yantai University, Yantai 264005, People’s Republic of China
⁸⁴Yunnan University, Kunming 650500, People’s Republic of China
⁸⁵Zhejiang University, Hangzhou 310027, People’s Republic of China
⁸⁶Zhengzhou University, Zhengzhou 450001, People’s Republic of China

^*Full author list given at the end of the article.
^aDeceased.
^bAlso at the Moscow Institute of Physics and Technology, Moscow 141700, Russia.
^cAlso at the Novosibirsk State University, Novosibirsk, 630090, Russia.
^dAlso at the NRC “Kurchatov Institute,” PNPI, 188300, Gatchina, Russia.
^eAlso at Goethe University Frankfurt, Frankfurt am Main 60323, Germany.
^fAlso at Key Laboratory for Particle Physics, Astrophysics and Cosmology, Ministry of Education; Shanghai Key Laboratory for Particle Physics and Cosmology; Institute of Nuclear and Particle Physics, Shanghai 200240, People’s Republic of China.
^gAlso at Key Laboratory of Nuclear Physics and Ion-beam Application (MOE) and Institute of Modern Physics, Fudan University, Shanghai 200443, People’s Republic of China.
^hAlso at State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing 100871, People’s Republic of China.
ⁱAlso at School of Physics and Electronics, Hunan University, Changsha 410082, People’s Republic of China.
^jAlso at Guangdong Provincial Key Laboratory of Nuclear Science, Institute of Quantum Matter, South China Normal University, Guangzhou 510006, People’s Republic of China.
^kAlso at MOE Frontiers Science Center for Rare Isotopes, Lanzhou University, Lanzhou 730000, People’s Republic of China.
^lAlso at Lanzhou Center for Theoretical Physics, Key Laboratory of Theoretical Physics of Gansu Province, Key Laboratory of Quantum Theory and Applications of MoE, Gansu Provincial Research Center for Basic Disciplines of Quantum Physics, Lanzhou University, Lanzhou 730000, People’s Republic of China.
^mAlso at Ecole Polytechnique Federale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
ⁿAlso at Helmholtz Institute Mainz, Staudinger Weg 18, D-55099 Mainz, Germany.
^oAlso at Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou 310024, People’s Republic of China.
^pCurrently at Silesian University in Katowice, Chorzow, 41-500, Poland.
^qAlso at Applied Nuclear Technology in Geosciences Key Laboratory of Sichuan Province, Chengdu University of Technology, Chengdu 610059, People’s Republic of China.

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Phys. Rev. D 113, L091501 – Published 1 May, 2026

DOI: https://doi.org/10.1103/wrv9-t9vv

Abstract

Using $(2.712 \pm 0.014) \times 10^{9} ψ (3686)$ events collected with the BESIII detector at the BEPCII collider, we report an evidence of $Ξ^{0}$ transverse polarization with a significance of $4.4 σ$ , a precise measurement of the branching fraction and the ratios between the $S$ -wave and $D$ -wave contributions of $ψ (3686) \to Ξ^{0} {\bar{Ξ}}^{0}$ . The weak decay parameters ( $ϕ_{Ξ^{0} / {\bar{Ξ}}^{0}}$ , $α_{Ξ^{0} / {\bar{Ξ}}^{0}}$ ) and the angular distribution ( $α_{ψ}$ ) are also measured with higher precision compared to the previous measurements. Furthermore, two the $C P$ observables are also determined to be $A_{C P}^{Ξ^{0}} = - 0.014 \pm 0.030 \pm 0.010$ and $Δ ϕ_{C P}^{Ξ^{0}} = 0.000 \pm 0.028 \pm 0.003 rad$ , which are still consistent with $C P$ conservation at $1 σ$ level under the current statistics.

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Phys. Rev. D 113, L091501– Published 1 May, 2026

Vol. 113, Iss. 9 — 1 May 2026

Received 22 October 2025
Accepted 26 March 2026

DOI: https://doi.org/10.1103/wrv9-t9vv

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP³.

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Evidence of transverse polarization of the $Ξ^{0}$ hyperon in $ψ (3686) \to Ξ^{0} {\bar{Ξ}}^{0}$

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Evidence of transverse polarization of the Ξ0 hyperon in ψ(3686)→Ξ0Ξ¯0

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Evidence of transverse polarization of the $Ξ^{0}$ hyperon in $ψ (3686) \to Ξ^{0} {\bar{Ξ}}^{0}$