Open Access

Medina Ablikim, Mikhail N. Achasov, Patrik Adlarson, Samer Ahmed, Malte Albrecht, Antonio Amoroso, Qi An, Anita, Yu 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, Hao Cai, Xiao 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, W. Cheng, Gianluigi Cibinetto, Fabio Cossio, X. F. Cui, Hongliang Dai, J. P. Dai, Xinchen Dai, Alaa Dbeyssi, R. B. de Boer, Dmitri V. Dedovich, Ziyan Deng, Achim Denig, Igor Denysenko, Marco Giovanni Maria Destefanis, Francesca De Mori, Yanchun 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, Y. Fu, X. L. Gao, Y. Gao, Y. Gao, Y. G. Gao, Isabella Garzia, Evelina Gersabeck, A. Gilman, Klaus Götzen, 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, Frederick Allan 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, M. 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, 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, Lia Lavezzi, Hans Heinrich Leithoff, Max Lellmann, Thomas Lenz, C. Li, C. H. Li, Cheng Li, D. M. Li, F. Li, G. Li, Haibo Li, H. J. Li, J. L. Li, J. Q. Li, Ke Li, L. K. Li, Lei Li, P. L. Li, P. R. Li, S. Y. Li, Weidong Li, Weiguo Li, X. H. Li, Xing Long 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, L. Y. Liu, Q. Liu, S. B. Liu, T. Liu, X. Liu, Y. B. Liu, Zhen-An Liu, Z. Q. Liu, Y. F. Long, Xinchou Lou, 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. 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, Hajime Muramatsu, Simon Nakhoul, Yury Nefedov, Frank Nerling, Ivan Borisovich Nikolaev, Z. Ning, Shabana Nisar, Stephen L. Olsen, Qun Ouyang, Simone Pacetti, Y. Pan, Michael Papenbrock, A. Pathak, Piero 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, T. Y. Qi, S. Qian, W.-B. 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, Andrei V. Sarantsev, Mauro Savrié, Yasemin Schelhaas, Claudius Schnier, Karin Schönning, Wei Shan, Xinyu Shan, 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, Q. Q. Song, Y. X. Song, Stefano Sosio, Stefano Spataro, F. F. Sui, Gongxing Sun, J. F. Sun, L. Sun, S. S. Sun, T. Sun, W. Y. Sun, Y. J. Sun, Y. K. Sun, Y. Z. Sun, Z. T. Sun, Y. X. Tan, C. J. Tang, G. Y. Tang, J. Tang, Viktor Thoren, B. Tsednee, Ismail Uman, B. Wang, B. L. Wang, C. W. Wang, D. Y. Wang, H. P. Wang, K. Wang, L. L. Wang, M. Wang, M. Z. Wang, Meng 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, Z. Wang, Zongyuan Wang, Ziyi Wang, Zongyuan Wang, T. Weber, D. H. Wei, Peter Weidenkaff, Frederik Weidner, H. W. Wen, Shuopin Wen, D. J. White, Ulrich Wiedner, Guy 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, 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, W. Xu, Xinping Xu, L. Yan, L. Yan, W. B. Yan, W. C. 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, C. X. Yue, Alperen Yüncü, A. A. Zafar, Y. Zeng, B. X. Zhang, Guangyi Zhang, H. H. Zhang, Hongyu Zhang, J. L. Zhang, J. Q. Zhang, J. W. 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, 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 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, A. N. Zhu, Jianhui Zhu, K. Zhu, Kejun Zhu, S. H. Zhu, W. J. Zhu, X. L. Zhu, Y. C. Zhu, Zian Zhu, B. S. Zou, Jiaheng Zou

• We report a measurement of the observed cross sections of e+ e− → J/ψX based on 3.21 fb − 1 of data accumulated at energies from 3.645 to 3.891 GeV with the BESIII detector operated at the BEPCII collider. In analysis of the cross sections, we measured the decay branching fractions of B(ψ(3686) → J/ψX) = (64.4 ± 0.6 ± 1.6)% and B(ψ(3770) → J/ψX) = (0.5 ± 0.2 ± 0.1)% for the first time. The energy-dependent line shape of these cross sections cannot be well described by two Breit-Wigner (BW) amplitudes of the expected decays ψ (3686) → J/ψX and ψ(3770) → J/ψX. Instead, it can be better described with one more BW amplitude of the decay R(3760)→ J/ψX. Under this assumption, we extracted the R (3760) mass M R (3760 ) = 3766.2 ± 3.8 ± 0.4 MeV/c2, total width Γ tot R ( 3760 ) = 22.2 ± 5.9 ± 1.4 MeV, and product of leptonic width and decay branching fraction ΓeeR(3760) B[R(3760) → J/ψX] = (79.4 ± 85.5 ± 11.7) eV. The significance of the R(3760) is 5.3σ. The first uncertainties of these measured quantities are from fits to the cross sections and second systematic.