Observation of a Near-Threshold Structure in the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mi>K</mml:mi><mml:mo>+</mml:mo></mml:msup></mml:math> Recoil-Mass Spectra in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi>e</mml:mi></mml:mrow><mml:mrow><mml:mo>+</mml:mo></mml:mrow></mml:msup><mml:msup><mml:mrow><mml:mi>e</mml:mi></mml:mrow><mml:mrow><mml:mo>−</mml:mo></mml:mrow></mml:msup><mml:mo stretchy="false">→</mml:mo><mml:msup><mml:mrow><mml:mi>K</mml:mi></mml:mrow><mml:mrow><mml:mo>+</mml:mo></mml:mrow></mml:msup><mml:mo stretchy="false">(</mml:mo><mml:msubsup><mml:mrow><mml:mi>D</mml:mi></mml:mrow><mml:mrow><mml:mi>s</mml:mi></mml:mrow><mml:mrow><mml:mo>−</mml:mo></mml:mrow></mml:msubsup><mml:msup><mml:mrow><mml:mi>D</mml:mi></mml:mrow><mml:mrow><mml:mo>*</mml:mo><mml:mn>0</mml:mn></mml:mrow></mml:msup><mml:mo>+</mml:mo><mml:msubsup><mml:mrow><mml:mi>D</mml:mi></mml:mrow><mml:mrow><mml:mi>s</mml:mi></mml:mrow><mml:mrow><mml:mo>*</mml:mo><mml:mo>−</mml:mo></mml:mrow></mml:msubsup><mml:msup><mml:mrow><mml:mi>D</mml:mi></mml:mrow><mml:mrow><mml:mn>0</mml:mn></mml:mrow></mml:msup><mml:mo stretchy="false">)</mml:mo></mml:mrow></mml:math>
M. Ablikim(Institute of High Energy Physics), М. Н. Ачасов(Siberian Branch of the Russian Academy of Sciences), P. Adlarson(Uppsala University), S. Ahmed(Johannes Gutenberg University Mainz), M. Albrecht(Ruhr University Bochum), R. Aliberti(Johannes Gutenberg University Mainz), A. Amoroso(University of Turin), Q. An(University of Science and Technology of China), Anita(Indian Institute of Technology Madras), X. H. Bai(University of Jinan), Y. Bai(Southeast University), O. Bakina(Joint Institute for Nuclear Research), R. Baldini Ferroli(Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati), I. Balossino(Istituto Nazionale di Fisica Nucleare, Sezione di Ferrara), Y. Ban(Peking University), K. Begzsuren(Institute of Physics and Technology), N. Berger(Johannes Gutenberg University Mainz), M. Bertani(Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati), D. Bettoni(Istituto Nazionale di Fisica Nucleare, Sezione di Ferrara), F. Bianchi(University of Turin), J. Biernat(Uppsala University), J. Bloms(University of Münster), A. Bortone(University of Turin), I. Boyko(Joint Institute for Nuclear Research), R. A. Briere(Carnegie Mellon University), H. Cai(Wuhan University), X. Z. Cai(Institute of High Energy Physics), A. Calcaterra(Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati), G. F. Cao(Institute of High Energy Physics), N. Cao(Institute of High Energy Physics), S. A. Çetin(Istanbul Bilgi University), J. F. Chang(Institute of High Energy Physics), W. L. Chang(Institute of High Energy Physics), G. Chelkov(Joint Institute for Nuclear Research), D. Y. Chen(Central China Normal University), G. Chen(Institute of High Energy Physics), H. S. Chen(Institute of High Energy Physics), M. L. Chen(Institute of High Energy Physics), S. J. Chen(Nanjing University), X. R. Chen(Institute of Modern Physics), Y. B. Chen(Institute of High Energy Physics), Z. J. Chen(Hunan University), W. S. Cheng(University of Turin), G. Cibinetto(Istituto Nazionale di Fisica Nucleare, Sezione di Ferrara), F. Cossio(University of Turin), X. F. Cui(Nankai University), H. L. Dai(Institute of High Energy Physics), X. Dai(Institute of High Energy Physics), A. Dbeyssi(Johannes Gutenberg University Mainz), R. B. de Boer(Ruhr University Bochum), D. Dedovich(Joint Institute for Nuclear Research), Z. Y. Deng(Institute of High Energy Physics), A. Denig(Johannes Gutenberg University Mainz), I. Denysenko(Joint Institute for Nuclear Research), M. Destefanis(University of Turin), F. De Mori(University of Turin), Y. Ding(Liaoning University), C. Dong(Nankai University), J. Dong(Institute of High Energy Physics), L. Y. Dong(Institute of High Energy Physics), M. Y. Dong(Institute of High Energy Physics), X. Dong(Wuhan University), S. X. Du(Zhengzhou University), J. Fang(Institute of High Energy Physics), S. S. Fang(Institute of High Energy Physics), Y. Fang(Institute of High Energy Physics), R. Farinelli(Istituto Nazionale di Fisica Nucleare, Sezione di Ferrara), L. Fava(Università degli Studi del Piemonte Orientale “Amedeo Avogadro”), F. Feldbauer(Ruhr University Bochum), G. Felici(Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati), C. Q. Feng(University of Science and Technology of China), M. Fritsch(Ruhr University Bochum), C. D. Fu(Institute of High Energy Physics), Y. Fu(Institute of High Energy Physics), Y. Gao(University of Science and Technology of China), Y. Gao(University of Science and Technology of China), Y. Gao(University of Science and Technology of China), Y. Gao(University of Science and Technology of China), I. Garzia(University of Ferrara), E. Gersabeck(University of Manchester), A. Gilman(University of Minnesota), K. Goetzen(GSI Helmholtz Centre for Heavy Ion Research), Lu Gong(Liaoning University), W. X. Gong(Institute of High Energy Physics), W. Gradl(Johannes Gutenberg University Mainz), M. Greco(University of Turin), L. M. Gu(Nanjing University), M. H. Gu(Institute of High Energy Physics), S. Gu(Beihang University), Y. T. Gu(Guangxi University), C. Y. Guan(Institute of High Energy Physics), A. Q. Guo(Indiana University Bloomington), L. B. Guo(Nanjing Normal University), R. P. Guo(Shandong Normal University), Y. P. Guo(Johannes Gutenberg University Mainz), Y. P. Guo(Johannes Gutenberg University Mainz), A. Guskov(Joint Institute for Nuclear Research), T. T. Han(Shandong University), X. Q. Hao(Henan Normal University), F. A. Harris(University of Hawaiʻi at Mānoa), K. L. He(Institute of High Energy Physics), F. H. Heinsius(Ruhr University Bochum), C. H. Heinz(Johannes Gutenberg University Mainz), T. Held(Ruhr University Bochum), Y. K. Heng(Institute of High Energy Physics), C. Herold(Suranaree University of Technology), M. Himmelreich(GSI Helmholtz Centre for Heavy Ion Research), T. Holtmann(Ruhr University Bochum), Y. R. Hou(University of Chinese Academy of Sciences), Z. L. Hou(Institute of High Energy Physics), H. M. Hu(Institute of High Energy Physics), J. F. Hu(South China Normal University), T. Hu(Institute of High Energy Physics), Y. Hu(Institute of High Energy Physics), G. S. Huang(University of Science and Technology of China), L. Q. Huang(University of South China), X. T. Huang(Shandong University), Yin Huang(Institute of High Energy Physics), Z. Huang(Peking University), N. Huesken(University of Münster), T. Hussain(University of the Punjab), W. Ikegami Andersson(Uppsala University), W. Imoehl(Indiana University Bloomington), M. Irshad(University of Science and Technology of China), S. Jaeger(Ruhr University Bochum), S. Janchiv(Institute of Physics and Technology), Q. P. Ji(Institute of High Energy Physics), Q. P. Ji(Institute of High Energy Physics), X. B. Ji(Institute of High Energy Physics), X. L. Ji(Institute of High Energy Physics), H. B. Jiang(Shandong University), X. S. Jiang(Nankai University), X. Y. Jiang(Nankai University), Y. J. Jiang(University of Chinese Academy of Sciences), J. B. Jiao(Shandong University), Z. Jiao(Huangshan University), S. Jin(Nanjing University), Y. Jin(University of Jinan), T. Johansson(Uppsala University), N. Kalantar-Nayestanaki(University of Groningen), X. S. Kang(Liaoning University), R. Kappert(University of Groningen), M. Kavatsyuk(University of Groningen), B. C. Ke(Institute of High Energy Physics), I. K. Keshk(Ruhr University Bochum), A. Khoukaz(University of Münster), P. Kiese(Johannes Gutenberg University Mainz), R. Kiuchi(Institute of High Energy Physics), R. Kliemt(GSI Helmholtz Centre for Heavy Ion Research), L. Koch(Justus-Liebig-Universität Gießen), O. B. Kolcu(Istanbul Bilgi University), B. Kopf(Ruhr University Bochum), M. Kuemmel(Ruhr University Bochum), M. Kuessner(Ruhr University Bochum), A. Kupść(Uppsala University), M. G. Kurth(Institute of High Energy Physics), W. Kühn(Justus-Liebig-Universität Gießen), J. J. Lane(University of Manchester), J. S. Lange(Justus-Liebig-Universität Gießen), P. Larin(Johannes Gutenberg University Mainz), L. Lavezzi(University of Turin), Z. H. Lei(University of Science and Technology of China), H. Leithoff(Johannes Gutenberg University Mainz), M. Lellmann(Johannes Gutenberg University Mainz), T. Lenz(Johannes Gutenberg University Mainz), C. Li(University of Science and Technology of China), C. H. Li(University of Science and Technology of China), Cheng Li(University of Science and Technology of China), D. M. Li(Zhengzhou University), Fangchan Li(Institute of High Energy Physics), G. Li(Institute of High Energy Physics), H. Li(University of Science and Technology of China), H. Li(University of Science and Technology of China), H. B. Li(University of Science and Technology of China), H. J. Li(University of Science and Technology of China), J. L. Li(Shandong University), J. Q. Li(Shandong University), Ke Li(Institute of High Energy Physics), L. K. Li(Beijing Institute of Petrochemical Technology), Lei Li(Beijing Institute of Petrochemical Technology), P. L. Li(University of Science and Technology of China), P. R. Li(University of Science and Technology of China), Shaoqi Li(Tsinghua University), W. D. Li(Institute of High Energy Physics), W. G. Li(Institute of High Energy Physics), X. H. Li(University of Science and Technology of China), X. L. Li(University of Science and Technology of China), Z. Y. Li(Sun Yat-sen University), Hai‐Wei Liang(University of Science and Technology of China), Hai‐Wei Liang(University of Science and Technology of China), Y. F. Liang(Sichuan University), Y. T. Liang(Sichuan University), L. Z. Liao(Institute of High Energy Physics), J. Libby(Indian Institute of Technology Madras), C. X. Lin(Sun Yat-sen University), B. J. Liu(Institute of High Energy Physics), C. X. Liu(Institute of High Energy Physics), D. Liu(University of Science and Technology of China), F. H. Liu(Shanxi University), Fang Liu(Shanxi University), Feng Liu(Shanxi University), F. H. Liu(Guangxi University), H. M. Liu(Guangxi University), Huanhuan Liu(Guangxi University), Huihui Liu(Guangxi University), J. B. Liu(University of Science and Technology of China), J. Y. Liu(University of Science and Technology of China), K. Liu(Liaoning University), K. Y. Liu(Liaoning University), Ke Liu(Liaoning University), L. Liu(University of Science and Technology of China), M. H. Liu(Fudan University), Q. Liu(University of Chinese Academy of Sciences), S. B. Liu(University of Science and Technology of China), Shuai Liu(University of Science and Technology of China), T. Liu(Institute of High Energy Physics), W. M. Liu(University of Science and Technology of China), X. Liu(Lanzhou University), Yu Liu(Nankai University), Y. B. Liu(Nankai University), Z. A. Liu(Shandong University), Z. Q. Liu(Shandong University), X. C. Lou(Institute of High Energy Physics), F. X. Lu(Henan Normal University), H. J. Lü(Huangshan University), J. D. Lu(Institute of High Energy Physics), J. G. Lu(Institute of High Energy Physics), X. L. Lu(Institute of High Energy Physics), Y. Lu(Institute of High Energy Physics), Y. P. Lu(Institute of High Energy Physics), C. L. Luo(Nanjing Normal University), M. X. Luo(Zhejiang University), P. W. Luo(Sun Yat-sen University), T. Luo(Fudan University), X. L. Luo(Institute of High Energy Physics), S. Lusso(University of Turin), X. R. Lyu(University of Chinese Academy of Sciences), F. C.(Liaoning University), H. L.(Institute of High Energy Physics), L. L.(Shandong University), M. Maggiora(Institute of High Energy Physics), Q. M.(Institute of High Energy Physics), R. Q.(Institute of High Energy Physics), R. T.(University of Chinese Academy of Sciences), X. N.(Nankai University), Xinxin Ma(Institute of High Energy Physics), X. Y.(Institute of High Energy Physics), F. E. Maas(Johannes Gutenberg University Mainz), M. Maggiora(University of Turin), S. Maldaner(Johannes Gutenberg University Mainz), S. Malde(University of Oxford), Q. A. Malik(University of the Punjab), A. Mangoni(Istituto Nazionale di Fisica Nucleare, Sezione di Perugia), Y. J. Mao(Peking University), Z. P. Mao(Institute of High Energy Physics), S. Marcello(University of Turin), Z. X. Meng(University of Jinan), J. G. Messchendorp(University of Groningen), G. Mezzadri(Istituto Nazionale di Fisica Nucleare, Sezione di Ferrara), T. J. Min(Nanjing University), R. E. Mitchell(Indiana University Bloomington), X. H. Mo(Institute of High Energy Physics), Y. J. Mo(Central China Normal University), N. Yu. Muchnoi(Siberian Branch of the Russian Academy of Sciences), H. Muramatsu(University of Minnesota), S. Nakhoul(GSI Helmholtz Centre for Heavy Ion Research), Y. Nefedov(Joint Institute for Nuclear Research), F. Nerling(GSI Helmholtz Centre for Heavy Ion Research), I. B. Nikolaev(Siberian Branch of the Russian Academy of Sciences), Z. Ning(Institute of High Energy Physics), S. Nisar(COMSATS University Islamabad), S. L. Olsen(University of Chinese Academy of Sciences), Q. Ouyang(Institute of High Energy Physics), S. Pacetti(University of Perugia), X. Pan(Fudan University), Y. Pan(University of Manchester), A. Pathak(Institute of High Energy Physics), P. Patteri(Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati), M. Pelizaeus(Ruhr University Bochum), H. P. Peng(University of Science and Technology of China), Κ. Peters(GSI Helmholtz Centre for Heavy Ion Research), J. Pettersson(Uppsala University), J. L. Ping(Nanjing Normal University), R. G. Ping(Institute of High Energy Physics), A. Pitka(Ruhr University Bochum), R. Poling(University of Minnesota), V. Prasad(University of Science and Technology of China), H. R. Qi(University of Science and Technology of China), H. R. Qi(University of Science and Technology of China), K. H. Qi(Institute of Modern Physics), M. Qi(Nanjing University), T. Y. Qi(Fudan University), T. Y. Qi(Fudan University), S. Qian(Institute of High Energy Physics), W. B. Qian(University of Chinese Academy of Sciences), Z. Qian(Sun Yat-sen University), C. F. Qiao(University of Chinese Academy of Sciences), L. Q. Qin(Guangxi Normal University), X. S. Qin(Shandong University), H. R. Qi(Institute of High Energy Physics), J. F. Qiu(Institute of High Energy Physics), S. Q. Qu(Nankai University), K. H. Rashid(University of the Punjab), K. Ravindran(Indian Institute of Technology Madras), C. F. Redmer(Johannes Gutenberg University Mainz), A. Rivetti(University of Turin), V. Rodin(University of Groningen), M. Rolo(University of Turin), G. Rong(Institute of High Energy Physics), Ch. Rosner(Johannes Gutenberg University Mainz), M. Rump(University of Münster), H. S. Sang(University of Science and Technology of China), A. Sarantsev(Joint Institute for Nuclear Research), Y. Schelhaas(Johannes Gutenberg University Mainz), C. Schnier(Ruhr University Bochum), K. Schoenning(Uppsala University), M. Scodeggio(Istituto Nazionale di Fisica Nucleare, Sezione di Ferrara), D. C. Shan(Soochow University), W. Shan(Hunan Normal University), X. Y. Shan(University of Science and Technology of China), M. Shao(University of Science and Technology of China), C. P. Shen(Fudan University), P. X. Shen(Nankai University), X. Y. Shen(Institute of High Energy Physics), B. A. Shi(University of Chinese Academy of Sciences), H. C. Shi(University of Science and Technology of China), R. S. Shi(Institute of High Energy Physics), X. Shi(University of Science and Technology of China), X. Shi(University of Science and Technology of China), W. M. Song(Jilin University), Y. X. Song(Peking University), S. Sosio(University of Turin), S. Spataro(University of Turin), K. X. Su(Wuhan University), F. F. Sui(Shandong University), G. X. Sun(Institute of High Energy Physics), H. K. Sun(Institute of High Energy Physics), J. F. Sun(Henan Normal University), L. Sun(Wuhan University), S. S. Sun(Institute of High Energy Physics), T. Sun(Institute of High Energy Physics), W. Y. Sun(Nanjing Normal University), X. H. Sun(Hunan University), Y. J. Sun(University of Science and Technology of China), Yi Sun(University of Science and Technology of China), Y. Z. Sun(University of Science and Technology of China), Z. T. Sun(Institute of High Energy Physics), Y. H. Tan(University of Science and Technology of China), Y. X. Tan(University of Science and Technology of China), C. J. Tang(Sichuan University), G. Y. Tang(Institute of High Energy Physics), Jiahui Tang(Sun Yat-sen University), J. X. Teng(University of Science and Technology of China), V. Thoren(Uppsala University), I. Uman(Near East University), C. W. Wang(Nanjing University), D. Y. Wang(Peking University), H. J. Wang(Institute of High Energy Physics), H. P. Wang(Institute of High Energy Physics), K. Wang(Institute of High Energy Physics), L. L. Wang(Institute of High Energy Physics), M. Wang(Shandong University), M. Z. Wang(Shandong University), Meng Wang(Shandong University), W. H. Wang(University of Science and Technology of China), W. P. Wang(University of Science and Technology of China), X. Wang(Peking University), X. F. Wang(Peking University), X. L. Wang(Peking University), Y. Wang(University of Science and Technology of China), Y. Q. Wang(University of Science and Technology of China), Y. D. Wang(University of Science and Technology of China), Y. F. Wang(University of Science and Technology of China), Y. Q. Wang(University of Science and Technology of China), Z. Wang(Institute of High Energy Physics), Z. Y. Wang(Institute of High Energy Physics), Ziyi Wang(Institute of High Energy Physics), Zongyuan Wang(Institute of High Energy Physics), D. H. Wei(Guangxi Normal University), P. Weidenkaff(Johannes Gutenberg University Mainz), F. Weidner(University of Münster), S. P. Wen(Institute of High Energy Physics), D. J. White(University of Manchester), U. Wiedner(Ruhr University Bochum), G. Wilkinson(University of Oxford), M. Wolke(Uppsala University), L. Wollenberg(Ruhr University Bochum), J. F. Wu(Institute of High Energy Physics), L. H. Wu(Institute of High Energy Physics), L. J. Wu(Institute of High Energy Physics), X. Wu(Fudan University), Z. Wu(Institute of High Energy Physics), L. Xia(University of Science and Technology of China), H. Xiao(Fudan University), S. Y. Xiao(Institute of High Energy Physics), Y. J. Xiao(Institute of High Energy Physics), Z. J. Xiao(Nanjing Normal University), X. H. Xie(Peking University), Y. Xie(Central China Normal University), Y. H. Xie(Central China Normal University), T. Y. Xing(Institute of High Energy Physics), G. F. Xu(Institute of High Energy Physics), J. Xu(Nanjing University), Q. Xu(Hangzhou Normal University), W. Xu(Institute of High Energy Physics), X. P. Xu(Soochow University), Y. C. Xu(University of Chinese Academy of Sciences), F. Yan(Fudan University), L. Yan(Fudan University), L. Yan(Fudan University), W. B. Yan(University of Science and Technology of China), W. C. Yan(University of Science and Technology of China), Yan Xu(Soochow University), H. J. Yang(Shanghai Jiao Tong University), H. X. Yang(Shanghai Jiao Tong University), Lei Yang(Shanxi Normal University), R. X. Yang(University of Science and Technology of China), S. L. Yang(Institute of High Energy Physics), S. L. Yang(Institute of High Energy Physics), Y. H. Yang(Guangxi Normal University), Y. Yang(Guangxi Normal University), Yifan Yang(Guangxi Normal University), Zhi Yang(Institute of Modern Physics), M. Ye(Institute of High Energy Physics), M. H. Ye(Institute of High Energy Physics), J. H. Yin(Institute of High Energy Physics), Z. Y. You(Sun Yat-sen University), B. X. Yu(Institute of High Energy Physics), C. X. Yu(Nankai University), Geum Bong Yu(Institute of High Energy Physics), J. S. Yu(Hunan University), Tao Yu(University of South China), C. Z. Yuan(Institute of High Energy Physics), L. Yuan(Beihang University), W. L. Yuan(University of Turin), X. Q. Yuan(Peking University), Ying Yuan(Institute of High Energy Physics), Z. Y. Yuan(Sun Yat-sen University), C. X. Yue(Liaoning Normal University), A. Yuncu(Near East University), A. A. Zafar(University of the Punjab), Y. Zeng(Hunan University), B. X. Zhang(Institute of High Energy Physics), Guangyi Zhang(Henan Normal University), H. Zhang(University of Science and Technology of China), H. H. Zhang(University of Science and Technology of China), H. Y. Zhang(University of Science and Technology of China), Junwei Zhang(Xinyang Normal University), J. L. Zhang(Xinyang Normal University), J. Q. Zhang(Xinyang Normal University), J. W. Zhang(Xinyang Normal University), J. Y. Zhang(Xinyang Normal University), J. Z. Zhang(Xinyang Normal University), Jianyu Zhang(Xinyang Normal University), Jiawei Zhang(Xinyang Normal University), Lei Zhang(Nanjing University), S. Zhang(Sun Yat-sen University), S. F. Zhang(Sun Yat-sen University), Shulei Zhang(Sun Yat-sen University), X. D. Zhang(North China Electric Power University), X. Y. Zhang(North China Electric Power University), Y. Zhang(University of Science and Technology of China), Y. H. Zhang(University of Science and Technology of China), Y. T. Zhang(University of Science and Technology of China), Yan Zhang(University of Science and Technology of China), Yao Zhang(University of Science and Technology of China), Yi Zhang(University of Science and Technology of China), Z. H. Zhang(Wuhan University), Z. Y. Zhang(Wuhan University), G. Zhao(Institute of High Energy Physics), J. Zhao(Liaoning Normal University), J. Y. Zhao(Liaoning Normal University), J. Z. Zhao(Liaoning Normal University), Lei Zhao(University of Science and Technology of China), Ling Zhao(University of Science and Technology of China), M. G. Zhao(Nankai University), Q. Zhao(Institute of High Energy Physics), S. J. Zhao(Zhengzhou University), Y. Zhao(Institute of Modern Physics), Y. X. Zhao(Institute of Modern Physics), Z. Zhao(University of Science and Technology of China), A. Zhemchugov(Joint Institute for Nuclear Research), B. Zheng(University of South China), Jingyi Zheng(Institute of High Energy Physics), Y. Zheng(Peking University), Y. Zheng(Peking University), B. Zhong(Nanjing Normal University), C. Zhong(University of South China), L. P. Zhou(Institute of High Energy Physics), Q. Zhou(Institute of High Energy Physics), X. R. Zhou(University of Science and Technology of China), X. K. Zhou(University of Science and Technology of China), X. R. Zhou(University of Science and Technology of China), A. N. Zhu(Institute of High Energy Physics), J. Zhu(Nankai University), K. J. Zhu(Institute of High Energy Physics), K. J. Zhu(Institute of High Energy Physics), S. H. Zhu(University of Science and Technology Liaoning), T. J. Zhu(Xinyang Normal University), W. J. Zhu(Nankai University), Xiaoyu Zhu(Tsinghua University), Y. C. Zhu(University of Science and Technology of China), Z. A. Zhu(Institute of High Energy Physics), B. S. Zou(Institute of High Energy Physics), J. H. Zou(Institute of High Energy Physics)
Cited by 186Open Access
Abstract
We report a study of the processes of e^{+}e^{-}→K^{+}D_{s}^{-}D^{*0} and K^{+}D_{s}^{*-}D^{0} based on e^{+}e^{-} annihilation samples collected with the BESIII detector operating at BEPCII at five center-of-mass energies ranging from 4.628 to 4.698 GeV with a total integrated luminosity of 3.7 fb^{-1}. An excess of events over the known contributions of the conventional charmed mesons is observed near the D_{s}^{-}D^{*0} and D_{s}^{*-}D^{0} mass thresholds in the K^{+} recoil-mass spectrum for events collected at sqrt[s]=4.681 GeV. The structure matches a mass-dependent-width Breit-Wigner line shape, whose pole mass and width are determined as (3982.5_{-2.6}^{+1.8}±2.1) MeV/c^{2} and (12.8_{-4.4}^{+5.3}±3.0) MeV, respectively. The first uncertainties are statistical and the second are systematic. The significance of the resonance hypothesis is estimated to be 5.3 σ over the contributions only from the conventional charmed mesons. This is the first candidate for a charged hidden-charm tetraquark with strangeness, decaying into D_{s}^{-}D^{*0} and D_{s}^{*-}D^{0}. However, the properties of the excess need further exploration with more statistics.
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