Search for the double-charmonium state with η c J/ψ at Belle

• Published in: The journal of high energy physics Vol. 2023; no. 8; pp. 1 - 21
• Main Authors: The Belle collaboration, Y. B. Li, I. Adachi, S. Al Said, D. M. Asner, Sw. Banerjee, P. Behera, K. Belous, J. Bennett, M. Bessner, B. G. Cheon, D. Cinabro, J. Cochran, S. Das, Z. Doležal, D. Ferlewicz, B. G. Fulsom, P. Goldenzweig, E. Graziani, T. Gu, C. Hadjivasiliou, K. Hayasaka, D. Herrmann, W.-S. Hou, C.-L. Hsu, N. Ipsita, A. Ishikawa, R. Itoh, M. Iwasaki, W. W. Jacobs, Q. P. Ji, S. Jia, Y. Jin, J. Kahn, T. Kawasaki, C. Kiesling, D. Y. Kim, K.-H. Kim, Y.-K. Kim, K. Kinoshita, A. Korobov, S. Korpar, E. Kovalenko, P. Križan, P. Krokovny, T. Kuhr, R. Kumar, J. S. Lange, S. C. Lee, L. K. Li, Y. Li, J. Libby, M. Masuda, T. Matsuda, S. K. Maurya, F. Meier, M. Merola, F. Metzner, R. Mizuk, G. B. Mohanty, D. Narwal, M. Nayak, N. K. Nisar, H. Ono, G. Pakhlova, H. Park, J. Park, S.-H. Park, S. Patra, L. E. Piilonen, E. Prencipe, N. Rout, G. Russo, S. Sandilya, A. Sangal, L. Santelj, V. Savinov, G. Schnell, Y. Seino, W. Shan, M. Starič, M. Takizawa, F. Tenchini, R. Tiwary, M. Uchida, T. Uglov, Y. Unno, S. Uno, S. E. Vahsen, G. Varner, A. Vinokurova, E. Wang, S. Watanuki, O. Werbycka, B. D. Yabsley, W. Yan, S. B. Yang, J. Yelton, Z. P. Zhang, V. Zhukova
• Format: Journal Article
• Language: English
• Published: SpringerOpen 01.08.2023
• Subjects: e +-e − Experiments; Exotics; QCD; Spectroscopy
• ISSN: 1029-8479
• DOI: 10.1007/JHEP08(2023)121

Abstract We measure the cross section of e + e − → η c J/ψ at the Υ(nS)(n = 1–5) on-resonance and 10.52 GeV off-resonance energy points using the full data sample collected by the Belle detector with an integrated luminosity of 955 fb −1. We also search for double charmonium production in e + e − → η c J/ψ via initial state radiation near the η c J/ψ threshold. No evident signal of the double charmonium state is found, but evidence for the e + e − → η c J/ψ process is found with a statistical significance greater than 3.3σ near the η c J/ψ threshold. The average cross section near the threshold is measured and upper limits of cross sections are set for other regions.