학술논문
Search for $\eta'$ bound nuclei in the $^{12}{\rm C}(\gamma,p)$ reaction with simultaneous detection of decay products
Document Type
Working Paper
Author
Tomida, N.; Muramatsu, N.; Niiyama, M.; Ahn, J. K.; Chang, W. C.; Chen, J. Y.; Chu, M. L.; Daté, S.; Gogami, T.; Goto, H.; Hamano, H.; Hashimoto, T.; He, Q. H.; Hicks, K.; Hiraiwa, T.; Honda, Y.; Hotta, T.; Ikuno, H.; Inoue, Y.; Ishikawa, T.; Jaegle, I.; Jo, J. M.; Kasamatsu, Y.; Katsuragawa, H.; Kido, S.; Kon, Y.; Maruyama, T.; Masumoto, S.; Matsumura, Y.; Miyabe, M.; Mizutani, K.; Nagahiro, H.; Nakamura, T.; Nakano, T.; Nam, T.; Ngan, T. N. T.; Nozawa, Y.; Ohashi, Y.; Ohnishi, H.; Ohta, T.; Ozawa, K.; Rangacharyulu, C.; Ryu, S. Y.; Sada, Y.; Sasagawa, M.; Shibukawa, T.; Shimizu, H.; Shirai, R.; Shiraishi, K.; Strokovsky, E. A.; Sugaya, Y.; Sumihama, M.; Suzuki, S.; Tanaka, S.; Tokiyasu, A.; Tsuchikawa, Y.; Ueda, T.; Yamazaki, H.; Yamazaki, R.; Yanai, Y.; Yorita, T.; Yoshida, C.; Yosoi, M.
Source
Phys. Rev. Lett. 124, 202501 (2020)
Subject
Language
Abstract
We measured missing mass spectrum of the $^{12}{\rm C}(\gamma,p)$ reaction for the first time in coincidence with potential decay products from $\eta'$ bound nuclei. We tagged an ($\eta+p$) pair associated with the $\eta'N\to\eta N$ process in a nucleus. After applying kinematical selections to reduce backgrounds, no signal events were observed in the bound-state region. An upper limit of the signal cross section in the opening angle $\cos\theta^{\eta p}_{lab}<-0.9$ was obtained to be 2.2 nb/sr at the 90$\%$ confidence level. It is compared with theoretical cross sections, whose normalization ambiguity is suppressed by measuring a quasifree $\eta'$ production rate. Our results indicate a small branching fraction of the $\eta'N\to\eta N$ process and/or a shallow $\eta'$-nucleus potential.
Comment: 7 pages, 4 figures
Comment: 7 pages, 4 figures