Observation of a KNN bound state in the 3He(K, Λp)n reaction

T. Yamaga, S. Ajimura, H. Asano, G. Beer, H. Bhang, M. Bragadireanu, P. Buehler, L. Busso, M. Cargnelli, S. Choi, C. Curceanu, S. Enomoto, H. Fujioka, Y. Fujiwara, T. Fukuda, C. Guaraldo, T. Hashimoto, R. S. Hayano, T. Hiraiwa, M. IioM. Iliescu, K. Inoue, Y. Ishiguro, T. Ishikawa, S. Ishimoto, K. Itahashi, M. Iwai, M. Iwasaki, K. Kanno, K. Kato, Y. Kato, S. Kawasaki, P. Kienle, H. Kou, Y. Ma, J. Marton, Y. Matsuda, Y. Mizoi, O. Morra, T. Nagae, H. Noumi, H. Ohnishi, S. Okada, H. Outa, K. Piscicchia, Y. Sada, A. Sakaguchi, F. Sakuma, M. Sato, A. Scordo, M. Sekimoto, H. Shi, K. Shirotori, D. Sirghi, F. Sirghi, S. Suzuki, T. Suzuki, K. Tanida, H. Tatsuno, M. Tokuda, D. Tomono, A. Toyoda, K. Tsukada, O. Vazquez Doce, E. Widmann, T. Yamazaki, H. Yim, Q. Zhang, J. Zmeskal

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We have performed an exclusive measurement of the K + 3He → Λpn reaction at an incident kaon momentum of 1 GeV/c. In the Λp invariant mass spectrum, a clear peak was observed below the mass threshold of K¯ +N +N, as a signal of the kaonic nuclear bound state, KNN. The binding energy, decay width, and S-wave Gaussian reaction form-factor of this state were observed to be BK = 42 ± 3(stat.)+3−4(syst.) MeV, ΓK = 100 ± 7(stat.)+19−9 (syst.) MeV, and QK = 383 ± 11(stat.)+4−1(syst.) MeV/c, respectively. The total production cross-section of KNN, determined by its Λp decay mode, was σKtot · BRΛp = 9.3 ± 0.8(stat.)+1.4−1.0(syst.) µb. We estimated the branching ratio of the KNN state to the Λp and Σ0p decay modes as BRΛp/BRΣ0p ∼ 1.7, by assuming that the physical processes leading to the ΣNN final states are analogous to those of Λpn.

Original languageEnglish
JournalUnknown Journal
Publication statusPublished - 2020 Jun 23

ASJC Scopus subject areas

  • General

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