1. ' ', a -meson Nuclear Bound State, Observed in He( ,λ ) Reactions
- Author
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Ajimura, S., Asano, H., Beer, G., Berucci, C., Bhang, H., Bragadireanu, M., Buehler, P., Busso, L., Cargnelli, M., Choi, S., Curceanu, C., Enomoto, S., Fujioka, H., Fujiwara, Y., Fukuda, T., Guaraldo, C., Hashimoto, T., Hayano, R.S., Hiraiwa, T., Iio, M., Iliescu, M., Inoue, K., Ishiguro, Y., Ishikawa, T., Ishimoto, S., Itahashi, K., Iwasaki, M., Kanno, K., Kato, K., Kato, Y., Kawasaki, S., Kienle, P., Kou, H., Ma, Y., Marton, J., Matsuda, Y., Mizoi, Y., Morra, O., Nagae, T., Noumi, H., Ohnishi, H., Okada, S., Outa, H., Piscicchia, K., Sada, Y., Sakaguchi, A., Sakuma, F., Sato, M., Scordo, A., Sekimoto, M., Shi, H., Shirotori, K., Sirghi, D., Sirghi, F., Suzuki, K., Suzuki, S., Suzuki, T., Tanida, K., Tatsuno, H., Tokuda, M., Tomono, D., Toyoda, A., Tsukada, K., Vazquez Doce, O., Widmann, E., Yamaga, T., Yamazaki, T., Zhang, Q., and Zmeskal, J.
- Abstract
We observed a distinct peak in the Λp invariant mass spectrum of He3(K−,Λp)n, well below mK+2mp, i.e., the mass threshold of the K− to be bound to two protons. By selecting a relatively large momentum-transfer region q=350∼650 MeV/c, one can kinematically separate the peak from the quasi-free process, K‾N→K‾N followed by the non-resonant absorption by the two spectator-nucleons K‾NN→ΛN. We found that the simplest fit to the observed peak gives us a Breit–Wigner pole position at BKpp=47±3(stat.)−6+3(sys.) MeV having a width ΓKpp=115±7(stat.)−20+10(sys.) MeV, and the S-wave Gaussian reaction form-factor parameter QKpp=381±14(stat.)−0+57(sys.) MeV/c, as a new form of the nuclear bound system with strangeness – “K−pp”.
- Published
- 2019