2003•arXiv (Cornell University)Open access
Observation of S=+1 Baryon Resonance in Photo-production from Neutron
Takayoshi Nakano, D. S. Ahn, J. K. Ahn, H. Akimune, Y. Asano, W. C. Chang, S. Daté, H. Ejiri, H. Fujimura, M. Fujiwara, K. Hicks, T. Hotta, K. Imai, Tomoko Ishikawa, T. Iwata, H. Kawai, Z. Y. Kim, K. Kino, H. Kohri, Naoya Kumagai, Shoji Makino, Takeshi Matsumura, N. Matsuoka, T. Mibe, K. Miwa, M. Miyabe, Y. Miyachi, Masato Morita, N. Muramatsu, M. Niiyama, M. Nomachi, Y. Ōhashi, T. Ooba, H. Ohkuma, D. S. Oshuev, C. Rangacharyulu, A. Sakaguchi, T. Sasaki, P. Shagin, Y. Shiino, H. Shimizu, Y. Sugaya, M. Sumihama, H. Toyokawa, A. Wakai, C. W. Wang, S. C. Wang, K. Yonehara, T. Yorita, Masaki Yoshimura, M. Yosoi, R. G. T. Zegers
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Abstract
The gamma n -> K+ K- n reaction on 12C has been studied by measuring both K+ and K- at forward angles. A sharp baryon resonance peak was observed at 1.54 +- 0.01 GeV with a width smaller than 25 MeV and a Gaussian significance of 4.6 sigma. The strangeness quantum number (S) of the baryon resonance is +1. It can be interpreted as a molecular meson-baryon resonance or alternatively as an exotic 5-quark state (uudd{s_bar}) that decays into a K+ and a neutron. The resonance is consistent with the lowest member of an anti-decuplet of baryons predicted by the chiral soliton model.