Indication of a strange tribaryon S^+ from the ^4He(stopped K^-,n) reaction

Iwasaki, M.; Suzuki, T.; Bhang, H.; Franklin, G.; Gomikawa, K.; Hayano, R. S.; Hayashi, T.; Ishikawa, K.; Ishimoto, S.; Itahashi, K.; Katayama, T.; Kondo, Y.; Matsuda, Y.; Nakamura, T.; Okada, S.; Outa, H.; Quinn, B.; Sato, M.; Shindo, M.; So, H.; Sugimoto, T.; Strasser, P.; Suzuki, K.; Suzuki, S.; Tomono, D.; Vinodkumar, A. M.; Widmann, E.; Yamazaki, T.; Yoneyama, T.

Indication of a strange tribaryon S^+ from the ^4He(stopped K^-,n) reaction

Authors

Description

We measured the neutron time-of-flight spectrum in the ^4He(stopped K^-, n) reaction by stopping negative kaons in a superfluid helium target. A clear enhancement was observed in the neutron spectrum, which indicates the formation of a strange tribaryon of charge +1 with a mass and width of M = 3141 +/- 3 (stat.) +4/-1 (sys.) MeV/c^2 and G < 23 MeV/c^2. This state, denoted as S^+(3140), is about 25 MeV/c^2 higher than the previously observed S^0(3115) T=1.
13 pages, 7 figures, updated because of new reslut found in PLB597(2004)263