Search for a kaonic nuclear state via ${}^4$He$(K^{-},N)$

Abstract

Very recently, we have performed a couple of experiments, {\it{KEK PS-E549/E570}}, for the detailed study of the strange tribaryon $S^0(3115)$ obtained in {\it{KEK PS-E471}}. These experiments were performed to accumulate much higher statistics with improved experimental apparatusespecially for the better proton spectroscopy of the ${}^4$He({\it{stopped K}}${}^{-}$, {\it{N}}) reaction. In contrast to the previous proton spectrum, no narrow ($\sim$ 20 MeV) peak structure was found either in the inclusive ${}^4$He({\it{stopped K}}${}^{-}$, {\it{p}}) or in the semi-inclusive ${}^4$He({\it{stopped K}}${}^{-}$, {\it{p}}$X^{\pm }$) reaction channel, which is equivalent to the previous $E471$ event trigger condition. Detailed analysis of the present data and simulation shows that the peak, corresponding to $S^0(3115)$, has been an experimental artifact. Present analysis does not exclude the possible existence of a much wider structure. To be sensitive to such structure and for better understanding of the non-mesonic $K^{-}$ absorption reaction channel, detailed analysis of the data is in progress.

6 pages, 8 figures, conference HYP07 at Maintz