Search for deeply bound kaonic state

为了观察深度束缚的高子核态，我们在KEK-PS上进行了一系列实验(E471/E549/E570)。如果K介子与原子核之间的相互作用具有很强的吸引力，K介子就会吸引邻近的核子，形成高密度的核物质，形成深束缚的高介子核，当结合变大时，其主要衰变通道关闭，高能子核的宽度变窄。为此，我们测量了^4He(K-停止，N)反应的中子/质子能谱。在两个中子/质子谱中，我们没有观察到包含谱中的窄峰。从中子谱和质子谱都得到了窄的高子态形成速率的严格上限。我们曾经报道过在E471实验的质子谱中有一个很窄的峰--S0(3115)，这是由于专门的高能统计实验E549的实验结果中的实验伪影造成的。由于E549/E570数据的高统计特性，我们可以成功地测量超子(Λ或Σ)和核子(S)(n/p或d)的能量和角关联。特别是对Λ通道的独有测量，为研究相对宽广的高子核态打开了大门。我们现在正计划在J-PARC用^3He(飞行中的K-，n)反应对K-pp系统进行独家测量。

In order to observe deeply bound kaonic nuclear states, we carried out series of experiments (E471/E549/E570) at KEK-PS. If the interaction between kaon and nucleus is strongly attractive, K meson attracts neighboring nucleons and can form high density nuclear matter and can form deeply bound kaonic nuclei.When the binding becomes large, its major decay channel closes and the kaonic nuclei can have narrow widths. To this end, we measured neutron/proton spectra from ^4He(K-stopped, N) reactions. In both of neutron/proton spectra, we do not observe narrow peaks in the inclusive spectra. Tight upper limits for the formation rate of narrow kaonic states were obtained ftom both of neutron and proton spectra. We once reported a narrow peak -S0(3115)- in the proton spectrum in E471 experiment, it was found to be due to the experimental artifacts from the in results of the dedicated high-statistics experiment, E549.Thanks to the high statistics of E549/E570 data, we could successfully measure the energy and angular correlation of hyperon (Λ or Σ) and nucleon(s) (n/p or d). Especially, exclusive measurement of Λnd channel opened the door to investigate the gate to study the kaonic nuclear states with relatively broad widths. We are now planning to do exclusive measurement of K-pp system with ^3He(in-flight K-,n) reaction at J-PARC.