Exotics in the nuclear system with strangeness

“介子核”是指含有奇异夸克的反介子核，被认为具有诸如高密度态等奇异性质。为了揭示kaonic核的本质，我们从理论上用一些近似的方法研究了最基本的kaonic核“K^-pp”（由一个K^-介子和两个质子组成的系统）。结果发现，尽管K^介子的强烈吸引力使两个质子相互靠近，但两个核子之间的强烈斥力阻止了两个质子相互靠近。K^-pp中两个质子之间的距离被证实几乎等于正常原子核的距离。因此，我们认为K^-pp是一种正常密度的态，而不是高密度态。

“Kaonic nuclei” which mean nuclei with anti-kaon containing a strangeness quark are considered to have exotic properties such as highly dense state. In order to reveal the nature of kaonic nuclei, we have investigated the most essential kaonic nucleus “K^-pp” (a system consist of a K^-meson and two protons) theoretically with a little approximation. As a result, it is found that the very strong repulsion between two nucleons prevents two protons getting close to each other, in spite that the strong attraction from K^-meson makes them approach to each other. The distance between two protons in K^-pp is confirmed to be nearly equal to that for a normal nucleus. Therefore, we consider that the K^-pp is a state with the normal density, not highly dense.