标题： 我们是否在第二共振区有三个$S_{11}$共振？ 显示英文标题

标题： Do we have three $S_{11}$ resonances in the second resonance region?

摘要： 我们回顾了在一些最近的理论和现象学结果背景下，$S_{11}$ N$^*$ 谐振子的现状。 尽管夸克模型预测在约1.6 GeV处有两个这样的谐振子，但在该能量范围内有相当多的证据表明存在第三个$S_{11}$ 谐振子。 这表明在K介子产生阈值以下可能存在一个$K\Sigma$ 或$K\Lambda$ 的准束缚态。 我们表明，K介子产生实验，特别是$K^0$ 在核子上的光致产生，将对第三个$S_{11}$ 谐振子的存在非常敏感。 显示英文摘要

摘要： We review the status of the $S_{11}$ N$^*$ resonances in light of some recent theoretical and phenomenological results. Whereas the quark model predicts two such resonances around 1.6 GeV, there is considerable evidence for a third $S_{11}$ resonance in this energy range. This suggests that a $K\Sigma$ or $K\Lambda$ quasi-bound state may indeed exist below the kaon production threshold. We show that kaon production experiments, in particular $K^0$ photoproduction off nucleons, would be very sensitive to the existence of the third $S_{11}$ resonance.