AI 中文总结
利用耦合通道再散射框架分析BESIII关于\(ψ(3686)→K^-Λ\barΞ^+\)的数据，研究\(Ξ(1690)\)和\(Ξ(1820)\)共振性质，发现\(Ξ(1690)\)是虚拟态，\(Ξ(1820)\)有双极结构，为超子共振动力学产生提供新见解。
AI 中文摘要
我们通过在耦合通道再散射框架内分析BESIII关于\(ψ(3686)→K^-Λ\bar{\Xi}^+\)的最新数据，研究\(\Xi(1690)\)和\(\Xi(1820)\)共振的性质。计算包括\(\bar{K}\Lambda\)、\(\bar{K}\Sigma^{(*)}\)、\(\pi\Xi^{(*)}\)、\(\eta\Xi^{(*)}\)和\(K\Omega\)通道。直接拟合数据表明，\(\Xi(1690)\)最好描述为位于\(\bar{K}\Sigma\)阈值下方的虚拟态，这自然解释了在\(K^-\Lambda\)不变质量谱中观察到的非常尖锐的峰。相比之下，\(\Xi(1820)\)表现出主要源于\(K\Sigma^*\)和\(\pi\Xi^*\)通道耦合贡献的双极结构，显示出与著名的\(\Lambda(1405)\)相似的双极模式，并解释了BESIII测量的意外宽宽度。这些发现为超子共振的动力学产生提供了新见解，并突出了来自粲偶素衰变的高精度数据的重要性。
英文摘要
We investigate the nature of the $Ξ(1690)$ and $Ξ(1820)$ resonances by analyzing the recent BESIII data on $ψ(3686) \to K^-Λ\barΞ^+$ within a coupled-channel rescattering framework. The calculation includes the channels $\bar{K}Λ$, $\bar{K}Σ^{(*)}$, $πΞ^{(*)}$, $ηΞ^{(*)}$, and $KΩ$. A direct fit to the data reveals that the $Ξ(1690)$ is best described as a virtual state located right below the $\bar{K}Σ$ threshold, a feature that naturally explains its very sharp peak observed in the $K^-Λ$ invariant mass spectrum. In contrast, the $Ξ(1820)$ exhibits a two-pole structure originating mainly from the coupled contributions of the $KΣ^*$ and $πΞ^*$ channels, showing a two-pole pattern similar to that of the well-known $Λ(1405)$ and accounting for the unexpectedly broad width measured by BESIII. These findings provide new insights into the dynamical generation of hyperon resonances and highlight the importance of high-precision data from charmonium decays.
Comments13 pages, 6 figures
