论文标题
$λ（1405）$共振作为真正的三夸克或分子状态
The $Λ(1405)$ resonance as a genuine three-quark or molecular state
论文作者
论文摘要
$λ（1405）$共振的形成的机制是在包括夸克 - 梅森和触点（四点）相互作用的手性夸克模型中研究的。在统一的耦合通道框架中计算出负值$ s $ s $ - 波散射幅度$ -1 $和1 $ $ \ frac12^ - $共振。我们表明，为了重现$ s_ {01} $部分波中的散射幅度，重要的是要包含相关的三夸克八位八分位省以及单元状态，而包含接触项的范围不是强制性的。 Laurent-Pietarinen扩展用于确定$ S $ -MATRIX杆。随着它们的发展作为提高相互作用强度的函数，由于$πς$和$ \ bar {k} n $ channels的自我能源有吸引力的自我能源，因此单线状态的质量大大减少；当它降至$ kn $阈值以下时，该州将获得一个主要的$ \ bar {k} n $组件，可以用分子状态识别。 KAON与细胞核之间的吸引力是通过$ \ bar {k}nλ^*$相互作用而不是通过梅森 - 尼克莱恩力产生的。
The mechanism for the formation of the $Λ(1405)$ resonance is studied in a chiral quark model that includes quark-meson as well as contact (four point) interactions. The negative-parity $S$-wave scattering amplitudes for strangeness $-1$ and $1$ are calculated within a unified coupled-channel framework that includes the $KN$, $\bar{K}N$, $πΣ$, $ηΛ$, $KΞ$, $πΛ$, and $ηΣ$ channels and possible genuine three-quark bare singlet and octet states corresponding to $\frac12^-$ resonances. We show that in order to reproduce the scattering amplitudes in the $S_{01}$ partial wave it is important to include the pertinent three-quark octet states as well as the singlet state, while the inclusion of the contact term is not mandatory. The Laurent-Pietarinen expansion is used to determine the $S$-matrix poles. Following their evolution as a function of increasing interaction strength, the mass of the singlet state is strongly reduced due to the attractive self-energy in the $πΣ$ and $\bar{K}N$ channels; when it drops below the $KN$ threshold, the state acquires a dominant $\bar{K}N$ component which can be identified with a molecular state. The attraction between the kaon and the nucleon is generated through the $\bar{K}NΛ^*$ interaction rather than by meson-nucleon forces.
