Hadronic few-body systems in chiral dynamics, -- Few-body systems in hadron physics --

TL;DR

This paper explores hadronic few-body systems, especially the $ar{K}N$ quasibound state $ ext{Lambda}(1405)$, extending the concept to kaonic few-body states and predicting systematic quasibound states near break-up thresholds.

Contribution

It extends the hadronic composite state framework to kaonic few-body systems, predicting new quasibound states based on chiral dynamics and coupled channel unitarity.

Findings

$ ext{Lambda}(1405)$ is described as a $ar{K}N$ quasibound state.

Predicted existence of $ar{K}NN$, $ar{K}KN$, and $ar{KKK}$ quasibound states.

Identification of $f_0(980)$ and $a_0(980)$ as $ar{K}K$ states.

Abstract

Hadronic composite states are introduced as few-body systems in hadron physics. The $\Lambda(1405)$ resonance is a good example of the hadronic few-body systems. It has turned out that $\Lambda(1405)$ can be described by hadronic dynamics in a modern technology which incorporates coupled channel unitarity framework and chiral dynamics. The idea of the hadronic $\bar KN$ composite state of $\Lambda(1405)$ is extended to kaonic few-body states. It is concluded that, due to the fact that $K$ and $N$ have similar interaction nature in s-wave $\bar K$ couplings, there are few-body quasibound states with kaons systematically just below the break-up thresholds, like $\bar KNN$, $\bar KKN$ and $\bar KKK$, as well as $\Lambda(1405)$ as a $\bar KN$ quasibound state and $f_{0}(980)$ and $a_{0}(980)$ as $\bar KK$.