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

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 $\bar{K}N$ 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 $\bar{K}NN$, $\bar{K}KN$ and $\bar{K}KK$, as well as $\Lambda (1405)$ as a $\bar{K}N$ quasibound state and $f_0(980)$ and $a_0(980)$ as $\bar{K}K$.

Comments: 8 pages, 2 figures, contribution to 20th International IUPAP Conference on Few-Body Problems in Physics (FB20), 20-25 August 2011, Fukuoka, Japan