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

Hadronic composite states are introduced as few-body systems in hadron physics. The $\mathrm{\Lambda }(1405)$ resonance is a good example of the hadronic few-body systems. It has turned out that $\mathrm{\Lambda }(1405)$ 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 $\mathrm{\Lambda }(1405)$ 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 $\bar{K}NN$, $\bar KKN$and$\bar KKK$,aswellas$\Lambda(1405)$asa$\bar KN$ quasibound state and $f_0(980)$ and $a_0(980)$ as $\bar{K}K$.