Experimental Study of $\Lambda$(1405) by a Virtual Meson-Baryon Scattering

It is a long standing problem if $\Lambda$(1405) is a 3-quark state or a kaon nucleon bound state. Recent theoretical studies based on chiral unitary model claimed that $\Lambda$(1405) may consist of two components in a coupled-channel $\bar{K}N-\pi\Sigma$ system. Namely, poles coupled to $\bar{K} N$ and $\pi\Sigma$ are suggested at different positions. If it is true, decomposition of the two components are desired in the $\Lambda$(1405) spectrum. Since the $\Lambda(1405)$ state sits below $\bar{K}N$ threshold, it is of essentially importance to investigate a $\bar{K}N$ scattering process in a virtual state. The ($K^-$,n) reaction on deuteron is promissing to enhance a virtual $\bar{K}N$ reaction to produce $\Lambda$(1405). The experimetal study of $\Lambda$(1405) via the reaction has been proposed at J-PARC.