Λ (1405) photoproduction at SPring-8/LEPS

The nature of Λ(1405) hyperon is still mystery for the distinction between an unstable K̄N bound state and L = 1 SU(3 -singlet three quark state coupled with the S-wave K̄N channels. Recent theoretical works predict its lineshape to be different in terms of different charge combinations of the π∑ decay channels in the context of chiral dynamics plus final-state interaction. We have measured the lineshape of Λ(1405) in charged π∑ channels through p(γ, K⁺π)∑ reaction at 1.5-2.4 GeV. The observed lineshapes in π^-∑⁺ and π⁺∑^- channels are different, which implies that the Λ(1405) could be interpreted as a bound-state of meson-baryon states.