Five-Quark Picture of Λ(1405) in Anisotropic Lattice QCD

Five-quark (5Q) picture of Λ(1405) is studiedusing quenched lattice QCD with an exotic 5Q operator of Nbar{K} type. To discreminate mere Nbar{K} and Σπ scattering states, Hybrid Boundary Condition (HBC), a flavor-dependent boundary condition, is imposed on the quark fields along spatial direction. 5Q mass m_{5Q}≃ 1.89 GeV is obtained after the chiral extrapolation to the physical quark mass region, which is too heavy to be identified with Λ(1405). Then, Λ(1405) seems neither a pure 3Q state nor a pure 5Q state, and therefore we present an interesting possibility that Λ(1405) is a mixed state of 3Q and 5Q states.