Five-quark picture of Lambda(1405) in anisotropic lattice QCD

Understand

Five-quark (5Q) picture of Lambda(1405) is studied using quenched lattice QCD with an exotic 5Q operator of N\bar{K} type.

• To discreminate mere N\bar{K} and \Sigma\pi scattering states, Hybrid Boundary Condition (HBC), a flavor-dependent boundary condition, is imposed on the quark fields along spatial direction.
• 5Q mass m_{5Q}\simeq 1.89 GeV is obtained after the chiral extrapolation to the physical quark mass region, which is too heavy to be identified with Lambda(1405).
• Then, Lambda(1405) seems neither a pure 3Q state nor a pure 5Q state, and therefore we present an interesting possibility that Lambda(1405) is a mixed state of 3Q and 5Q states.