Construction of a local K̄ N-π Σ-π Λ potential and composition of the Λ(1405) CONSTRUCTION of A LOCAL K̄ N-π Σ - . KENTA MIYAHARA, TETSUO HYODO, and WOLFRAM WEISE

A K̄N-πΣ-πΛ coupled-channel potential is constructed on the basis of chiral SU(3) dynamics. Several matching conditions are introduced to formulate an equivalent local potential that reproduces the coupled-channel scattering amplitudes resulting from chiral SU(3)L×SU(3)R meson-baryon effective field theory. In contrast to a previously constructed effective single-channel K̄N potential, the explicit treatment of the πΣ channel yields a natural description of the low-mass pole as part of the two-pole structure of the Λ(1405) resonance. The energy dependence of the potential can now be parametrized with a minimum of polynomial orders. To study the properties of the Λ(1405) as a quantum-mechanical quasibound state, we derive the normalization condition of its wave function generated by the energy-dependent coupled-channel potential, using the Feshbach projection method. This framework provides an improved understanding of this system from the viewpoint of the compositeness of hadrons. With the properly normalized wave function, we demonstrate and confirm that the high-mass pole of the Λ(1405) is dominated by the K̄N component.