Within an extended chiral constituent quark model, three- and five-quark
structure of the S01​ resonance Λ(1405) is investigated. Helicity
amplitudes for the electromagnetic decays (Λ(1405)→Λ(1116)γ, Σ(1194)γ), and transition amplitudes for
strong decays (Λ(1405)→Σ(1194)π, K−p) are drived, as
well as the relevant decay widths. The experimental value for the strong decay
width, ΓΛ(1405)→(Σπ)∘​=50±2 MeV, is well
reproduced with about 50% of five-quark admixture in the Λ(1405).
Important effects due to the configuration mixings among
Λ12​PA​, Λ82​PM​ and Λ84​PM​ are
found. In addition, transitions between the three- and five-quark components in
the baryons turn out to be significant in both radiative and strong decays of
the Λ(1405) resonance.Comment: typos and numerical mistakes corrected, to appear in Phys. Rev.