Single-pole nature of the detectable Lambda(1405)

Abstract

We have investigated the single-pole nature of the detectable Λ(1405) in detail, by employing a chiral model having double poles of a KN¯ -πΣ coupled-channel T-matrix. The effects of the first pole and the second pole on the observed πΣ mass spectrum in the Λ(1405) region have been analyzed almost separately. It is concluded that the first pole is responsible for both peak structures seen in the TπΣ←KN ¯ (T21) and TπΣ←πΣ(T22) invariant-mass spectra, and, due to an energy-dependent chiral interaction, the second pole provides continuum amplitudes affecting the shape of the peak structures of the first pole in the experimentally observable spectrum of Λ(1405).