The radiative decay of the Λ(1405) and its two-pole structure

We evaluate theoretically the radiative decay widths into gamma Lambda and gamma Sigma(0) of the two poles' of the A(1405) found in chiral unitary theories and we find quite different results for each of the two poles. We show that, depending on which reaction is used to measure the A(1405) radiative decays, one gives more weight to one or the other pole, resulting in quite different shapes in the gamma Lambda(Sigma(0)) invariant-mass distributions. Our results for the high-energy pole agree with those of the empirical determination of the gamma Lambda and gamma Sigma(0) radiative widths (based on an isobar model fitting of the K-p atom data), which are sometimes referred to as experimental data. We have made a detailed study of the K(-)p -> pi(0)gamma Lambda(Sigma(0)) and pi(-)rho -> K-0 gamma Lambda(Sigma(0)) reactions and have shown that they, indeed, lead to different shapes for the -yA(ZO) invariant-mass distributions.