Regular Article - Hadron Physics
The radiative decay of the Λ(1405) and its two-pole structure
Departamento de Fısica Teórica and IFIC, Centro Mixto, Institutos de Investigación de Paterna, Universidad de Valencia-CSIC, Valencia, Spain
Accepted: 24 April 2007
Published online: 18 May 2007
We evaluate theoretically the radiative decay widths into γΛ and γΣ 0 of the two poles of the Λ(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 Λ(1405) radiative decays, one gives more weight to one or the other pole, resulting in quite different shapes in the γΛ(Σ 0) invariant-mass distributions. Our results for the high-energy pole agree with those of the empirical determination of the γΛ and γΣ 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→π 0 γΛ(Σ 0) and π - p→K 0 γΛ(Σ 0) reactions and have shown that they, indeed, lead to different shapes for the γΛ(Σ 0) invariant-mass distributions.
PACS: 13.40.Hq Electromagnetic decays – / 14.20.Jn Hyperons – / 13.75.-n Hadron-induced low- and intermediate-energy reactions and scattering (energy ≤10GeV) – / 25.20.Lj Photoproduction reactions –
© Società Italiana di Fisica and Springer-Verlag, 2007