Chiral Approach to Weak Radiative Hyperon Decays and the $Ξ^0 --> Λγ$ Asymmetry

Abstract

We reanalyse the recent version of the chiral model of weak radiative hyperon decays, proposed by Borasoy and Holstein. It is shown that predictions of the analysed model are significantly changed when one accepts the usual classification of $Λ(1405)$ as an SU(3)-singlet. In particular, for the $Ξ^0 \to Λγ$ decay large negative asymmetry is obtained. This is contrasted with the Hara's-theorem-violating approaches where this asymmetry is large and positive.