Chiral Approach to Weak Radiative Hyperon Decays and the $\Xi^0 --> \Lambda \gamma $ Asymmetry

TL;DR

This paper reanalyzes a chiral model for weak radiative hyperon decays, showing that classification choices significantly affect decay asymmetry predictions, especially for the $ ext{Xi}^0 o ext{Lambda} ext{gamma}$ decay.

Contribution

It demonstrates how the classification of $ ext{Lambda}(1405)$ impacts decay asymmetry predictions within the chiral model.

Findings

Reclassification of $ ext{Lambda}(1405)$ alters decay asymmetry predictions.

Large negative asymmetry for $ ext{Xi}^0 o ext{Lambda} ext{gamma}$ decay.

Contrasts with approaches violating Hara's theorem.

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 $\Lambda (1405)$ as an SU(3)-singlet. In particular, for the $\Xi ^0 \to \Lambda \gamma $ decay large negative asymmetry is obtained. This is contrasted with the Hara's-theorem-violating approaches where this asymmetry is large and positive.