Hyperon decays and QCD

In an experiment in the CERN Super Proton Synchrotron (SPS) charged hyperon beam, 2400 Omega /sup -/ decays have been collected. The analysis of the Omega /sup -/ sample has given an accurate measurement of the Omega /sup -/ lifetime ( tau ( Omega /sup -/)=(0.822+or-0.028) *10/sup -10/ s) and the first determination of the Omega /sup -/ decay branching ratios. In particular the measured ratio Gamma ( Omega /sup -/ to Xi /sup 0/ pi /sup -/)/ Gamma ( Omega /sup -/ to Xi /sup -/ pi /sup 0/) is 2.94+or-0.35, while a pure Delta I=1/2 amplitude would have given 2.03. A ratio of about 3 between those two decay modes had in fact been predicted by Finjord using the QCD framework. The author discusses briefly what QCD has to say about hyperon decays, then describes the Omega /sup -/ experiment and the analysis results. (8 refs).