HYPERON RADIATIVE DECAYS

Abstract

We review the experimental and theoretical status of weak radiative hyperon decays. Our discussion centers on a controversy over the validity of Hara’s theorem, which was originally expected to be respected by these decays. After presenting the hadron level theorem we describe experiments that have provided convincing evidence against its applicability to these decays. In the theoretical part we juxtapose the hadron level and quark level approaches and discuss the violation of Hara’s theorem in the latter. We review quark model phenomenology, which offers a promising description of experimental data. Measurements that should be made to settle the theoretical controversy are pinpointed. The importance of radiative hyperon decays in understanding the nonlocal composite nature of hadrons is stressed.