Radiative Hyperon Processes

Weak as well as pure electromagnetic radiative decays of hyperons are discussed. The radiative decays of excited hyperon states can provide information on the quark wave functions inside the hyperons. The weak (strangeness-changing) decays represent the last low-q2 frontier of weak-interaction physics. The theoretical motivation of these studies is reviewed, as well as the existing experiments. Special emphasis is placed on recent experiments at the Brookhaven AGS and at Fermilab. Radiative K− at rest on the deuteron is also discussed, and new results from Brookhaven are presented.