E2/M1 MIXING-RATIO OF DELTA-]N-GAMMA AND HYPERON RESONANCE RADIATIVE DECAY

We complete the leading contribution to the E2/M1 mixing ratio of the decay DELTA-->Ngamma in heavy baryon chiral perturbation theory. We find the mixing ratio to be 4% less than or similar to \delta(E2/M1)\ less than or similar to 11%, much larger than estimates based on the quark model and other hadronic models. We also compute the mixing ratio for the radiative decay of the hyperon resonances. The decays SIGMA*+ --> SIGMA+gamma and XI*- --> XI- gamma provide a particularly sensitive probe of deviations from heavy baryon spin-flavour SU(6).