Hypercharge exchange reactions and hyperon resonance production

A review is presented of recent high statistics results on hypercharge exchange processes. Intermediate energy data on helicity non-flip dominated processes ( Sigma production) and on helicity-flip processes ( Sigma * production) reveal complicated and strongly energy-dependent systematics for exchange degeneracy breaking. Preliminary data at 70 GeV/c show evidence of the expected effects of high-lying J-plane singularities at mod t mod >or approximately=0.5. No existing model, or simple modification thereof, can describe the major features of the new data. (12 refs).