Measurement of Ξ−→Λπ− and Ω−→ΛK− Decay Parameters

Based on 144 million polarized Ξ−→Λπ−, Λ→pπ− and 5.5 million unpolarized Ω−→ΛK−, Λ→pπ− decays, the HyperCP collaboration at Fermilab has measured the decay parameters βΞ−, γΞ−, and αΩ−. Our results indicate that βΞ− and αΩ− are small, but nonzero. Implications of the βΞ− measurement on the Λπ− phase-shift difference will be discussed. The nonzero value of αΩ− is the first unambiguous evidence of parity violation in Ω− decays. A preliminary measurement of αΩ¯+ will also be presented, based on 1.9 million Ω¯+→Λ¯K+, Λ¯→p¯π+ events. The comparison of αΩ− and αΩ¯+ provides a test of CP invariance for Ω decays.