Observation of parity violation in the Ω−→ΛK−Ω−→ΛK− decay

The α decay parameter in the process Ω−→ΛK−Ω−→ΛK− has been measured from a sample of 4.50 million unpolarized Ω−Ω− decays recorded by the HyperCP (E871) experiment at Fermilab and found to be [1.78±0.19(stat)±0.16(syst)]×10−2[1.78±0.19(stat)±0.16(syst)]×10−2. This is the first unambiguous evidence for a nonzero α decay parameter, and hence parity violation, in the Ω−→ΛK−Ω−→ΛK− decay.