The α decay parameter in the process Ω -→ΛK- has been measured from a sample of 4.50 million unpolarized Ω- decays recorded by the HyperCP (E871) experiment at Fermilab and found to be [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- decay. © 2005 Elsevier B.V. All rights reserved.
