Based on 1.35 million polarized Ξβ events, we measure the parameter
ΟΞβ to be β1.61βΒ±2.66βΒ±0.37β for
ΞββΞΟβ decay. New results for the parameters
Ξ²Ξβ and Ξ³Ξβ are also presented. Assuming that the
CP-violating phase-shift difference is negligible, we deduce the strong
phase-shift difference between the P-wave and S-wave amplitudes of the
ΞΟ final state to be 3.17βΒ±5.28βΒ±0.73β. This strong phase-shift difference reduces the theoretical
uncertainty in estimating the level of CP violation in Ξ-hyperon decay.Comment: To be published in Physical Review Letter