Precise measurement of the asymmetry parameter in the decayΞ0→Λπ0

Abstract

The $\Lambda$ helicity has been measured in a fully reconstructed sample of 3.0×${10}^5$ ${\Xi }^0\to \Lambda {\pi }^0$ decays. The product ${\alpha }_{\Lambda }{\alpha }_{{\Xi }^0}$ was found to be -0.260±0.006, or ${\alpha }_{{\Xi }^0}=-0.405\mathrm{}\pm 0.011$.