New measurement of theΛhelicity in the decayΞ0→Λπ0

Abstract

A sample of 6075 decays of unpolarized ${\Xi }^0$ hyperons has been obtained in the Fermilab neutral-hyperon beam. All decay products from the sequence ${\Xi }^0\to {\pi }^0\Lambda$, ${\pi }^0\to \gamma \gamma$, $\Lambda \to p{\pi }^{-}$ were detected. Analysis of the proton asymmetry in the $\Lambda$ decay gave ${\alpha }_{{\Xi }^0}{\alpha }_{\Lambda }=-0.317\mathrm{}\pm 0.027$ or ${\alpha }_{{\Xi }^0}=-0.490\mathrm{}\pm 0.042$. A comparison with the world average for ${\alpha }_{{\Xi }^{-}}$ gives a $\Delta I=\frac{3}{2}$ amplitude of 25 ± 9%.