Properties ofΞ−andΞ0hyperons

Abstract

We report a measurement of the ${\Xi }^{-}$ and ${\Xi }^0$ weak-decay parameters, mean lifetimes, and spins, based on 4303 ${\Xi }^{-}$ and 652 ${\Xi }^0$ decays. We find for the ${\Xi }^{-}$, $\alpha =-0.376\mathrm{}\pm 0.038$, $\phi ={11}^{\circ }\pm 9^{\circ }$, $\tau =(1.63\mathrm{}\pm 0.03)\times {10}^{-10\mathrm{}}$ sec, and spin equal to ½ with higher spins excluded by more than 7 standard deviations; for the ${\Xi }^0$, $\alpha =-0.54\mathrm{}\pm 0.10$, $\phi ={16}^{\circ }\pm {17}^{\circ }$, $\tau =\left({2.88}_{-0.19\mathrm{}}^{+0.21\mathrm{}}\right)\times {10}^{-10\mathrm{}}$ sec, and spin equal to ½ with higher spins excluded by more than 4 standard deviations. The results are consistent with the requirements of $T$ invariance, and they are in fair agreement with the $\Delta I=\frac{1}{2}$ rule.