A Measurement of the Decay Asymmetry Parameters in $Ξ_{c}^{0}\to \X^{-}π^{+}$

Abstract

Using the CLEO II detector at the Cornell Electron Storage Ring we have measured the $\hat{I}{ž}_c^0$ decay asymmetry parameter in the decay $\hat{I}{ž}_c^0\to \hat{I}{ž}^{-}\ddot{I}{€}^{+}$. We find $\hat{I}{\pm }_{\hat{I}{ž}_c^0}\hat{I}{\pm }_{\hat{I}}ž=0.26\pm 0.18{(stat)}_{-0.04}^{+0.05}(syst)$, using the world average value of $\hat{I}{\pm }_{\hat{I}}ž=-0.456\pm 0.014$ we obtain $\hat{I}{\pm }_{\hat{I}{ž}_c^0}=-0.56\pm 0.39{(stat)}_{-0.09}^{+0.10}(syst)$. The physically allowed range of a decay asymmetry parameter is $-1<\hat{I}\pm <+1$. Our result prefers a negative value: $\hat{I}{\pm }_{\hat{I}{ž}_c^0}$ is $<0.1$ at the 90% CL. The central value occupies the middle of the theoretically expected range but is not yet precise enough to choose between models.

10 pages postscript, also available through http://w4.lns.cornell.edu/public/CLNS