Paper detail

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

Using the CLEO II detector at the Cornell Electron Storage Ring we have measured the $Ξ_c^{0}$ decay asymmetry parameter in the decay $Ξ_c^{0} \to Ξ^{-} π^+$. We find $α_{Ξ_c^{0}} α_Ξ = 0.26 \pm 0.18{(stat)}^{+0.05}_{-0.04}{(syst)}$, using the world average value of $α_Ξ = -0.456 \pm 0.014$ we obtain $α_{Ξ_c^{0}} = -0.56 \pm 0.39{(stat)}^{+0.10}_{-0.09}{(syst)}$. The physically allowed range of a decay asymmetry parameter is $-1<α<+1$. Our result prefers a negative value: $α_{Ξ_c^{0}}$ 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.