A Measurement of the Decay Asymmetry Parameters in \Xi_{c}^{0}\to \X^{-}\pi^{+}

Using the CLEO II detector at the Cornell Electron Storage Ring we have measured the $\Xi_c^{0}$ decay asymmetry parameter in the decay $\Xi_c^{0} \to \Xi^{-} \pi^+$. We find $\alpha_{\Xi_c^{0}} \alpha_{\Xi} = 0.26 \pm 0.18{(stat)}^{+0.05}_{-0.04}{(syst)}$, using the world average value of $\alpha_{\Xi} = -0.456 \pm 0.014$ we obtain $\alpha_{\Xi_c^{0}} = -0.56 \pm 0.39{(stat)}^{+0.10}_{-0.09}{(syst)}$. The physically allowed range of a decay asymmetry parameter is $-1<\alpha<+1$. Our result prefers a negative value: $\alpha_{\Xi_c^{0}}$ 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.Comment: 10 pages postscript, also available through http://w4.lns.cornell.edu/public/CLN

Observation of the Cabibbo-suppressed charmed baryon decay Λ_c⁺→pφ

We report the observation of the Cabibbo-suppressed decays Λ&lt;sub&gt;c&lt;/sub&gt;&lt;sup&gt;+&lt;/sup&gt;→pK&lt;sup&gt;-&lt;/sup&gt;K&lt;sup&gt;+&lt;/sup&gt; and Λ&lt;sub&gt;c&lt;/sub&gt;&lt;sup&gt;+&lt;/sup&gt;→pφ using data collected with the CLEO II detector at CESR. The latter mode, observed for the first time with significant statistics, is of interest as a test of color suppression in charm decays. We have determined the branching ratios for these modes relative to Λ&lt;sub&gt;c&lt;/sub&gt;&lt;sup&gt;+&lt;/sup&gt;→pK&lt;sup&gt;-&lt;/sup&gt;K&lt;sup&gt;+&lt;/sup&gt; and compared our results with theory