Y1*(1385 MeV): Study of Spin and Parity by Moment Analysis for J=52, 32, and 12

Abstract

The possibility that the ${Y_1}^{*}(1385-\mathrm{MeV})$ spin is $\frac{5}{2}$ has been investigated. Identification of the ${Y_1}^{*}$ as an $F_{\frac{5}{2}}$ state is excluded; the $D_{\frac{5}{2}}$ assignment is not required; and $J=\frac{5}{2}$ is found rather unlikely. Of the states $P_{\frac{3}{2}}$, $D_{\frac{3}{2}}$, $S_{\frac{1}{2}}$, and $P_{\frac{1}{2}}$, only $P_{\frac{3}{2}}$ is acceptable, the excluded hypotheses having confidence levels of order ${10}^{-6\mathrm{}}$ or ${10}^{-7\mathrm{}}$; this conclusion strengthens slightly the authors' earlier selection of $P_{\frac{3}{2}}$, based chiefly on study of the ${\theta }_{\Lambda }$ dependence of two components of the decay $\Lambda \text{'}\mathrm{s}$ polarization. This more definitive report results from the application of the "moment analysis" of Byers and Fenster to a sample of 895 ${Y_1}^{*}$ decays obtained from $K^{-}-p$ interactions in the 72-in. bubble chamber.