Production of the 1385-MeV ${\left({Y_1}^{*}\right)}^0$ in 1.5-BeV/c ${\pi }^{-}p$ Interactions

The reaction 1.508-BeV/c ${\pi }^{-}+p\to K^0+\Lambda +{\pi }^0$ has been studied in a spark chamber experiment; 127 events of this type were obtained. The reaction is dominated by production of the ${\left({Y_1}^{*}\right)}^0$, with parameters $M_0=1381\mathrm{}\pm 4$ MeV, $\Gamma =30\mathrm{}\pm 9$ MeV. The differential cross section for production of the ${\left({Y_1}^{*}\right)}^0$ is $(6.3\mathrm{}\pm 0.9)\times [1+(0.15\mathrm{}\pm 0.27)cos\theta -(0.35\mathrm{}\pm 0.38\left){cos}^2\theta \right]$ μb/sr; the total production cross section is (70±11) μb. Decay distributions of this resonance, assuming $S$ and $P$ waves in the production, are consistent with spin $\frac{3}{2}$, favoring it over spin $\frac{5}{2}$ with a likelihood ratio of $\frac{10}{1}$.