Polarization of theΣ0Particles Produced in the Reactionπ−+p→K0+Σ0at 1.5 and 1.8BeVc

The polarization of the ${\Sigma }^0$ particles produced in the reaction ${\pi }^{-}+p\to K^0+{\Sigma }^0$ has been measured at $1.5 \mathrm{and} 1.8 \frac{\mathrm{BeV}}{c}$, using a spark-chamber magnet system. The product ${\alpha }_{\Lambda }〈{\sigma }_{{\Sigma }^0}〉$ was found to be -0.47±0.33, +0.51±0.27, and +0.82±0.44, respectively, in ${\Sigma }^0$ c.m. angular intervals centered at $cos{\theta }^{*}=0.8,-014\mathrm{}$, and $0.0 \mathrm{at} 1.8 \frac{\mathrm{BeV}}{c}$; and -0.55±0.23, -0.31±0.38, and -0.82±0.46 at the same production angles at $1.5 \frac{\mathrm{BeV}}{c}$. The ${\Sigma }^0$ production angular distributions in the backward hemisphere at both momenta are also given. Both polarization and angular distribution are found to vary rapidly with energy.