Total cross sections, angular distributions, and polarization distributions have been measured for the reactions ${\pi }^{-}p\to {\Lambda }^0{K}^0$ and ${\pi }^{-}p\to {\Sigma }^0{K}^0$ at beam momenta of 1.12, 1.23, 1.27, and 1.32 BeV/c. Legendrepolynomical expansion coefficients for angular distributions and polarization distributions are presented and compared with other data. Two approximate cross-section equalities are demonstrated among $I=\frac{1}{2}$ total cross sections over a wide range of energies: ${\sigma }_{I=\frac{1}{2}}\left(\Sigma K\right)\cong \sigma \left(\Lambda K\right)$, and $\sigma \left(\eta N\right)\cong \sigma \left(\Lambda K\right)+{\sigma }_{I=\frac{1}{2}}\left(\Sigma K\right)$ where $\sigma \left(\eta N\right)$ is the total cross section for ${\pi }^{-}p\to \eta n$. Hyperon decay asymmetries observed in the reaction ${\pi }^{-}p\to \Lambda K^0$ are difficult to reconcile with a value of ${\alpha }_{\Delta }=0.66\mathrm{}$.

• Received 6 November 1968

DOI:https://doi.org/10.1103/PhysRev.183.1134