Search for Structure inπ−p→ΛK0atΣKThreshold

Abstract

We have measured the cross section, the angular distribution, and the $\ensuremath{\Lambda}$ polarization for the reaction ${\ensuremath{\pi}}^{\ensuremath{-}}p\ensuremath{\rightarrow}\ensuremath{\Lambda}{K}^{0}$. A spark-chamber spectrometer was used to collect 8400 $\ensuremath{\Lambda}{K}^{0}$ events at fourteen beam momenta near $\ensuremath{\Sigma}K$ threshold. Our data do not show the prominent cross-section enhancement suggested by some previous experiments. However, detailed structure in the cross section and the angular distribution agrees well with a simple model which includes a cusp effect at $\ensuremath{\Sigma}K$ threshold.