Study ofK−andK¯0Meson Stars in Emulsion

108 $K^{-}$ stars were found by area-scanning. The secondaries were followed and the hyperons were analyzed. The lifetime for ${\Sigma }^{+}\to p+{\pi }^0$ is (${1.38}_{-0.63\mathrm{}}^{+1.39\mathrm{}}$)×${10}^{-10\mathrm{}}$ sec and for ${\Sigma }^{\pm }\to n+{\pi }^{\pm }$ is (${0.31}_{-0.10\mathrm{}}^{+0.32\mathrm{}}$)×${10}^{-10\mathrm{}}$ sec. The latter figure is apparently in disagreement with the bubble chamber data on lifetimes of hyperons. Two events which were caused by ${\overline{K}}^0$ mesons are described.