Measurement of the Double-Charge-Exchange Reactions ${\pi }^{-}p\to K^{+}{\Sigma }^{-}$ and $K^{-}p\to {\pi }^{+}{\Sigma }^{-}$

The forward cross sections for the reactions ${\pi }^{-}p\to K^{+}{\Sigma }^{-}$ and $K^{-}p\to {\pi }^{+}{\Sigma }^{-}$ have been determined for incident particle momenta in the range of 2.75 to 3.50 GeV/c, and an upper limit was established at 5.00 GeV/c. These measurements show that the double-charge-exchange process ${\pi }^{-}p\to K^{+}{\Sigma }^{-}$ is suppressed by a factor of 1500 at 3 GeV/c relative to the single-exchange reaction ${\pi }^{+}p\to K^{+}{\Sigma }^{+}$.