CPNonconservation in Hyperon Decays

Upper bounds on rate differences between particle and antiparticle decays of hyperons are estimated in the standard six-quark model. For each of ${\Lambda }^0\to p{\pi }^{-}$, ${\Lambda }^0\to n{\pi }^0$, ${\Sigma }^{+}\to n{\pi }^{+}$, ${\Sigma }^{+}\to p{\pi }^0$ fractional rate differences of order ${10}^{-6\mathrm{}}$ are found whereas for ${\Sigma }^{-}\to n{\pi }^{-}$, ${\Xi }^{-}\to \Lambda {\pi }^{-}$, and ${\Xi }^0\to \Lambda {\pi }^0$ none is expected. Some other tests of $\mathrm{CP}$ conservation in hyperon decays relevant to left-right symmetric models are pointed out.