${[\alpha\mathrm {({{\boldsymbol \Xi}^{-}})}\alpha_-({{\boldsymbol \Lambda}}) − \alpha\mathrm {({{\overline{\boldsymbol \Xi}}^{+}})}\alpha_+({{\overline{\boldsymbol \Lambda}}})]\over [\alpha\mathrm {({{\boldsymbol \Xi}^{-}})}\alpha_-({{\boldsymbol \Lambda}}) + \alpha\mathrm {({{\overline{\boldsymbol \Xi}}^{+}})}\alpha_+({{\overline{\boldsymbol \Lambda}}})]}$
INSPIRE search
This is zero if $\mathit CP$ is conserved. The $\alpha $'s are the decay-asymmetry parameters for ${{\mathit \Xi}^{-}}$ $\rightarrow$ ${{\mathit \Lambda}}{{\mathit \pi}^{-}}$ and ${{\mathit \Lambda}}$ $\rightarrow$ ${{\mathit p}}{{\mathit \pi}^{-}}$ and for ${{\overline{\mathit \Xi}}^{+}}$ $\rightarrow$ ${{\overline{\mathit \Lambda}}}{{\mathit \pi}^{+}}$ and ${{\overline{\mathit \Lambda}}}$ $\rightarrow$ ${{\overline{\mathit p}}}{{\mathit \pi}^{+}}$ .
