Search for ΔS = 2 decays of neutral Ξ-hyperons

A search for the decay Ξ⁰→pπ^? has been performed in a neutral hyperon beam derived from the 24 GeV/c external proton beam at CERN. The experiment gives as a 90% confidence upper limit for the branching ratio $\text{Γ(Ξ}{}^0\text{→pπ}{}^{\mathrm{?}}\text{)}\text{Γ(Ξ}{}^0\text{→Λπ}{}^0\text{)<3.6×10}{}^{\mathrm{?5}}$.