First Study of Reaction Ξ0n → Ξ-p Using Ξ0 -Nucleus Scattering at an Electron-Positron Collider

Using (1.0087±0.0044)×1010 J/ψ events collected with the BESIII detector at the BEPCII storage ring, the process Ξ0n→Ξ-p is studied, where the Ξ0 baryon is produced in the process J/ψ→Ξ0Ξ¯0 and the neutron is a component of the Be9, C12, and Au197 nuclei in the beam pipe. A clear signal is observed with a statistical significance of 7.1σ. The cross section of the reaction Ξ0+Be9→Ξ-+p+Be8 is determined to be σ(Ξ0+Be9→Ξ-+p+Be8)=(22.1±5.3stat±4.5sys) mb at the Ξ0 momentum of 0.818 GeV/c, where the first uncertainty is statistical and the second is systematic. No significant H-dibaryon signal is observed in the Ξ-p final state. This is the first study of hyperon-nucleon interactions in electron-positron collisions and opens up a new direction for such research.