Study of the reactions $\bar{n}p\to 2\ddot{I}{€}^{+}\ddot{I}{€}^{-}$, $2\ddot{I}{€}^{+}\ddot{I}{€}^{-}\ddot{I}{€}^0$, and $2\ddot{I}{€}^{+}\ddot{I}{€}^{-}2\ddot{I}{€}^0$ using $J/\ddot{I}ˆ\to p\ddot{I}{€}^{-}\bar{n}$

Abstract

We report an experimental investigation of the reactions $\bar{n}p\to 2\ddot{I}{€}^{+}\ddot{I}{€}^{-}$, $\bar{n}p\to 2\ddot{I}{€}^{+}\ddot{I}{€}^{-}\ddot{I}{€}^0$, and $\bar{n}p\to 2\ddot{I}{€}^{+}\ddot{I}{€}^{-}2\ddot{I}{€}^0$ using $(10.087\pm 0.044)\times 10^9$ $J/\ddot{I}ˆ$ events collected with the BESIII detector at the BEPCII storage ring. The antineutron ($\bar{n}$) is produced in the decay $J/\ddot{I}ˆ\to p\ddot{I}{€}^{-}\bar{n}$ with studied momentum from 200~MeV/$c$ to 1174~MeV/$c$, while the target proton originates from the hydrogen nuclei in the cooling oil of the beam pipe. This novel method pioneers the study of $\bar{n}$-nucleon interactions at an $e^{+}{e}^{-}$ collider, providing the first experimental data for $\bar{n}$ momenta exceeding 800~MeV/$c$.