Study of the Reactions n[over ¯]p→2π^{+}π^{-}, 2π^{+}π^{-}π^{0}, and 2π^{+}π^{-}2π^{0} Using J/ψ→pπ^{-}n[over ¯]

We report an experimental investigation of the reactions n[over ¯]p→2π^{+}π^{-}, n[over ¯]p→2π^{+}π^{-}π^{0}, and n[over ¯]p→2π^{+}π^{-}2π^{0} using (10.087±0.044)×10^{9}  J/ψ events collected with the BESIII detector at the BEPCII storage ring. The antineutron (n[over ¯]) is produced in the decay J/ψ→pπ^{-}n[over ¯] with studied momentum from 200 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 n[over ¯]-nucleon interactions at an e^{+}e^{-} collider, providing the first experimental data for n[over ¯] momenta exceeding 800  MeV/c.