First observation ofψ(2S)→pn¯π−+c.c

Using $14\ifmmode\times\else\texttimes\fi{}{10}^{6}$ $\ensuremath{\psi}(2S)$ events collected with the Beijing Spectrometer (BESII) at the Beijing Electron-Positron Collider, the branching fractions of $\ensuremath{\psi}(2S)$ decays to $p\overline{n}{\ensuremath{\pi}}^{\ensuremath{-}}$ and $\overline{p}n{\ensuremath{\pi}}^{+}$ and the branching fractions of the main background channels $\ensuremath{\psi}(2S)\ensuremath{\rightarrow}p\overline{n}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{0}$, $\ensuremath{\psi}(2S)\ensuremath{\rightarrow}\ensuremath{\gamma}{\ensuremath{\chi}}_{c0}\ensuremath{\rightarrow}\ensuremath{\gamma}p\overline{n}{\ensuremath{\pi}}^{\ensuremath{-}}$, $\ensuremath{\psi}(2S)\ensuremath{\rightarrow}\ensuremath{\gamma}{\ensuremath{\chi}}_{c2}\ensuremath{\rightarrow}\ensuremath{\gamma}p\overline{n}{\ensuremath{\pi}}^{\ensuremath{-}}$, and $\ensuremath{\psi}(2S)\ensuremath{\rightarrow}\ensuremath{\gamma}{\ensuremath{\chi}}_{cJ}\ensuremath{\rightarrow}\ensuremath{\gamma}p\overline{n}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{0}$ are determined. The contributions of the ${N}^{*}$ resonances in $\ensuremath{\psi}(2S)\ensuremath{\rightarrow}p\overline{n}{\ensuremath{\pi}}^{\ensuremath{-}}+c.c.$ are also discussed.