One-pion-exchange final-state interaction and the $p\overline{p}$ near threshold enhancement in $J/\overrightarrow{\psi }\gamma p\overline{p}$ decays

For the $N\overline{N}$ system, the one-pion-exchange (OPE) interaction gives the largest attractive force for $N\overline{N}$ with an isospin $I=0\mathrm{}$ and spin $S=0,$ while a near-threshold enhancement was observed for $p\overline{p}$ with $I=0\mathrm{}$ and $S=0\mathrm{}$ in $J/\overrightarrow{\psi }\gamma p\overline{p}$ decays. With a K-matrix approach, we find that the OPE final-state interaction makes an important contribution to the near-threshold enhancement in the $p\overline{p}$ mass spectrum in $J/\overrightarrow{\psi }\gamma p\overline{p}$ decays.