One-pion-exchange final-state-interaction and the pbar p near threshold enhancement in J/psi -> gamma pbar p decays

Abstract

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