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The couplings of charmonia and charmonium hybrids (generically Psi) to ppbarare of great interest in view of future plans to study these states using anantiproton storage ring at GSI. These low to moderate energy Psi-ppbarcouplings are not well understood theoretically, and currently must bedetermined from experiment. In this letter we note that the two independentDirac (gamma_mu) and Pauli (sigma_munu) ppbar couplings of the J/psi and psi'can be constrained by the angular distribution of e+e- -> (J/psi, psi') ->ppbar on resonance. A comparison of our theoretical results to recentunpolarized data allows estimates of the ppbar couplings; in the betterdetermined J/psi case the data is inconsistent with a pure Dirac (gamma_mu)coupling, and can be explained by the presence of a sigma_munu term. This Paulicoupling may significantly affect the cross section of the PANDA process p pbar-> pi0 J/psi near threshold. There is a phase ambiguity that makes itimpossible to uniquely determine the magnitudes and relative phase of the Diracand Pauli couplings from the unpolarized angular distributions alone; we showin detail how this can be resolved through a study of the polarized reactions.

Evidence for a J/psi-ppbar Pauli Strong Coupling ?