The near-threshold enhancement in the p p-bar invariant mass spectrum of the reaction J/Psi --> gamma p p-bar, observed in an experiment by the BES Collaboration, is analysed. It is shown, within the Watson-Migdal approach to final state interactions, that the mass dependence of the p p-bar spectrum close to the threshold can be reproduced by the S-wave p p-bar interaction of the Jülich N N-bar model in the isospin I=1 state. Difficulties in the consistent interpretation of the p invariant mass spectrum of the reaction J/Psi --> pi^0 p p-bar, where there are no obvious signs for a final state interaction, are discussed.

The near-threshold enhancement in the p p-bar invariant mass spectrum of the reaction J/Psi --> gamma p p-bar, observed in an experiment by the BES Collaboration, is analysed. It is shown, within the Watson-Migdal approach to final state interactions, that the mass dependence of the p p-bar spectrum close to the threshold can be reproduced by the S-wave p p-bar interaction of the Jülich N N-bar model in the isospin I=1 state. Difficulties in the consistent interpretation of the p invariant mass spectrum of the reaction J/Psi --> pi^0 p p-bar, where there are no obvious signs for a final state interaction, are discussed.

We investigate the nature of the near-threshold enhancement in the p {bar p} invariant mass spectrum of the reaction J/[Psi] → [gamma] p {bar p} reported recently by the BES Collaboration. Using the Juelich N {bar N} model we show that the mass dependence of the p {bar p} spectrum close to the threshold can be reproduced by the S-wave p {bar p} final state interaction in the isospin I=1 state within the Watson-Migdal approach. However, because of our poor knowledge of the N {bar N} interaction near threshold and of the J/[Psi] → [gamma] p {bar p} reaction mechanism and in view of the controversial situation in the decay J/[Psi] → [pi]° p {bar p}, where no obvious signs of a p {bar p} final state interaction are seen, explanations other than final state interactions cannot be ruled out at the present stage.

We observe a narrow enhancement near 2m[sub p] in the invariant mass spectrum of p[bar p] pairs from radiative J/[psi][yields][gamma]p[bar p] decays. No similar structure is seen in J/[psi][yields][pi][sup 0] p[bar p] decays. The results are based on an analysis of a 58 million event sample of J/[psi] decays accumulated with the BESII detector at the Beijing electron-positron collider. The enhancement can be fit with either an S- or P-wave Breit Wigner resonance function. In the case of the S-wave fit, the peak mass is below 2m[sup p] at M= 1859[sub -10][sup+3] (stat)[sub -25][sup+5] (sys) MeV/c[sup 2] and the total width is[Lambda]

We present an update of the study of the Y(4260) resonance, produced in the process ee− →?{sub ISR}?+?− J/? using initial-state radiation events at the PEP-II e+e− storage rings. This study is based on 454 fb−1 of data recorded with the BABAR detector at a center-of-mass energy in the?(4S) resonance region. From a fit with a single non-relativistic Breit-Wigner shape we obtain updated parameters for the Y(4260) resonance which are m{sub Y} = 4252 ± 6−3{sup +2} MeV/c2 and?{sub Y} = 105 ± 18−6{sup +4} MeV/c2; we also measure?(?+?− J/?)?{sub e{sup +}e−} = (7.5 ± 0.9 ± 0.8) eV. We cannot confirm the recent BELLE observation of a broad structure around 4.05GeV/c2 in this decay mode.