Optical potentials for the antiproton nucleus interactions

The nuclear interactions of atomic and low energy antiprotons are studied. Measurements of level shifts and widths in the lightest elements are analyzed and compared with new results obtained in heavy nuclei. Simple geometric properties of antiproton - nucleus interactions are demonstrated. Upon this background one finds some anomalies that indicate strong energy dependence in the subthreshold antiproton - nucleon interactions. The use of of antiproton in studies of the nuclear surface is briefly discussed.Comment: 10 pages, 2 figures, LaTeX2e espcrc1 style, LEAP 2000 Conference, Venice, Italy, to be published in Nucl. Phys. Proc. Supp

The antinucleon-nucleon quasi-bound states: J/psi and atomic evidence

The measurements of J/psi decays into photon, proton and antiproton show a strong enhancement at the proton-antiproton threshold not seen in the decays into neutral pion, proton and antiproton. What is the nature of this enhancement? A natural interpretation can be performed in terms of a classical model of nucleon-antinucleon interactions based on G-parity transformation. The observed proton-antiproton structure is the consequence of the strong attraction in the singlet S-wave state related predominantly to pion exchanges. Similar attractions generate near threshold: an isospin-zero virtual (or quasi-bound) state in singlet S-wave, an isospin-one quasi-bound state in triplet P-wave with total angular momentum one and an isospin-zero resonance in triplet P-wave with total angular momentum zero. These P-wave structures find support in the antiproton-atomic data.Comment: 7 pages, 3 eps figures. Invited talk (S. Wycech) to the International Conference on Low Energy Antiproton Physics (LEAP05), May 16-22, 2005, Bonn-Juelich, Germany, to appear in AIP series of conference proceeding

Baryonium, a common ground for atomic and high energy physics

Indications of the existence of quasi-bound states in the N-Nbar system are presented. Measurements by BES discovered a broad enhancement close to the p-pbar threshold in the S wave, isospin 0 state formed in radiative decays of J/psi. Another enhancement located about 50 MeV below the threshold was found in mesonic decays of J/psi. In terms of the Paris potential model it was shown that these are likely to represent the same state. Antiprotonic atomic data provide some support for this interpretation and indicate the existence of another fairly narrow quasi-bound state in a P wave.Comment: 6 pages, 6 figures - Contribution to EXA2014 Vienna to appear in a special edition of Hyperfine Interaction