Baryonium, a common ground for atomic and high energy physics

TL;DR

This paper discusses experimental evidence and theoretical interpretations of quasi-bound states in the nucleon-antinucleon system, suggesting a common underlying baryonium state relevant to both atomic and high energy physics.

Contribution

It presents new experimental observations of enhancements near the p-pbar threshold and interprets them within the Paris potential model, proposing a unified baryonium state.

Findings

Observation of broad enhancement near p-pbar threshold in J/psi decays

Identification of a narrower state about 50 MeV below threshold

Support from antiprotonic atomic data for the baryonium interpretation

Abstract

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.