Proton-antiproton annihilation in baryonium

A possible interpretation of the near-threshold enhancement in the (pp) mass spectrum in J/ψ→γpp is the existence of a narrow baryonium resonance X(1860). Mesonic decays of the (pp) bound state X(1860) because of the nucleon-antinucleon annihilation are investigated in this article. Mesonic coherent states with fixed G parity and P parity have been constructed. The Amado-Cannata-Dedoder-Locher-Shao formulation is extended to the decays of the X(1860). By this method, the branch-fraction ratios of Br(X→η4π),Br(X→η2π), and Br(X→3η) are calculated. It is shown that if the X(1860) is a bound state of (pp), the decay channel (X→η4π) is favored over (X→η2π). In this way, we develop criteria for distinguishing the baryonium interpretation for the near-threshold enhancement effects in the (pp) mass spectrum in J/ψ→γpp from other possibilities. Experimental checks are expected. An intuitive picture for our results is discussed