Revisiting the proton-antiproton scattering using a constituent-quark-model based coupled-channels calculation

Motivated by the last experimental and theoretical advances in the analysis of possible baryonium resonances, the X(1835) and their partners, we perform a constituent-quark-model based coupled-channels calculation of the proton-antiproton scattering in order to analyze the possible existence of bound states or near-threshold structures. The used NN‾ potential is derived from a G-parity transformation of the quark-model-based NN interaction which has described well deuteron properties, NN phase shifts, and even hadron-hadron phenomenology. The additional NN‾ annihilation is taken into account by a complex phenomenological potential whose real part is generated by one-pion and one-gluon exchange annihilation potentials and its imaginary part is an energy-independent potential of Gaussian form. Then, all the parameters of the interaction are constrained by the NN sector except those determining the imaginary part of the annihilation potential. Our study concludes that the nucleon-antinucleon dynamics is complex and rich in scattering singularities near the proton-antiproton and neutron-antineutron thresholds.