Bound and resonant states in the nucleon-antinucleon system

A possibility of existence of relatively long-living quasinuclear states of the N anti N system was shown theoretically earlier. The modern states of the problem is reviewed. γ radiation accompanies the annihilation of antiprotons. This radiation is found in anti p d annihilation. There are anomalies in annihilation of slow antiprotons. Rather intensive annihilation from triplet p states of anti pp and anti pd atoms is observed as well as deviation from the 1/v low for slow anti p. There was direct discovery of heavy ''quasinuclear'' anti NN mesons. Resonant N anti N states are seen in the energy behaviour of the anti pp and pd total cross sections and in the large angle anti pp elastic scattering cross sections