Study of anti-n.p -> phi.pi+ and anti-n.p -> omega.pi+ annihilation reactions in flight

The results of a study of the annihilation reactions and are reported; the data were collected by the OBELIX apparatus, with antineutrons annihilating in flight (momenta from ∼ 50 MeV/c to 405 MeV/c). Annihilation frequencies and annihilation cross sections have been deduced, for both channels, as a function of antineutron momentum. From the cross section ratio, a substantial deviation from OZI rule expectations is observed. An quark content in the nucleon offers a fairly plausible explanation for such an effect