Meson cloud in the nucleon and anti d- anti u asymmetry from the Drell-Yan processes

Mesonic models predict violation of the SU(2) symmetry in the nucleon sea which seems to be necessary to explain the violation of the Gottfried sum rule. At the present time there is no generally accepted explanation of the effect. We find that careful analysis of the Drell-Yan processes in pp and pn collisions will provide complementary data to the Gottfried sum rule on the anti d- anti u asymmetry. We also find that some combinations of experimental results are insensitive to details of the mesonic models, offering the possibility to demonstrate the existence of the mesonic cloud in the nucleon. (orig.)