l - th / 9 61 20 40 v 1 1 6 D ec 1 99 6 Antikaon production in nucleon - nucleon reactions near threshold ∗

The antikaon production cross section from nucleon-nucleon reactions near threshold is studied in a meson exchange model. We include both pion and kaon exchange, but neglect the interference between the amplitudes. In case of pion exchange the antikaon production cross section can be expressed in terms of the antikaon production cross section from a pion-nucleon interaction, which we take from the experimental data if available. Otherwise, a K-resonance exchange model is introduced to relate the different reaction cross sections. In case of kaon exchange the antikaon production cross section is related to the elastic KN and K̄N cross sections, which are again taken from experimental measurements. We find that the one-meson exchange model gives a satisfactory fit to the available data for the NN → NNKK̄ cross section at high energies. We compare our predictions for the cross section near threshold with an earlier empirical parameterization and that from phase space models. Supported by BMBF, GSI Darmstadt and Forschungszentrum Jülich GmbH Permanent address: Cyclotron Institute and Physics Department, Texas A&M University, College Station, Texas 77843, USA