KAON PRODUCTION IN NUCLEUS-NUCLEUS COLLISIONS - EQUATION OF STATE, MOMENTUM DEPENDENCE AND RELATIVISTIC EFFECTS

We investigate the production of K+ mesons in nucleus-nucleus collisions from 700 MeV/A to 2500 MeV/A within a fully Lorentz covariant (RQMD) and a non-covariant (QMD) quantum molecular dynamics. A Skyrme-type mean field is employed in the classical Hamilton equations of motion. The parameters of this potential are adjusted so that we have two different equations of state: a soft one with incompressibility K = 200 MeV and a hard one with K = 380 MeV. In the QMD we include also a phenomenological momentum dependence in the in-medium nucleon-nucleon (NN) interaction. A parametrized cross section is used for K+ production in elementary baryon-baryon collisions (B1 + B2 --> B + Y + K+). We make detailed comparisons among the theoretical results obtained in the QMD and RQMD, with different nuclear equations of state, with and without the momentum dependence in the NN interaction and with different parametrizations for the elementary cross section. The theoretical K+ production cross sections obtained in the RQMD are in good agreement with available experimental data for Ne-20 + NaF at 2100 MeV/A and Si-28 + Si-28 at 2000 MeV/A, except for the high momentum tail of the kaon spectrum.