KAON FLOW IN HEAVY-ION COLLISIONS

Using the relativistic transport model that includes explicitly the kaon degree of freedom, we investigate kaon flow, i.e. the average kaon transverse momentum as a function of rapidity and the associated Bow parameter in both Au+Au collisions at 1 GeV/nucleon and Ni+Ni collisions at 1.45 GeV/nucleon. We also study the proton and pion flows in these collisions. For the proton flow in Au+Au collisions, our results using the non-linear sigma-omega model for the nucleon mean-field potential are in reasonable agreement with preliminary data from the EOS collaboration, For pions, which are treated without a mean-field potential, we observe clearly a transition of their flow from being parallel to anti-parallel to the nucleon Bow when the two ions change from central to semi-central and peripheral collisions. For kaons, we use four different assumptions for their potential in nuclear matter, i.e. without potential, the potential based on mean-field approximation to an effective chiral Lagrangian, the potential obtained in impulse approximation using the KN scattering length, and the potential containing only the repulsive vector interaction. It is found that the pattern of kaon flow in heavy-ion collisions is sensitive to the kaon potential used in the model and thus provides a useful means for studying kaon properties in nuclear medium.