Probing the Effects of Density- and Momentum-dependent Potentials in Heavy Ion Collisions

The single-nucleon mean-field potential, in-medium nucleon–nucleon cross-sections, and initial density distributions of nucleons are obtained from the Skyrme nucleon-nucleon effective interaction, which are self-consistently used in the Boltzmann-Uehling-Uhlenbeck(BUU) transport model. The ^124\rmSn+^124\rmSn and ^112\rmSn+^112\rmSn reactions are simulated with BUU model using six sets of Skyrme parameters (SkI2, Gs, KDE0v1, NRAPR, BSk9, and SV-mas08) that predict different stiffnesses of the symmetry energy for two opposite choices of neutron-proton effective mass splitting. It is found that the effects of the neutron-proton effective mass splitting on double neutron-proton ratios are obvious at higher kinetic energies. In addition, among the six sets of interactions, the comparison with NSCL experimental data indicates that double neutron-proton ratios corresponding to the KDE0v1 interaction seem closer to the experimental data.