Isospin dependence of nucleon-nucleon elastic cross section

The in-medium neutron-proton, proton-proton (neutron-neutron) scattering cross sections (σ_np^*, σ_pp(nn)^*) are studied based on QHD-II type Lagrangian within the framework of the microscopic transport theory. The results demonstrate that, for free nucleon-nucleon scattering cross sections, the isospin dependence is dominantly caused by the ρ meson field. The medium correction of nucleon-nucleon scattering cross sections is also isospin dependent, σ_np^* depends on the baryon density weakly and σ_pp(nn)^* depends on the baryon density significantly, which is due to the different effects of the medium correction of nucleon mass and ρ meson mass on σ_np and σ_pp(nn), respectively.