Nucleon-nucleon cross sections in dense nuclear matter

We present microscopic calculations of cross sections for scattering of identical and nonidentical nucleons in symmetric nuclear matter at various densities, using the Brueckner-Hartree-Fock approximation scheme with the Argonne v(14) potential including the contribution of microscopic three-body forces. We investigate separately the effects of three-body forces on the effective mass and on the scattering amplitude. In the present calculation, the rearrangement contribution of the three-body force is considered, which reduces the neutron and proton effective mass and suppresses the magnitude of the cross section. The presence of "Z diagrams" in the three-body force enables us to make a comparison with the medium effects on the nucleon-nucleon cross sections obtained with the Dirac-Brueckner-Hartree-Fock approximation.