In-medium nucleon-nucleon cross sections from nonrelativistic reaction matrices in nuclear matter

In-medium nucleon-nucleon cross sections are calculated from reaction matrices of the nonrelativistic Brueckner approach. Calculated cross sections are parametrized as a function of the incident energy and the nuclear density. The nonrelativistic cross sections are found to be reduced from free ones as observed in relativistic Brueckner calculations. This reduction of the in-medium cross sections is ascribed to the flux renormalization represented by an effective mass. It is pointed out that we should be careful to avoid double counting the effective mass effects when in-medium cross sections calculated are applied in various models of dynamical nuclear processes.