The in-medium neutron-proton, proton-proton (neutron-neutron) elastic scattering cross sections $\left({\sigma }_{np}^{*},{\sigma }_{pp\left(nn\right)}^{*}\right)$ are studied based on the effective Lagrangian of density dependent relativistic hadron theory in which the $\delta \left[a_0\left(980\right)\right]$ meson is included. Our study shows that at low densities the ${\sigma }_{np}^{*}$ is about three to four times larger than ${\sigma }_{pp\left(nn\right)}^{*}$ and at densities higher than the normal density the isospin effect is almost washed out. Because of coupling to $\delta$ meson the ${\sigma }_{nn}^{*}$ and ${\sigma }_{pp}^{*}$ are different in isospin asymmetric medium following the splitting of the proton and neutron masses. The isospin effect on the density dependence of the in-medium nucleon elastic cross section is dominantly contributed by the isovector $\delta$ and $\rho$ mesons. The temperature effect on the ${\sigma }_{np}^{*}$ and ${\sigma }_{pp\left(nn\right)}^{*}$ is studied. It is shown that the temperature effect is weaker compared with the density effect but it becomes obvious as density increases.

• Received 18 August 2003

DOI:https://doi.org/10.1103/PhysRevC.69.017601