Screening effects on the elastic nucleon-nucleon cross section in relativistic nuclear matter

We investigate the screening effects on the nucleon-nucleon elastic cross section inside nuclear matter at zero and finite temperature. The N-N interaction is described phenomenologically via meson exchanges ($\sigma$, $\pi$ and $\omega$) in the framework of a relativistic lagrangian model. The expressions for the in-medium meson propagators, which take into account the effects of matter polarization and renormalized vacuum polarization, are used in the calculation of the various meson contributions to the total cross section in the one-boson exchange approximation. The final expressions allow a satisfactory fit of the Coulomb substracted proton-proton cross section data in vacuum. At finite density or temperature the cross section is reduced as compared to the vacuum values and compatible with the existing experimental constraints. At high density the $p$-$p$ differential cross section gets increasingly forward and backward peaked. The $\sigma$-$\omega$ mixing plays a key role in the understanding of the results.