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

Abstract

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 (σ, π and ω) 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 σ-ω mixing plays a key role in the understanding of the results.

Nucleon–nucleon effective potential in dense matter including rho-meson exchange

“…1 Our claim is that RPA may give important effects, both quantitative and qualitative, and has to be considered in many-body calculations of nuclear matter. As a matter of fact, it was shown [13] that RPA corrections give rise to a modification of the in-medium cross section of the same order of magnitude as Brueckner ones, and compatible with experimental data available so far. Other examples are the reduction of neutrino opacities in neutron star matter from RPA corrections of the NN interaction [14,15] and the measurement of the electromagnetic response function in quasielastic electron scattering experiments [16].…”

Influence of differential elastic nucleon-nucleon cross section on stopping and collective flow in heavy-ion collisions at intermediate energies

“…Indeed, the angular dependence of the cross section can be modified by the in-medium effects, and this modification is model dependent (e.g. Refs [40,41,51]). …”

“…Refs [51]). To consider the uncertainty of the in-medium differential cross section, three commonly used differential NN cross sections in transport models are adopted and given as follows:…”

Enhancement of nucleon-nucleon cross section in sidewards flowing nuclear matter through zero sound mode excitation

“…for the mixing, longitudinal and transverse parts. The explicit expression for the polarizations and a study of the dispersion relations can found in [11,13]. Besides the σ and longitudinal and transverse ω branches, there is a zero sound branch in the mixed σ-ω mode.…”

“…The concern of our present work is to release this assumption. We refer the reader to [11] for details on the formalism and only recall here the main formulaes.…”