In-medium $\mbox{NN}\to \mbox{N}\Delta$ cross section and its dependence on effective Lagrange parameters in isospin-asymmetric nuclear matter

TL;DR

This study investigates how the in-medium $NN\rightarrow N\Delta$ cross section varies with density and isospin asymmetry using a one-boson exchange model, revealing suppression and isotropization effects at higher densities.

Contribution

It introduces a detailed analysis of the in-medium $NN\rightarrow N\Delta$ cross section considering isovector mesons and effective Lagrangian parameters, highlighting the dependence on density and effective mass.

Findings

Cross sections are suppressed with increasing density.

Differential cross sections become isotropic at higher densities.

Medium correction factor depends on effective mass.

Abstract

The in-medium $NN\rightarrow N\Delta$ cross section and its differential cross section in isospin asymmetric nuclear medium are investigated in the framework of the one-boson exchange model by including the isovector mesons, i.e., $\delta$ and $\rho$ mesons. Our results show that the in-medium $NN\rightarrow N\Delta$ cross sections are suppressed with density increasing, and the differential cross sections become isotropic with the density increasing at the beam energy around the $\Delta$ threshold energy. The isospin splitting on the medium correction factor, $R=\sigma_{ NN\rightarrow N\Delta}^*/\sigma_{NN\rightarrow N\Delta}^{\text{free}}$ is observed for different channels of $NN\to N\Delta$, especially around the threshold energy for all the effective Lagrangian parameters. By analyzing the selected effective Lagrangian parameters, our results show that the larger effective mass is, the weaker medium correction $R$ is.