Probing the momentum dependence of medium modifications of the nucleon-nucleon elastic cross sections

TL;DR

This study investigates how the momentum dependence of medium modifications affects nucleon-nucleon elastic cross sections and their impact on observables like nucleon yields and elliptic flow in heavy-ion collisions, using microscopic transport models.

Contribution

It provides a detailed analysis of the momentum dependence of medium modifications on nucleon-nucleon cross sections and their influence on collision observables, highlighting the importance of elliptic flow.

Findings

Elliptic flow is highly sensitive to the momentum dependence of medium modifications.

Uncertainties in the momentum dependence affect nucleon yields and collective flows.

Elliptic flow can help distinguish the mass splitting effect at high densities.

Abstract

The momentum dependence of the medium modifications on nucleon-nucleon elastic cross sections is discussed with microscopic transport theories and numerically investigated with an updated UrQMD microscopic transport model. The semi-peripheral Au+Au reaction at beam energy $E_b=400A$ MeV is adopted as an example. It is found that the uncertainties of the momentum dependence on medium modifications of cross sections influence the yields of free nucleons and their collective flows as functions of their transverse momentum and rapidity. Among these observables, the elliptic flow is sensitively dependent on detailed forms of the momentum dependence and more attention should be paid. The elliptic flow is hardly influenced by the probable splitting effect of the neutron-neutron and proton-proton cross sections so that one might pin down the mass splitting effect of the mean-field level at high beam energies and high nuclear densities by exploring the elliptic flow of nucleons or light clusters.