Accessing the in-medium effects on nucleon-nucleon elastic cross section with collective flows and nuclear stopping

TL;DR

This study investigates how in-medium modifications of nucleon-nucleon elastic cross sections affect collective flow and nuclear stopping in heavy-ion collisions, revealing energy-dependent sensitivities and deriving correction factors from experimental data.

Contribution

It introduces an energy-dependent in-medium correction factor for nucleon-nucleon cross sections within the UrQMD model, linking it to observable flow and stopping data.

Findings

Flow and stopping are highly sensitive to the correction factor at low energies.

Sensitivity to the correction factor decreases with increasing beam energy.

An energy-dependent correction factor is extracted from experimental data.

Abstract

A systematic study of the in-medium correction factor ($F$) on nucleon-nucleon elastic cross section is performed within the Ultra-relativistic Quantum Molecular Dynamics (UrQMD) model. The effects of the beam energy dependence of $F$ on the directed, elliptic flow and nuclear stopping in $^{197}$Au+$^{197}$Au collisions with energy ranging from $0.09$ to $0.8A$ GeV are explored. It is found that the directed, elliptic flow and nuclear stopping at relatively low energies are very sensitive to $F$, and the sensitivity gradually weakens with increasing beam energy. The beam energy dependent in-medium correction factor $F$ is deduced from the comparison of the excitation functions of the directed, elliptic flow and nuclear stopping between the calculated results and the FOPI experimental data.