Quark-Meson Coupling Model in Heavy-Ion Collision Simulations

TL;DR

This paper integrates the quark-meson coupling (QMC) model into a transport code to simulate heavy-ion collisions, showing comparable results to traditional models and highlighting differences in pion production predictions.

Contribution

The work implements the QMC model within a transport simulation framework and compares its predictions to QHD, demonstrating its effectiveness in heavy-ion collision modeling.

Findings

QMC and QHD yield similar bulk observable results in Au+Au collisions.

Reproducing pion yields with QMC requires adjusting in-medium $ ext{Delta}$ production cross-section.

QMC can be effectively used in transport simulations for heavy-ion collisions.

Abstract

The quark-meson coupling (QMC) model incorporates quark degrees of freedom into the relativistic mean-field (RMF) framework, distinguishing it from traditional quantum hadrodynamics (QHD), which treats nucleons as point-like particles. In this work, we implement the QMC model within the DaeJeon Boltzmann-Uehling-Uhlenbeck (DJBUU) transport code to investigate its applicability to intermediate-energy heavy-ion collisions. We simulate \textsuperscript{197}Au+\textsuperscript{197}Au collisions at a beam energy of 400 A MeV using both QHD and QMC and find that both approaches yield comparable results for bulk observables such as transverse and directed flow, with good agreement with experimental data. To further assess the model performance, we study pion production in neutron-rich (\textsuperscript{132}Sn+\textsuperscript{124}Sn) and less neutron-rich (\textsuperscript{108}Sn+\textsuperscript{112}Sn) systems at 270 A MeV. In contrast to the QHD case, reproducing the observed pion yields and charge ratios within the QMC framework requires a slightly reduced density-dependent suppression in the in-medium $\Delta$ production cross-section. These results demonstrate that the QMC model can be effectively integrated into transport simulations.