Comparison of heavy ion transport simulations: Ag+Ag collisions at Elab = 1.58 AGeV

TL;DR

This study compares several microscopic transport models predicting hadron production and spectra in Ag+Ag collisions at 1.58 AGeV, finding consistent multiplicities and source temperatures despite differences in model implementations.

Contribution

It provides a systematic comparison of transport models for heavy ion collisions at low energies, highlighting their similarities and differences in particle production predictions.

Findings

Models show consistent hadron multiplicities.

Source temperatures are similar across models (~80-95 MeV).

Substantial radial flow is observed in all models.

Abstract

We compare the microscopic transport models UrQMD, PHSD, PHQMD, and SMASH to make predictions for the upcoming Ag+Ag data at $E_\mathrm{lab}=1.58$~$A$GeV ($\sqrt{s_\mathrm{NN}}=2.55$~GeV) by the HADES collaboration. We study multiplicities, spectra and effective source temperatures of protons, $\pi^{\pm,0}$, $K^\pm$, the $\eta$, $\Lambda+\Sigma^0$ and the $\Xi^-$ within these models. Despite variations in the detailed implementation of the dynamics in the different models, the employed transport approaches all show consistent multiplicities of the bulk of investigated hadrons. The main differences are in the $\Xi^-$ production, which is treated differently between UrQMD/SMASH on one side employing high mass resonance states with explicit decays to $\mathrm{Resonance}\rightarrow \Xi+K+K$ in contrast to PHSD/PHQMD which account only non-resonant $\Xi$ production channels. A comparison of the spectra, summarized by effective source temperatures, shows that all models provide similar source temperatures around $T_\mathrm{source}=80-95$~MeV, and show substantial radial flow on the order of $\langle v_T\rangle=0.22c-0.3c$ even for such a small system.