Probing the QCD phase diagram with dileptons - a study using coarse-grained transport dynamics

TL;DR

This paper investigates dilepton production in heavy-ion collisions using coarse-grained transport simulations to explore the QCD phase diagram, linking experimental spectra to the fireball's evolution in temperature and chemical potential.

Contribution

It introduces a novel approach combining UrQMD simulations with in-medium spectral functions to probe the QCD phase diagram through dilepton spectra.

Findings

Dilepton excess correlates with the fireball's trajectory in the T-μB plane.

The method successfully reproduces experimental dilepton spectra.

Insights into the QCD phase transition are gained from the spectral analysis.

Abstract

Dilepton production in heavy-ion collisions at various energies is studied using coarse-grained transport simulations. Microscopic output from the Ultra-relativistic Quantum Molecular Dynamics (UrQMD) model is hereby put on a grid of space-time cells which allows to extract the local temperature and chemical potential in each cell via an equation of state. The dilepton emission is then calculated applying in-medium spectral functions from hadronic many-body theory and partonic production rates based on lattice calculations. The comparison of the resulting spectra with experimental data shows that the dilepton excess beyond the decay contributions from a hadronic cocktail reflects the trajectory of the fireball in the $T-\mu_{\mathrm{B}}$ plane of the QCD phase diagram.