Energy, centrality and momentum dependence of dielectron production at collider energies in a coarse-grained transport approach

TL;DR

This study uses coarse-grained transport simulations to analyze dielectron production in heavy-ion collisions at RHIC and LHC energies, showing good agreement with experimental data and providing predictions for future measurements.

Contribution

It introduces a novel approach combining transport models with in-medium spectral functions to accurately describe dilepton spectra across collider energies.

Findings

Good agreement with RHIC dilepton spectra

Consistent low-mass spectra with hadronic and QGP contributions

Predictions indicate increased thermal contribution at LHC energies

Abstract

Dilepton production in heavy-ion collisions at collider energies - i.e., for the Relativistic Heavy-Ion Collider (RHIC) and the Large Hadron Collider (LHC) - is studied within an approach that uses coarse-grained transport simulations to calculate thermal dilepton emission applying in-medium spectral functions from hadronic many-body theory and partonic production rates based on lattice calculations. The 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 resulting dilepton spectra are in good agreement with the experimental results for the range of RHIC energies, $\sqrt{s_{NN}}=19.6 - 200$ GeV. The comparison of data and model outcome shows that the newest measurements by the PHENIX and STAR collaborations are consistent and that the low-mass spectra can be described by a cocktail of hadronic decay contributions together with thermal emission from broadened vector-meson spectral functions and from the Quark-Gluon Plasma phase. Predictions for dilepton results at LHC energies show no significant change of the spectra as compared to RHIC, but a higher fraction of thermal contribution and harder slopes of the transverse momentum distributions due to the higher temperatures and flow obtained.