Dilepton production in the strongly interacting quark-gluon plasma

TL;DR

This paper models dilepton production in heavy-ion collisions using a microscopic transport approach, successfully reproducing certain experimental spectra by including both hadronic and partonic sources, and highlighting the importance of medium effects.

Contribution

It introduces a detailed microscopic model that combines hadronic and partonic sources to accurately describe dilepton spectra in heavy-ion collisions.

Findings

The model reproduces the NA60 data well with collisional broadening and off-shell quark-antiquark annihilation.

The model explains the softening of mT spectra at intermediate masses.

The model underestimates the PHENIX data for 0.2-0.6 GeV mass range.

Abstract

Dilepton production in relativistic heavy-ion collisions is studied within the microscopic Parton-Hadron-String Dynamics (PHSD) transport approach, which is based on a dynamical quasiparticle model (DQPM) matched to reproduce lattice QCD results in thermodynamic equilibrium. A comparison to the data of the NA60 Collaboration for In+In collisions at 158 AGeV shows that the dilepton spectra are well described by the sum of hadronic and partonic sources, if a collisional broadening of vector mesons is taken into account as well as the off-shell quark-antiquark annihilation (q+qbar->l^+l^- and q+qbar->gl^+l^-) in the QGP. In particular, the observed softening of the mT spectra at intermediate masses is reproduced. The data of the PHENIX collaboration on dilepton production in Au+Au collisions at sqrt(s)=200 GeV for masses above 1 GeV are found to be dominated by the contributions of the QGP radiation and the charm meson decays, while the measured spectrum is underestimated in the mass range from 0.2 to 0.6 GeV.