Electromagnetic probes of the quark‐gluon plasma

Abstract

In this paper, we investigate dilepton production in heavy-ion collisions from √ s NN = 8 to 200 GeV with a focus on the competition between the thermal quark-gluon plasma (QGP) radiation and the semi-leptonic decays from correlated D-meson pairs. As a "tool," we employ the parton-hadron string dynamics (PHSD) transport approach incorporating a fully microscopic treatment of the charm dynamics and their semi-leptonic decays. We find that the dileptons from correlated D-meson decays dominate the "thermal" radiation from the QGP in central Pb + Pb collisions at the intermediate masses (1.2 GeV < M < 3 GeV) for √ s NN > 40 GeV, while for √ s NN = 5−20 GeV, the contribution from D, D decays to the intermediate mass dilepton spectra is subleading such that one should observe a rather clear signal from the QGP radiation, which is dominated by the annihilation channel qq → * . KEYWORDSheavy ions -quark-gluon plasma -transport models 1