Dilepton production by dynamical quasi-particles in the strongly interacting quark–gluon plasma

Abstract

The dilepton production by the constituents of the strongly interacting quark-gluon-plasma (sQGP) is addressed. In order to make quantitative predictions at realistically low plasma temperatures (O(Tc)), experimentally relevant low dilepton mass (O(1 GeV)) and strong coupling (αS ∼ 0.5 ÷ 1), we take into account not only the higher order pQCD reaction mechanisms, but also the non-perturbative spectral functions and self-energies of the quarks, anti-quarks and gluons thus going beyond the leading twist. For this purpose, our calculations utilize parametrizations of the non-perturbative propagators for quarks and gluons provided by the dynamical quasi-particle model (DQPM) matched to reproduce lattice data. The DQPM describes QCD properties in terms of single-particle Green's functions (in the sense of a two-particle irreducible approach) and leads to the notion of the constituents of the sQGP being effective quasiparticles, which are massive and have broad spectral functions (due to large interaction rates). In the present work, we derive the off-shell cross sections of dilepton production in the reactions q +q → l + l − (Drell-Yan mechanism), q +q → g + l + l − (quark annihilation with the gluon Bremsstrahlung in the final state),(virtual gluon decay, virtual quark decay) in the sQGP by dressing the quark and gluon lines in the perturbative diagrams with the DQPM propagators for quarks and gluons.

Dilepton production in nucleus-nucleus collisions at top CERN Super Proton Synchrotron energy of 158AGeV within the parton-hadron-string dynamics transport approach

“…3 and 4 of Ref. [36]). The modifications are large at lower M 2 and at the edges of the phase space.…”

“…[36]. It was shown that the finite quark and gluon masses can modify the magnitude as well as the M − and p T −dependence of the cross sections of the processes in Fig.…”

“…[36] by convoluting the off-shell cross sections with phenomenological spectral functions A(m q ) and A(m g ) for the quarks and gluons in the quark-gluon plasma and with parton distributions in a heavy-ion collision similar to those of Fig. 2 in the present paper.…”

Dilepton production in proton-proton and Pb+Pb collisions atsNN=2.76TeV

“…Accordingly, we have calculated in Refs. [26,27] the off-shell cross sections for dilepton production in the partonic channels by offshell partons, using the phenomenological parametrizations from the DQPM for the quark and gluon propagators and their interaction strength.…”

Analysis of dilepton production inAu+Aucollisions atsNN=200GeV within the parto

“…Accordingly, we have calculated in Refs. [33,34] the off-shell cross sections for dilepton production in the partonic channels by off-shell partons, using the phenomenological parametrizations (from the DQPM) for the quark and gluon propagators and their interaction strength.…”