Electric Conductivity of QCD Matter and Dilepton Spectra in Heavy-Ion Collisions

Abstract

The electric conductivity, ${\sigma }_{\mathrm{el}}$, is a fundamental transport coefficient of QCD matter that can be related to the zero-energy limit of the electromagnetic (EM) spectral function at vanishing 3-momentum in the medium. The EM spectral function is also the central quantity to describe the thermal emission rates and pertinent spectra of photon and dilepton radiation in heavy-ion collisions. Employing a model for dilepton rates that combines hadronic many-body theory with nonperturbative QGP emission constrained by lattice-QCD which describes existing dilepton measurements in heavy-ion collisions, we investigate the sensitivity of low-mass dilepton spectra in Pb-Pb collisions at the LHC to ${\sigma }_{\mathrm{el}}$. In particular, we disentangle the contributions from QGP and hadronic emission, and identify signatures that can help to extract ${\sigma }_{\mathrm{el}}$ from high-precision experimental data expected to be attainable with future detector systems at the LHC.

Comments: 7 pages, 11 figures