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

Abstract: The electric conductivity, $\sigma_{\rm el}$, 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 $\sigma_{\rm el}$. In particular, we disentangle the contributions from QGP and hadronic emission, and identify signatures that can help to extract $\sigma_{\rm el}$ from high-precision experimental data expected to be attainable with future detector systems at the LHC.