title: Transport coefficients in Yang-Mills theory and QCD.
abstract: We calculate the shear-viscosity-over-entropy-density ratio η/s in Yang-Mills theory from the Kubo formula using an exact diagrammatic representation in terms of full propagators and vertices using gluon spectral functions as external input. We provide an analytic fit formula for the temperature dependence of η/s over the whole temperature range from a glueball resonance gas at low temperatures, to a high-temperature regime consistent with perturbative results. Subsequently, we provide a first estimate for η/s in QCD.
authors.affiliation: Institut für Theoretische Physik, Universität Heidelberg, Philosophenweg 16, 69120 Heidelberg, Germany.
authors.forename: Nicolai
authors.initials: N
authors.lastname: Christiansen
authors.affiliation: Institut für Theoretische Physik, Universität Heidelberg, Philosophenweg 16, 69120 Heidelberg, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Haas
authors.affiliation: Institut für Theoretische Physik, Universität Heidelberg, Philosophenweg 16, 69120 Heidelberg, Germany.|ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung mbH, Planckstrasse 1, 64291 Darmstadt, Germany.
authors.forename: Jan M
authors.initials: JM
authors.lastname: Pawlowski
authors.affiliation: Institut für Theoretische Physik, Universität Heidelberg, Philosophenweg 16, 69120 Heidelberg, Germany.
authors.forename: Nils
authors.initials: N
authors.lastname: Strodthoff