title: Lattice study of the jet quenching parameter.
abstract: We present a first-principle computation of the jet quenching parameter, which describes the momentum broadening of a high-energy parton moving through the deconfined state of QCD matter at high temperature. Following an idea originally proposed by Caron-Huot, we explain how one can evaluate the soft contribution to the collision kernel characterizing this real-time phenomenon, analyzing certain gauge-invariant operators in a dimensionally reduced effective theory (electrostatic QCD), which can be studied nonperturbatively via simulations on a Euclidean lattice. Our high-precision numerical computations at two different temperatures indicate that soft contributions to the jet quenching parameter are large. After discussing the systematic uncertainties involved, we present a quantitative estimate for the jet quenching parameter in the temperature range accessible at heavy-ion colliders, and compare it to results from phenomenological models as well as to strong-coupling computations based on the holographic correspondence.
authors.affiliation: Instituto de Física Téorica UAM/CSIC, Universidad Autónoma de Madrid, E-28049 Madrid, Spain and Department of Physics and Helsinki Institute of Physics, University of Helsinki, P.O. Box 64, FI-00014, Finland.
authors.forename: Marco
authors.initials: M
authors.lastname: Panero
authors.affiliation: Department of Physics and Helsinki Institute of Physics, University of Helsinki, P.O. Box 64, FI-00014, Finland.
authors.forename: Kari
authors.initials: K
authors.lastname: Rummukainen
authors.affiliation: Institute for Theoretical Physics, University of Regensburg, D-93040 Regensburg, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Schäfer