Marco Panero, Kari Rummukainen, Andreas Schäfer
We present a first-principle computation of the jet quenching parameter that 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 non-perturbatively 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 collision facilities, and compare it to experimental results as well as to theoretical strong-coupling computations based on the holographic correspondence.
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http://arxiv.org/abs/1307.5850
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