Towards a non-perturbative measurement of the heavy quark momentum diffusion coefficient

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We report on a lattice investigation of heavy quark diffusion within pure SU(3) plasma above the deconfinement transition, with the quarks treated to leading order in the heavy mass expansion. Using a multilevel algorithm, several volumes and lattice spacings, as well as tree-level improvement and perturbative renormalization, we measure the relevant "colour-electric" Euclidean correlator, finding that it clearly exceeds its perturbative counterpart. Even without analytic continuation, this suggests that at temperatures just above the critical one, non-perturbative interactions felt by the heavy quarks are stronger than within the weak-coupling expansion. After introducing rough modelling of the spectral shape, diffusion coefficients down to D 0.5/T appear possible.