PUB - Publikationen an der Universität Bielefeld

We estimate the momentum diffusion coefficient of a heavy quark within a pure SU(3) plasma at a temperature of about 1.5Tc. Large-scale Monte Carlo simulations on a series of lattices extending up to 192(3) x 48 permit us to carry out a continuum extrapolation of the so-called color-electric imaginary-time correlator. The extrapolated correlator is analyzed with the help of theoretically motivated models for the corresponding spectral function. Evidence for a nonzero transport coefficient is found and, incorporating systematic uncertainties reflecting model assumptions, we obtain kappa = (1.8- 3.4)T-3. This implies that the "drag coefficient," characterizing the time scale at which heavy quarks adjust to hydrodynamic flow, is eta(-1)(D) eta(-1)(D) = (1.8-3.4) (T-c/T)(2) (M/1.5 GeV) fm/c, where M is the heavy quark kinetic mass. The results apply to bottom and, with somewhat larger systematic uncertainties, to charm quarks.