Nonperturbative estimate of the heavy quark momentum diffusion coefficient

We estimate the momentum diffusion coefficient of a heavy quark within a pure SU(3) plasma at a temperature of about 1.5T sub(c). Large-scale Monte Carlo simulations on a series of lattices extending up to 192 super(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 super(3). This implies that the "drag coefficient," characterizing the time scale at which heavy quarks adjust to hydrodynamic flow, is (ProQuest: Formulae and/or non-USASCII text omitted) = (1.8-3.4)(T sub(c)/T) super(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.