  Charm- and bottom-quark rescattering in a Quark-Gluon Plasma (QGP) is
investigated with the objective of assessing the approach towards
thermalization. Employing a Fokker-Planck equation to approximate the collision
integral of the Boltzmann equation we augment earlier studies based on
perturbative parton cross sections by introducing resonant heavy-light quark
interactions. The latter are motivated by recent QCD lattice calculations which
indicate the presence of "hadronic" states in the QGP. We model these states by
colorless (pseudo-) scalar and (axial-) vector D- and B-mesons within a
heavy-quark effective theory framework. We find that the presence of these
states at moderate QGP temperatures substantially accelerates the kinetic
equilibration of c-quarks as compared to using perturbative interactions. We
also comment on consequences for $D$-meson observables in ultra-relativistic
heavy-ion collisions.
