  Heavy quark drag coefficients in the quark-gluon plasma are evaluated in the
perturbative QCD. It is found that for charm quarks the contribution from
three-body elastic scattering is comparable to those from two-body elastic and
radiative scatterings while for bottom quarks it becomes dominant. Using a
schematic expanding fireball model, effects of both two-body and three-body
scatterings on the transverse momentum spectra of heavy quarks produced in
Au+Au collisions at center of mass energy $\sqrt{s_{NN}}=200$ GeV are studied.
Results on electrons from resulting heavy meson decays are compared with
available experimental data.
