  We consider momentum broadening and energy loss of high momentum partons in a
hot non-Abelian plasma due to collisions. We solve the coupled system of
Wong-Yang-Mills equations on a lattice in real time, including binary hard
elastic collisions among the partons. The collision kernel is constructed such
that the total collisional energy loss and momentum broadening are lattice
spacing independent. We find that the transport coefficient $\hat{q}$
corresponding to transverse momentum broadening receives sizable contributions
from a power-law tail in the $p_\perp$-distribution of high-momentum partons.
We establish the scaling of $\hat{q}$ and of $dE/dx$ with density, temperature
and energy in the weak-coupling regime. We also estimate the nuclear
modification factor $R_{AA}$ due to elastic energy loss of a jet in a classical
Yang-Mills field.
