  Yields, correlation shapes, and mean transverse momenta \pt{} of charged
particles associated with intermediate to high-\pt{} trigger particles ($2.5 <
\pt < 10$ \GeVc) in d+Au and Au+Au collisions at $\snn=200$ GeV are presented.
For associated particles at higher $\pt \gtrsim 2.5$ \GeVc, narrow correlation
peaks are seen in d+Au and Au+Au, indicating that the main production mechanism
is jet fragmentation. At lower associated particle $\pt < 2$ \GeVc, a large
enhancement of the near- ($\dphi \sim 0$) and away-side ($\dphi \sim \pi$)
associated yields is found, together with a strong broadening of the away-side
azimuthal distributions in Au+Au collisions compared to d+Au measurements,
suggesting that other particle production mechanisms play a role. This is
further supported by the observed significant softening of the away-side
associated particle yield distribution at $\dphi \sim \pi$ in central Au+Au
collisions.
