Many body QCD effects in proton-nucleus collisions at RHIC

The proton-nucleus (p+A) collision program at the Relativistic Heavy Ion Collider (RHIC) plays an important complementary role to the search for the quark-gluon plasma in the most central nucleus-nucleus (A+A) collisions. Since no phase transition to the deconfined state of QCD is expected, such reactions can be very useful in quantifying the many body QCD dynamics in cold nuclear matter. I will briefly review the derivation of three important partonic effects: the diffusion of quarks and gluons in transverse momentum space, their initial state radiative energy loss and the suppression of jet and dijet rates from their coherent final state scattering. I will show first results from a perturbative QCD calculation which attempts to systematically incorporate all of these effects. Our approach can naturally be extended to study interactions of heavy quarks in nuclei.