Parton energy loss in high energy hard forward processes in proton-nucleus collisions

We calculate the spectrum of energy loss differences due to gluon radiation in high energy hard forward processes in proton-nucleus collisions as compared to proton-proton collisions. We find that the nuclear induced energy loss scales linearly with the beam energy. We evaluate the spectrum and “typical” energy losses in a logarithmic and large $N_c$ approximation. The energy losses found appear large enough to be phenomenologically important.