Energy loss at largexFin nuclear collisions

Measurements of the Drell-Yan process and of charmonium and bottomonium production at CERN and Fermilab show a depletion at high Feynman x in large relative to small nuclear targets. We can attribute this depletion to energy loss of initial and final states, provided that the loss is (dE/dz${)}_{\mathrm{Drell}\mathrm{-}\mathrm{Yan}}$=4/9 (dE/dz${)}_{\mathrm{charm}}$∼1.5 GeV/fm at the highest ${\mathit{x}}_{\mathit{F}}$ measured. This small loss is magnified in the differential cross section due to the strong behavior ∼(1-x${)}^{\mathit{n}}$ of the projectile’s structure functions at large x.