Nuclear Enhanced Higher-Twist Effects in the Drell-Yan Process
  We calculate the Drell-Yan cross section, resolving the full kinematics of the lepton pair, at high transverse momentum for hadron nucleus collisions. We use the general framework of Luo, Qiu and Sterman to calculate double scattering contributions that are of twist-4 and demonstrate their nuclear enhancement. By comparing single and double scattering at RHIC energies we find that double scattering gives contributions of comparable size. We also show that the angular dependence of the Drell-Yan pair discriminates between the various double scattering contributions. 
R.J. Fries, A. Sch\"afer, E. Stein, B. M\"uller