Nuclear Dependence in Drell-Yan Transverse Momentum Distribution

We calculate the nuclear enhancement in Drell-Yan transverse momentum distribution in hadron-nucleus collisions. In terms of multiple scattering picture, we compute the contributions from double scattering. Applying the generalized factorization theorem, we express the nuclear enhancement in terms of twist-4 nuclear parton correlation functions. We demonstrate that these twist-4 nuclear parton correlation functions are universal, and are the same as those used to explain the nuclear dependence in di-jet momentum imbalance and in direct photon production. Using the known information on the twist-4 parton correlation functions, we estimate the nuclear enhancement for Drell-Yan pair in large $q_T$ region. We also discuss the source of nuclear suppression in small $q_T$ region.