  The cross section for Drell-Yan pair production in the limit of small
$x$-target is derived in the rest frame of the target hadron. Our calculation
is based on the fundamental quantity $\sigma(\rho)$, the cross section for the
scattering of a $q\bar{q}$-pair with fixed transverse separation $\rho$ off a
hadronic target. As in deep inelastic scattering the result can be given in
terms of integrals of $\sigma(\rho)$. This is consistent with well known
factorization theorems and also relates higher-twist terms in both processes.
An analysis of the angular distribution of the produced lepton shows that
additional integrals of $\sigma(\rho)$ can be obtained in the Drell-Yan
process, which are not measurable in inclusive deep inelastic scattering.

High Energy Physics - Phenomenology