  We use an s-channel picture of hard hadronic collisions to investigate the
parton distribution function for quarks at small momentum fraction x, which
corresponds to very high energy scattering. We study the renormalized quark
distribution at one loop in this approach.
  In the high-energy picture, the quark distribution function is expressed in
terms of a Wilson-line correlator that represents the cross section for a color
dipole to scatter from the proton. We model this Wilson-line correlator in a
saturation model. We relate this representation of the quark distribution
function to the corresponding representation of the structure function
F_T(x,Q^2) for deeply inelastic scattering.
