Higher twists in deep inelastic scattering
  We perform an exploratory study of higher twist contributions to deep inelastic scattering. We estimate the size of two major sources of higher twist, namely absorptive corrections and the vector meson dominance (VMD) contribution. We find that they give a sizeable higher twist component of F_2. For example at x = 0.01 it is about 8% (17%) at Q^2 = 10 GeV^2 (4 GeV^2), reaching up to 27% at x = 10^{-4} and Q^2 = 4 GeV^2. At the smaller x value the largest contribution comes from absorptive corrections, while at the larger values of x the VMD term dominates. 
A. D. Martin, M. G. Ryskin