Twist expansion of forward Drell-Yan process

Abstract

We present a twist expansion of differential cross-sections of the forward Drell-Yan process at the high energies. The expansion of all invariant form-factors is performed assuming GBW saturation model and the saturation scale plays the role of the hadronic scale of OPE. Some expilicit predictions for LHC experiments are given. It is shown also how the Lam-Tung relation is broken at twist 4 what provides a sensitive probe for searching of higher twists.