Do Sum Rules in Deep Inelastic Scattering Follow From QCD?
  We consider restrictions imposed on the electromagnetic and weak current operators by Poincare invariance and show that some assumptions used in deriving the sum rules in deep inelastic scattering (DIS) have no physical ground. In particular there is no ground to neglect the contribution of nonperturbative effects to these operators, even in the Bjorken limit. Therefore the conclusion that the sum rules in DIS unambiguously follow from QCD is not substantiated. 
Felix M. Lev