Nucleon structure as a background for determination of fundamental parameters

We consider deep inelastic (quasi)elastic lepton-nucleon scattering and investigate the possibilities of eliminating or suppressing theoretical uncertainties induced by the nucleon structure in measuring the standard model parameters or in searching for new physics. On the basis of rather general assumptions about nucleon structure we have obtained new relations between cross sections and neutral current parameters which are weakly dependent on the nucleon structure. We also investigate the dependence of the QCD $\Lambda$ parameter extracted from the data on the unknown large-scale nucleon structure and propose a modification of the conventional QCD predictions in which the dependence on this uncertainty factor is suppressed.