Simple description of electroproduction and muoproduction in asymptotically free gauge theories

We propose a simple model for the structure functions characterizing deep-inelastic leptoproduction off nucleons. Our approach adapts the quark-parton model to include scaling violations predicted in asymptotically free gauge theories. With the normalization of νW2 fixed by data at essentially two values of Q2, we are able to predict νW2 over the remaining, large experimental range. The agreement with the data is good even down to quite low values of Q2 (Q2≃1 GeV2). Given our model for νW2 and a model for FL, we obtain unique predictions for 2MW1 and hence for R=σLσT. The agreement of the former with experiment is as good as in the case of νW2. The predictions for R while still somewhat low at small x are substantially better, especially at high x, than those deduced previously in approaches based on asymptotically free gauge theories.