Leading-order perturbative QCD calculation of nucleon Dirac form factors.

Abstract

The Dirac form factors ${F}_{1}^{p}$,n of nucleons are analyzed to leading order in the strong coupling constant ${\ensuremath{\alpha}}_{s}$(${Q}^{2}$) and leading twist using perturbative QCD. The effects of different choices of the nucleon distribution amplitude on the leading-twist result are explored. These results are compared with recent experimental data for the proton. We show that it is possible to fit the data for ${F}_{1}^{p}$ in the range 10\ensuremath{\le}${Q}^{2}$\ensuremath{\le}30 (GeV/c${)}^{2}$ by evaluating the strong coupling constant ${\ensuremath{\alpha}}_{s}$(${Q}^{2}$) at the exact gluon kinematics for each diagram of the process within the integrals over the momentum fraction which govern the perturbative QCD prediction.