MEASUREMENTS OF ELASTIC ELECTRON SCATTERING FROM THE PROTON AT HIGH MOMENTUM TRANSFER

Absolute measurements of the differential cross section for elastic electron-proton scattering were made in the range of momentum transfer from Q('2) = 2.9 to 31.3 (GeV/c)('2) using an electron beam at the Stanford Linear Accelerator Center. The data span six orders of magnitude in cross section. Combined statistical and systematic uncertainties in the cross section measurements ranged from 3% at low Q('2) to 19% at high Q('2). These data have been used to extract values of either the proton magnetic form factor G(,M)('p)(Q('2)) or Dirac form factor F(,1)('p)(Q('2)) under the assumption that the electric form factor G(,E)('p)(Q('2)) follows the scaling relation G(,E)('p)(Q('2)) = G(,M)('p)(Q('2))/(mu)(,p). The results at high momentum transfer are in rough agreement with the logarithmic falloff of Q('4)F(,1)('p) expected from leading twist predictions of perturbative quantum chromodynamics (QCD). An improved treatment is given for evaluating the argument of the running strong coupling constant (alpha)(,s)(Q('2)) in each QCD diagram, resulting in improved agreement of the leading twist predictions with the data at high Q('2).