Precise extractions of the x and Q2 dependence of R = σL/σT, F2p, F2d, and F2n/2p from a combined analysis of SLAC [Stanford Linear Accelerator Center] deep inelastic electron scattering experiments

We report on a precise study of the x and Q2 dependence of the proton, deuteron and neutron structure functions. In particular R = σL/σT, F2p, F2d, and the ratio F2d/F2p were extracted in a combined analysis of SLAC deep inelastic electron scattering experiments. Data from eight experiments were radiatively corrected with a new improved radiative correction formalism, and all experiments were normalized to the precise data of SLAC E140, thus yielding a single coherent data set. We find that Rp = Rd as expected from QCD. The results for R are somewhat larger than the prediction of QCD with target mass effects, thus indicating the existence of additional dynamic higher twist effects. Using both SLAC and CERN data, we obtained a parametrization of R in the range 0.5< Q2 <200 GeV/c2 and 0.1 < x < 0.86. This fit in conjunction with the normalized hydrogen and deuterium cross sections was used to extract precise values of F2. These data provide a constraint at low Q2 for high Q2 muon and neutrino experiments. A study of the Q2 dependence of the ratio of deuteron and proton structure functions shows a slope which is consistent with QCD and explains the difference in this ratio between SLAC and CERN experiments. 7 figs