Modeling Lepton-Nucleon Inelastic Scattering from High to Low Momentum Transfer

We present a model for inclusive charged lepton-nucleon and (anti)neutrino-nucleon cross sections at momentum transfer squared, Q2, ~1 GeV2. We quantify the impact of existing low-Q charged-lepton deep-inelastic scattering (DIS) data on effects due to high-twist operators and on the extraction of parton distribution functions (PDFs). No evidence is found for twist-6 contributions to structure functions (SF), and for a twist-4 term in the longitudinal SF at x' > ~'0.1. We find that DIS data are consistent with the NNLO QCD approximation with the target mass and phenomenological high twist corrections. For Q2 < 1 GeV2, we extend extrapolation of the operator product expansion, preserving the low-Q current-conservation theorems. The procedure yields a good description of data down to Q2~0.5 GeV2. An updated set of PDFs with reduced uncertainty and applicable down to small momentum transfers in the lepton-nucleon scattering is obtained.