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

TL;DR

This paper develops a model for lepton-nucleon scattering at low to moderate momentum transfer, analyzing the impact of low-Q data on parton distribution functions and high-twist effects, and extending the operator product expansion to lower Q^2.

Contribution

It introduces a comprehensive model that accurately describes scattering data down to Q^2 ~ 0.5 GeV^2 and provides an updated set of PDFs with reduced uncertainties for low momentum transfer.

Findings

No evidence for twist-6 contributions to structure functions.

DIS data align with NNLO QCD with target mass and high-twist corrections.

Extended operator product expansion describes data down to Q^2 ~ 0.5 GeV^2.

Abstract

We present a model for inclusive charged lepton-nucleon and (anti)neutrino-nucleon cross sections at momentum transfer squared, $Q^2$, $\sim1 {\rm GeV}^2$. 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 logitudinal SF at $x\gtrsim0.1$. We find that DIS data are consistent with the NNLO QCD approximation with the target mass and phenomenological high twist corrections. For $Q^2<1 {\rm GeV}^2$, 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 $Q^2\sim 0.5 {\rm GeV}^2$. An updated set of PDFs with reduced uncertainty and applicable down to small momentum transfers in the lepton-nucleon scattering is obtained.