Twist expansion of the nucleon structure functions, F2 and FL, in the DGLAP improved saturation model

TL;DR

This paper investigates higher twist effects in nucleon structure functions F2 and FL at small x using a saturation model fitted to HERA data, revealing significant corrections for FL and cancellations in F2.

Contribution

It provides a twist analysis within a DGLAP improved saturation model, offering new insights into higher twist effects on structure functions at small x.

Findings

Higher twist corrections are sizable for FL.

Nearly complete cancellation of twist-4 corrections in F2.

Predictions for future LHC measurements.

Abstract

Higher twist effects in the deeply inelastic scattering are studied. We start with a short review of the theoretical results on higher twists in QCD. Within the saturation model we perform a twist analysis of the nucleon structure functions FT and FL at small value of the Bjorken variable x. The parameters of the model are fitted to the HERA F2 data, and we derive a prediction for the longitudinal structure function FL. We conclude that for FL the higher twist corrections are sizable whereas for F2 = FT + FL there is a nearly complete cancellation of twist-4 corrections in FT and FL. We discuss a few consequences for future LHC measurements.