# An estimate of higher twist at small x and low Q^2 based upon a saturation model

Source: [An estimate of higher twist at small x and low Q^2 based upon a saturation model](<https://www.sota2.com/research/paper/68fa22977a2b558e2933c9a1>)

Collection index: [llms.txt](<https://www.sota2.com/research/llms.txt>)

Data updated: 2025-10-24T05:01:57.088Z

Authors: J. Bartels, K.Golec-Biernat, K. Peters

Published: 2000-03-06T16:40:33.000Z

## Abstract

We investigate the influence of higher twist corrections to deep inelastic structure functions in the low-$Q^2$ and small-$x$ HERA region. We review the general features of the lowest-order QCD diagrams which contribute to twist-4 at small-$x$, in particular the sign structure of longitudinal and transverse structure functions which offers the possibility of strong cancellations in $F\_2$. For a numerical analysis we perform a twist analysis of the saturation model which has been very successful both in describing the structure function and the DIS diffractive cross section at HERA. As the main conclusion, twist 4 corrections are not small in $F\_L$ or $F\_T$ but in $F\_2=F\_L + F\_T$ they almost cancel. This indicates the limitation on the use of the DGLAP formalism at small $x$ and $Q^2$. We point out that $F\_L$ analysis needs a large twist-4 correction. We also indicate the region of validity of the twist expansion.

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## Original sources and implementation

[Original paper](<https://arxiv.org/abs/hep-ph/0003042>)

[PDF](<https://arxiv.org/pdf/hep-ph/0003042.pdf>)