Evidence for breakdown of the DGLAP description in diffractive DIS at HERA

TL;DR

This paper presents evidence that the DGLAP framework fails to accurately describe low-Q^2 diffractive DIS data at HERA, indicating significant higher-twist effects and impacting predictions for the LHC.

Contribution

It provides the first direct evidence of higher-twist effects in DIS, challenging the validity of the DGLAP description at low Q^2 in diffractive processes.

Findings

Deviations from DGLAP predictions below Q^2~5 GeV^2

Deviations up to 100% at low pomeron ξ

Consistent with higher twists from saturation models

Abstract

HERA data on diffractive DIS show deviations from twist 2 DGLAP predictions below $Q^2\sim 5$ GeV$^2$ at low pomeron $\xi$, which may reach up to 100%. These deviations are consistent with higher twists effects extracted from the saturation model. It is a first direct evidence for the higher twists in DIS. This finding affects determination of the diffractive parton densities that are used for the predictions at the LHC.