The Longitudinal Structure Function at HERA

TL;DR

This paper evaluates different theoretical models for the longitudinal structure function in deep inelastic scattering, comparing their predictions to recent HERA data to identify which approaches best match observations.

Contribution

It provides a comprehensive comparison of fixed-order QCD, higher twist, small-x resummations, and dipole models against experimental data, highlighting their respective uncertainties.

Findings

Different models show varying degrees of agreement with HERA data.

Data to be analyzed further could discriminate between theoretical approaches.

Theoretical uncertainties impact the interpretation of the longitudinal structure function.

Abstract

I investigate the theoretical uncertainties on the predictions for the longitudinal structure function. I compare the predictions using fixed-order perturbative QCD, higher twist corrections, small-x resummations and the dipole picture. I compare the various predictions to the recent HERA measurements and examine how the data still to be analysed may discriminate between the approaches.