Extraction of gluon distributions from structure functions at small x in holographic QCD

TL;DR

This paper uses holographic QCD to extract gluon distribution functions in nucleons and pions at small x, showing consistency with global analyses and predicting pion gluon densities without extra parameters.

Contribution

It introduces a holographic QCD approach to determine gluon distributions from structure functions, including predictions for pions without additional parameters.

Findings

Proton gluon distribution aligns with recent global QCD results.

Pion gluon density is smaller than proton's and agrees with global analyses.

Model parameters are fixed using HERA data.

Abstract

We investigate the nucleon and pion gluon distribution functions in the framework of holographic QCD, focusing on the small Bjorken x region. Based on an approximate relation, the gluon distributions are extracted from structure functions of the unpolarized deep inelastic scattering which can be calculated with a holographic QCD model, assuming the Pomeron exchange. All the adjustable parameters of the model are determined with the HERA data of the proton structure functions. We explicitly show that the extracted proton gluon distribution is consistent with results of the recent global QCD analysis. The structure functions of the pion can be computed without any additional parameter, which enables us to predict its gluon distribution also. We find that the resulting pion gluon density is smaller than the proton's, and agrees with the recent global QCD analysis result within the uncertainties.