Hadronic structure of the photon at small x in holographic QCD

TL;DR

This paper investigates the hadronic structure of the photon at small x using holographic QCD, modeling the photon as a hadron via vector meson fluctuations and Pomeron exchange, with results aligning with experimental data.

Contribution

The study introduces a holographic QCD approach to compute photon structure functions at small x, incorporating vector meson fluctuations and Pomeron exchange, providing new theoretical predictions.

Findings

Agreement with OPAL experimental data

Consistency with existing photon parton distribution functions

Predictions for future collider experiments

Abstract

We present our analysis on the photon structure functions at small Bjorken variable x in the framework of the holographic QCD. In the kinematic region, a photon can fluctuate into vector mesons and behaves like a hadron rather than a pointlike particle. Assuming the Pomeron exchange dominance, the dominant hadronic contribution to the structure functions is computed by convoluting the probe and target photon density distributions obtained from the wave functions of the U(1) vector field in the five-dimensional AdS space and the Brower-Polchinski-Strassler-Tan Pomeron exchange kernel. Our calculations are in agreement with both the experimental data from OPAL collaboration at LEP and those calculated from the parton distribution functions of the photon proposed by Gl\"uck, Reya, and Schienbein. The predictions presented here will be tested at future linear colliders, such as the planned International Linear Collider.