Comparing AdS/CFT Calculations to HERA F_2 Data

TL;DR

This paper demonstrates that an AdS/CFT-inspired color-dipole model with minimal parameters can effectively describe HERA F_2 data at small x, predicting energy-independent saturation scales and structure functions at very small x.

Contribution

It introduces a novel AdS/CFT-based dipole-proton cross section model that fits HERA data with only three parameters and predicts x-independence of structure functions at small x.

Findings

Model fits HERA F_2 data well

Saturation scale becomes x-independent at very small x

Predicts x-independence of F_2 and F_L at small x

Abstract

We show that HERA data for the inclusive structure function F_2(x,Q^2) at small Bjorken-x and Q^2 can be reasonably well described by a color-dipole model with an AdS/CFT-inspired dipole-proton cross section. The model contains only three free parameters fitted to data. In our AdS/CFT-based parameterization the saturation scale varies in the range of 1-3 GeV becoming independent of energy/Bjorken-x at very small x. This leads to the prediction of x-independence of the F_2 and F_L structure functions at very small x. We provide predictions for F_2 and F_L in the kinematic regions of future experiments. We discuss the limitations of our approach and its applicability region, and argue that our AdS/CFT-based model of non-perturbative physics could be viewed as complimentary to the perturbative description of data based on saturation/Color Glass Condensate physics.