Color Glass Condensate at next-to-leading order meets HERA data

TL;DR

This paper presents a comprehensive NLO dipole model fit to HERA data, showing consistent results across different evolution formulations and highlighting the importance of nonperturbative effects for light quarks.

Contribution

It is the first to perform a dipole picture fit to HERA data using full NLO impact factors with improved BK evolution, demonstrating robustness across formulations.

Findings

Different evolution formulations yield similar data descriptions.

Evidence of significant nonperturbative contributions for light quarks.

Predictions remain robust for future experiments.

Abstract

We perform the first dipole picture fit to HERA inclusive cross section data using the full next-to-leading order (NLO) impact factor combined with an improved Balitsky-Kovchegov evolution including the dominant effects beyond leading logarithmic accuracy at low $x$. We find that three different formulations of the evolution equation that have been proposed in the recent literature result in a very similar description of HERA data, and robust predictions for future deep inelastic scattering experiments. We find evidence pointing towards a significant nonperturbative contribution to the structure function for light quarks, which stresses the need to extend the NLO impact factor calculation to massive quarks.