AAMQS: A non-linear QCD analysis of new HERA data at small-x including heavy quarks

TL;DR

This paper performs a comprehensive analysis of small-x electron-proton scattering data using a non-linear QCD framework, incorporating heavy quark effects and variable flavor schemes to improve data description.

Contribution

It extends previous models by including heavy quark contributions and a variable flavor scheme within the dipole and BK equation framework.

Findings

Achieved a good fit to HERA data including heavy quark effects.

Found that heavy quark distributions have a smaller transverse radius than light quarks.

Maintained stable fit parameters compared to previous light-quark-only analyses.

Abstract

We present a global analysis of available data on inclusive structure functions and reduced cross sections measured in electron-proton scattering at small values of Bjorken-x, x<0.01, including the latest data from HERA on reduced cross sections. Our approach relies on the dipole formulation of DIS together with the use of the non-linear running coupling BK equation for the description of the small-x dynamics. We improve our previous studies by including the heavy quark (charm and beauty) contribution to the reduced cross sections, and also by considering a variable flavor scheme for the running of the coupling. We obtain a good description of data, the fit parameters remaining stable with respect to our previous analyses where only light quarks were considered. The inclusion of the heavy quark contributions resulted in a good description of available experimental data for the charm component of the structure function and reduced cross section provide the initial transverse distribution of heavy quarks was allowed to differ (more specifically, to have a smaller radius) from that of the light flavors.