Extraction of the proton parton density functions using a NLO-QCD fit of the combined H1 and ZEUS inclusive DIS cross sections

TL;DR

This paper performs a NLO-QCD fit to combined H1 and ZEUS inclusive DIS data, producing highly precise proton parton distribution functions with reduced experimental uncertainties.

Contribution

It introduces a combined analysis of H1 and ZEUS data with a consistent systematic uncertainty treatment, yielding more accurate PDFs than previous separate analyses.

Findings

Reduced experimental uncertainties in PDFs

High-precision HERAPDFs compared to global fits

Effective systematic uncertainty management

Abstract

The combined HERA-I data set, of neutral and charged current inclusive cross-sections for $e^+p$ and $e^-p$ scattering, is used as the sole input for a next-to-leading order (NLO) QCD parton distribution function (PDF) fit. The consistent treatment of systematic uncertainties in the joint data set ensures that experimental uncertainties on the PDFs can be calculated without need for an increased $\chi^2$ tolerance. This results in PDFs with greatly reduced experimental uncertainties compared to the separate analyses of the ZEUS and H1 experiments. Model uncertainties, including those arising from parametrization dependence, are also carefully considered. The resulting HERAPDFs have impressive precision compared to the global fits.