The uncertainty of parton distribution functions due to physical observables in a global analysis

TL;DR

This paper analyzes how recent collider measurements and older data influence the uncertainties in proton parton distribution functions, revealing inconsistencies and limitations of perturbative QCD in certain regions.

Contribution

It provides a comprehensive NLO global QCD analysis showing the impact of new and old data on PDFs and highlights inconsistencies in high-precision measurements.

Findings

Significant impact of Tevatron data on gluon and charm PDFs

Inconsistency between HERA combined data and Tevatron measurements

Both old EMC and Tevatron data suggest limitations of perturbative QCD in charm production

Abstract

The recent measurement of the differential $ \gamma+c $-jet cross section, performed at the Tevatron collider in Run II by the D0 collaboration, is studied in a next-to-leading order (NLO) global QCD analysis to assess its impact on the proton parton distribution functions (PDFs). We show that these data lead to a significant change on the gluon and charm quark distributions. We demonstrate also that there is an inconsistency between the new high precision HERA I+II combined data and Tevatron measurement. Moreover, in this study we investigate the impact of older EMC measurements of charm structure function $F_{c}^{2}$ on the PDFs and compare the results with those gaining from the analysis of Tevatron data. We show that both of them have a same impact on PDFs, and thus can be recognized as same evidences for inefficiency of perturbative QCD in dealing with the charm production in some kinematic regions.