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

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.