We present a comparative analysis of the impact of the non-perturbative intrinsic charm quark content of the proton on differential cross section of γ + c-jet in pp and pp collisions, for the kinematic regions that are sensitive to this contribution. We discuss the Q 2 evolution of intrinsic quark distributions at the next-to-leading order (NLO) and present a code which provide these distributions as a function of x and Q 2 for any arbitrary Fock state probability. For the pp collisions at the Tevatron, the results are compared with the recent experimental data of D0 at √ s = 1.96 TeV and also predictions for pp collisions at √ s = 8 TeV and √ s = 13 TeV for the LHC.

The recent measurement of the differential γ + 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 in 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 2 c on the PDFs and compare the results with those from the analysis of Tevatron data. We show that both of them have the same impact on the PDFs, and thus can be recognized as the same evidence for the inefficiency of perturbative QCD in dealing with charm production in some kinematic regions.

Having a precise knowledge of the charm quark component can lead to a better understanding of the fundamental structure of the nucleon. Furthermore, the charm quark distribution function plays an important role in the study of many processes which are sensitive to the charm quark content of the nucleon. In the standard global analysis of parton distribution functions (PDFs), the charm quark distribution arises perturbatively through the splitting of the gluon into charm-anticharm pairs in the DGLAP evolution equations. Nevertheless, the existence of nonperturbative intrinsic charm quarks in the proton has also been predicted by QCD. In this paper, we study some phenomenological models within the light-cone framework to predict the nonperturbative intrinsic charm quark content of the nucleon. We investigate the impact of these models on the prediction of γ+c-jet production in pp collisions at the LHC and compare our results on pp̄→γ+c-jet with the experimental data of D0.

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