In an earlier publication, we introduced the software package, ePump (error PDF Updating Method Package), that can be used to update or optimize a set of parton distribution functions (PDFs), including the best-fit PDF set and Hessian eigenvector pairs of PDF sets (i.e., error PDFs), and to update any other set of observables, in the Hessian approach. Here, we validate the ePump program with a detailed comparison against a full global analysis, and we demonstrate the potential of ePump by presenting selected phenomenological applications relevant to the Large Hadron Collider. For example, we use the package to estimate the impact of the recent LHC data of the measurements of W , Z boson and top quark pair differential distributions on the CT14HERA2 PDFs.

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LHC data have the potential to provide constraints on the gluon distribution, especially at high x, with both ATLAS and CMS performing differential measurements. Recently, CMS has measured double-differential distributions at 8 TeV. In this paper we examine the impact of this data set on the gluon distribution. To that end we develop novel, double-differential NNLO predictions for that data. No significant impact is found when the CMS data is added to the CT14HERA2 global PDF fit, due to the larger impact of the inclusive jet data from both the Tevatron and the LHC. If the jet data are removed from the fit, then an impact is observed. If the CMS data is scaled by a larger weight, representing the greater statistical power of the jet data, a roughly equal impact on the gluon distribution is observed for the as for the inclusive jet data. For data samples with higher integrated luminosity at 13 TeV, a more significant impact of the double-differential data may be observed.

A study of the impact of double-differential top distributions from CMS on parton distribution functions Micha l Czakon (a,1) , Sayipjamal Dulat (b,2) , Tie-Jiun Hou (c,3) , Joey Huston (d,4) , Alexander Mitov (e,5) , Andrew S. Papanastasiou (e,f,6) , Ibrahim Sitiwaldi (a,7) , Zhite Yu (d,8) , and C.-P. Yuan (d,9) *

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