The impact of ATLAS and CMS single differential top-quark pair measurements at $\sqrt{s}=8$ TeV to CTEQ-TEA PDFs

TL;DR

This paper assesses how top-quark pair production measurements from ATLAS and CMS at 8 TeV influence the gluon parton distribution functions in the CT14HERA2 PDFs, revealing limited impact with standard data but significant constraints when data are weighted or jet data are excluded.

Contribution

It introduces the application of the Error PDF Updating Method to evaluate the impact of top-quark pair data on PDFs, highlighting the conditions under which these measurements provide substantial constraints.

Findings

Top-quark pair data provide minor constraints when included with jet data.

Removing jet data enhances the impact of top-quark measurements on PDFs.

Weighted top-quark data significantly constrain the gluon distribution.

Abstract

By applying the Error PDF Updating Method, we analyze the impact of the absolute and normalized single differential cross-sections for top-quark pair production data from the ATLAS and CMS experiments at the Large Hadron Collider, at a centre-of-mass energy of $\sqrt{s}= 8$ TeV, on the CT14HERA2 PDFs. We find that the top quark pair single differential distributions provide minor constraints on the CT14HERA2 gluon PDF when the nominal CT14HERA2 inclusive jet production data are included in the fit. Larger constraints on the gluon distribution are present when the jet data are removed (CT14HERA2mJ) and/or when increased weights are given to the top data in the CT14HERA2 fits. The weighted $t\bar t$ data provide significant constraints on the CT14HERA2mJ gluon PDF, that are comparable to those obtained from inclusive jet production data. Furthermore, we examine the top quark mass sensitivity of the top-quark pair single differential distributions.