Impact of the top quark cross section data on parton distribution functions

TL;DR

This paper investigates how recent top quark pair production cross section measurements from the LHC and Tevatron influence the parton distribution functions (PDFs) using Hessian profiling, revealing significant constraints on certain PDFs.

Contribution

It applies Hessian profiling to assess the impact of top quark data on various PDF sets, highlighting the constraints on gluon and s-quark distributions.

Findings

Significant constraints on gluon and s-quark PDFs in CT14 and MMHT2014 sets.

No impact observed on NNPDF3.0 PDFs.

Limited constraint on the $ar u$-sea quark distribution in CT14.

Abstract

Recent measurements of top quark pair production cross section, which is performed at the LHC and the Tevatron collider, are studied using Hessian profiling technique to obtain their impact on the parton distribution functions (PDFs). The top quark production data covers different center-of-mass energies $\sqrt{s}$= 1.96, 5.02, 7, 8 and 13 TeV in either $pp$ or $p\bar{p}$ collisions. It is explained how the Hessian profiling method may be used to assess the impact of these new data on PDFs and consequently on their predictions. In this research, the impact of recent measurements of top quark pair cross sections on different CT14, MMHT2014, and NNPDF3.0 PDF sets is investigated. The analysis results show that the recent top quark production at the LHC and Tevatron data provide significant constraints in particular on the central value, relative uncertainties or both for the $s$-quark distribution and the gluon PDFs in both of CT14, MMHT2014 PDF sets and are insensitive to valence quark PDFs. A small constraint on the $\bar u$- sea quark distribution for CT14 PDF is also observed. There is no impact on the NNPDF3.0 PDF set in presence of these data.