Single Top Production in PDF fits

TL;DR

This paper assesses how recent LHC single top-quark measurements influence proton PDFs, analyzing data consistency and the impact of theoretical corrections within the NNPDF3.1 framework.

Contribution

It introduces a systematic approach to incorporate single top data into PDF fits, optimizing data selection for better constraints on PDFs.

Findings

Optimal data combinations improve PDF constraints.

Single top data significantly affect up, down, and gluon PDFs.

Theoretical corrections impact the data description and fit quality.

Abstract

We study the impact of recent LHC $t$-channel single top-quark and top-antiquark measurements at centre-of-mass energies of 7, 8 and 13 TeV on the parton distribution functions (PDFs) of the proton. We consider, namely, total cross sections, top-antitop cross section ratios, and differential distributions. We present a critical appraisal of the data, studying in particular how their description is affected by the theoretical details that enter the computation of the corresponding observables: QCD and electroweak higher-order corrections, the flavour scheme, and the value of the bottom-quark threshold. We perform a series of fits to the data within the NNPDF3.1 framework, whereby next-to-next-to-leading order QCD corrections are applied to single top measurements in a systematic way. We find that there exists an optimal combination of data that maximises consistency with the rest of the dataset, and efficiency in constraining the up, down and, partially, gluon PDFs.