A Determination of the Top Mass from a Global PDF Analysis

TL;DR

This paper determines the top-quark pole mass through a comprehensive global PDF analysis incorporating NNLO QCD, EW corrections, and various experimental data, achieving a precise measurement.

Contribution

It introduces a novel combined analysis method that refits PDFs to accurately correlate uncertainties in top mass determination from diverse measurements.

Findings

Top-quark mass measured as 172.80 ± 0.26 GeV.

Inclusion of toponium contributions and lattice constraints improves accuracy.

Demonstrates the necessity of refitting PDFs for combined measurements.

Abstract

We present an indirect determination of the top-quark pole mass $m_t$ within a global analysis of parton distribution functions (PDFs), based on the public NNPDF framework. We consider a wide range of measurements, including both single- and double-differential observables, computed at NNLO QCD accuracy with EW corrections, and analyse their individual as well as combined impact on the joint $(\alpha_s, m_t)$ parameter space, while accounting for PDF evolution up to approximate ${\rm N^3LO}$ QCD accuracy with QED corrections. We account for missing higher order QCD uncertainties by default. Unique to our analysis are the inclusion of, first, toponium contributions around the $t\bar{t}$ threshold, second, state-of-the-art constraints on $\alpha_s$ from the lattice, and finally, a detailed sensitivity study of the various ATLAS and CMS differential cross-section measurements at 8 and 13 TeV. We demonstrate explicitly how a combined determination requires the refitting of the PDFs in order to correctly correlate uncertainties. We find $m_t = 172.80 \pm 0.26$ GeV at approximate N$^3$LO QCD including NLO QED, EW and toponium corrections.