PDF uncertainties on the W boson mass measurement from the lepton transverse momentum distribution

TL;DR

This paper evaluates how uncertainties in proton parton distribution functions affect the measurement of the W boson mass via the lepton transverse momentum distribution, highlighting the variability across different PDF sets.

Contribution

It provides a comprehensive analysis of PDF-induced uncertainties on the W mass measurement, combining multiple PDF sets to assess the overall impact and variability.

Findings

Uncertainty on MW ranges between +-18 and +-24 MeV depending on conditions.

Some PDF sets predict uncertainties around 10 MeV.

Significant spread in central values among different PDF groups.

Abstract

We study the charged current Drell-Yan process and we evaluate the proton parton densities uncertainties on the lepton transverse momentum distribution and their impact on the determination of the W-boson mass. We consider the global PDF sets CT10, MSTW2008CPdeut, NNPDF2.3, NNPDF3.0, MMHT2014, and apply the PDF4LHC recipe to combine the individual results, obtaining an uncertainty on MW that ranges between +-18 and +-24 MeV, depending on the final state, collider energy and kind. We discuss the dependence of the uncertainty on the acceptance cuts and the role of the individual parton densities in the final result. We remark that some PDF sets predict an uncertainty on MW of O(10 MeV); this encouraging result is spoiled, in the combined analysis of the different sets, by an important spread of the central values predicted by each group.