A Study of the PDF uncertainty on the LHC W-boson mass measurement

Abstract

The determination of the $W$-boson mass through an analysis of the decay charged-lepton transverse momentum distribution has a sizable uncertainty due to the imperfect knowledge of the relevant parton distribution functions (PDFs). In this paper, a quantitative assessment of the $W$-boson mass uncertainty at the LHC resulting from the PDF uncertainty is examined. We use the CT14 NNLO PDFs with a NNLL + NNLO calculation (ResBos) to simulate the $W$-boson production and decay kinematics. The uncertainty of the $W$-boson mass determination is then determined as a function of the boson and lepton kinematics. For $W^{+}$ production using $P_T^W<15$ GeV and $35<P_T^l$ (GeV) $<45$, PDF uncertainties (at the 68% CL) of ${}_{-17.5}^{+16.0}$ MeV, ${}_{-14.8}^{+13.9}$ MeV, and ${}_{-19.2}^{+12.2}$ MeV, are determined at 7 TeV, 8 TeV and 13 TeV respectively. The uncertainties of $W^{-}$ for the same cuts are found to be ${}_{-15.6}^{+15.9}$ MeV, ${}_{-12.7}^{+15.0}$ MeV and ${}_{-15.3}^{+14.8}$ MeV, at 7 TeV, 8 TeV and 13 TeV respectively.

Comments: 16 pages, 3 figures, 3 tables