Measurement of the Z-boson mass

Abstract

The first dedicated $Z$-boson mass measurement at the LHC with $Z\to \hat{I}{¼}^{+}\hat{I}{¼}^{-}$ decays is reported. The dataset uses proton-proton collisions at a centre-of-mass energy of $13$ TeV, recorded in 2016 by the LHCb experiment, and corresponds to an integrated luminosity of $1.7$ fb${}^{-1}$. A template fit to the $\hat{I}{¼}^{+}\hat{I}{¼}^{-}$ mass distribution yields the following result for the $Z$-boson mass, \begin{equation*} m_{Z} = 91185.7 \pm 8.3 \pm 3.9 \rm{MeV}, \end{equation*} where the first uncertainty is statistical and the second systematic. This result is consistent with previous measurements and predictions from global electroweak fits.

All figures and tables, along with machine-readable versions and any supplementary material and additional information, are available at https://lbfence.cern.ch/alcm/public/analysis/full-details/4319 (LHCb public pages)