Measurement of the Z-boson mass

TL;DR

This paper reports a precise measurement of the Z-boson mass using 2016 LHCb data from proton-proton collisions at 13 TeV, employing a template fit to the muon pair mass distribution.

Contribution

First dedicated Z-boson mass measurement at the LHC using the mu+ mu- decay channel with a detailed template fit approach.

Findings

Measured Z-boson mass: 91185.7 ± 8.3 (stat) ± 3.9 (sys) MeV

Result consistent with previous measurements and electroweak fits

Demonstrates LHCb's capability for precision electroweak measurements

Abstract

The first dedicated $Z$-boson mass measurement at the LHC with $Z \to \mu^+\mu^-$ 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 $\mu^+\mu^-$ 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.