The Large Hadron Collider has measured the Z boson mass of 91.18842 ± 0.00093 GeV, which is about twice as precise as the previous world average, and slightly higher (by about one part per 217,114).
This compares to the LEP value from the year 2006 of 91.1876 ± 0.0021 GeV, the CDF value from Tevatron from the year 2022 of 91.1923 ± 0.0071 GeV, and the PDF world average of those two values of 91.1880 ± 0.0020 GeV. The new LHC measurement is consistent with the previous world average and with the two measurements that went into forming that world average.
The new inverse error weighted global average Z boson mass should be about 91.18829 ± 0.0008 GeV.
The first dedicated Z-boson mass measurement at the LHC with Z→μ+μ− 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 μ+μ− mass distribution yields the following result for the Z-boson mass, m(Z) = 91184.2 ± 8.5 ± 3.8 MeV, where the first uncertainty is statistical and the second systematic. This result is consistent with previous measurements and predictions from global electroweak fits.
LHCb Collaboration, "Measurement of the Z-boson mass" arXiv:2505.15582 (May 21, 2025).
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