Precision Physics

Precision measurement of the Z boson invisible width at the CMS experiment (CMS-PAS-SMP-18-014)

This result is the first measurement of the Z invisible width at a hadron collider and is the single most precise direct measurement in the world, competitive with the combined direct measurement from the LEP experiments. The invisible width is measured to be 523±3(stat)±16(syst) MeV.

Covered in CERN courier and CMS highlights

Measurement of Z/γ ratio and collinear Z emission at the CMS experiment (arXiv:2102.02238)

This result presents the first measurement of the ratio of the differential cross sections of Z + jets and γ + jets production at 13 TeV of LHC, as well as the first direct measurement of Z bosons emitted collinearly with a jet at the LHC.

Measurement of the W Boson Width in proton-antiproton collisions at the Tevatron, CDF collaboration, Phys. Rev. Lett. 100, 071801 (2008)

This measurement is the most precise direct measurement of the W boson width. The result is ΓW = 2032 ± 45(stat) ± 57(syst) MeV, consistent with the standard model expectation.

Precision Measurement of the W-Boson Mass with the CDF II Detector, CDF Collaboration, Phys. Rev. Lett. 108, 151803 (2012)

This is the most precise measurement of the W-boson mass to date and significantly exceeds the precision of all previous measurements combined. The measured value is 80 387±19 MeV.