High-precision measurement of the W boson mass with the CMS experiment
- V. Chekhovsky
- A. Hayrapetyan
- V. Makarenko
- A. Tumasyan
- W. Adam
- J. W. Andrejkovic
- L. Benato
- T. Bergauer
- S. Chatterjee
- K. Damanakis
- M. Dragicevic
- P. S. Hussain
- M. Jeitler
- N. Krammer
- A. Li
- D. Liko
- I. Mikulec
- J. Schieck
- R. Schöfbeck
- D. Schwarz
- M. Sonawane
- W. Waltenberger
- C.-E. Wulz
- T. Janssen
- H. Kwon
- T. Van Laer
- P. Van Mechelen
- N. Breugelmans
- J. D’Hondt
- S. Dansana
- A. De Moor
- M. Delcourt
- F. Heyen
- Y. Hong
- S. Lowette
- I. Makarenko
- D. Müller
- S. Tavernier
- M. Tytgat
- G. P. Van Onsem
- S. Van Putte
- D. Vannerom
- B. Bilin
- B. Clerbaux
- A. K. Das
- I. De Bruyn
- G. De Lentdecker
- H. Evard
- L. Favart
- P. Gianneios
2026-04-08
In the standard model of particle physics, the masses of the W and Z bosons, the carriers of the weak interaction, are uniquely related. A precise determination of their masses is important because quantum loops of heavy, undiscovered particles could modify this relationship. Although the Z mass is known to the remarkable precision of 22 parts per million (2.0 MeV), the W mass is known much less precisely. A global fit to measured electroweak observables predicts the W mass with 6 MeV uncertainty 1–3 . Reaching a comparable experimental precision would be a sensitive and fundamental test of the standard model, made even more urgent by a recent challenge to the global fit prediction by a measurement from the CDF Collaboration at the Fermilab Tevatron collider 4 . Here we report the measurement of the W mass by the CMS Collaboration at the CERN Large Hadron Collider, based on a large data sample of W → μν events collected in 2016 at the proton–proton collision energy of 13 TeV. The measurement exploits a high-granularity maximum likelihood fit to the kinematic properties of muons produced in W decays. By combining an accurate determination of experimental effects with marked in situ constraints of theoretical inputs, we reach a precise measurement of the W mass, of 80,360.2 ± 9.9 MeV, in agreement with the standard model prediction.