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 uncertainty1, 2–3. 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 collider4. 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.

Druzhkin, D., Borshch, V., Babaev, A., Uzunian, A., Slabospitskii, S., Kachanov, V., et al. (2026). High-precision measurement of the W boson mass with the CMS experiment. NATURE, 652(8109), 321-327 [10.1038/s41586-026-10168-5].

High-precision measurement of the W boson mass with the CMS experiment

Tabarelli de Fatis T.;Ragazzi S.;Pizzati G.;Pinolini B. S.;Perego A.;Palluotto S.;Paganoni M.;Moroni L.;Malberti M.;Lucchini M. T.;Lavizzari G.;Guzzi L.;Govoni P.;Ghezzi A.;Gerosa R.;Dinardo M. E.;De Guio F.;Cetorelli F.;Brivio F.;Xiao J.;
2026

Abstract

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 uncertainty1, 2–3. 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 collider4. 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.
Articolo in rivista - Articolo scientifico
Elementary Particles; Protons; Uncertainty
English
8-apr-2026
2026
652
8109
321
327
open
Druzhkin, D., Borshch, V., Babaev, A., Uzunian, A., Slabospitskii, S., Kachanov, V., et al. (2026). High-precision measurement of the W boson mass with the CMS experiment. NATURE, 652(8109), 321-327 [10.1038/s41586-026-10168-5].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/605266
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