High-precision measurement of the <i>W</i> boson’s mass lends weight to the standard model

The W boson is a subatomic particle responsible for the weak nuclear force, which governs processes from radioactive decay to the nuclear reactions that power the Sun. According to the standard model of particle physics, which is the conventional theory of fundamental particles and forces, this force is much weaker than electromagnetism because the W boson is heavy, with a mass comparable to that of an iron nucleus — around 80 gigaelectronvolts (GeV). In a paper in Nature, the Compact Muon Solenoid (CMS) Collaboration1 reports the most precise measurement of the mass of the W boson so far, made at the Large Hadron Collider (LHC) at CERN, Europe’s particle-physics laboratory near Geneva, Switzerland. The result aligns with the standard model and challenges an anomalous measurement2 reported in 2022 by the collaboration at the Fermi National Accelerator Laboratory (Fermilab) near Chicago, Illinois, that ran the Collider Detector at Fermilab (CDF) experiment.

Nature 652, 306-307 (2026)

doi: https://doi.org/10.1038/d41586-026-00630-9

References The CMS Collaboration. Nature 652, 321–327 (2026). CDF Collaboration et al. Science 376, 170–176 (2022). Particle Data Group. Phys. Rev. D 110, 030001 (2024). ATLAS Collaboration. Eur. Phys. J. C 78, 110 (2018). The LHCb collaboration. J. High Energy Phys. 2022, 36 (2022). Atlas Collaboration. Eur. Phys. J. C 84, 1309 (2024). The ALEPH Collaboration, The DELPHI Collaboration, The L3 Collaboration, The OPAL Collaboration & The LEP Electroweak Working Group. Phys. Rep. 532, 119–244 (2013). Abazov, V. M. et al. Phys. Rev. Lett. 108, 151804 (2012). LHC-TeV MW Working Group. Eur. Phys. J. C 84, 451 (2024). Abada, A. et al. Eur. Phys. J. C 79, 474 (2019). Shen, P. X. et al. Eur. Phys. J. C 80, 66 (2020). Download references

Competing Interests The authors declare no competing interests.

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