Overview
- The CMS Collaboration at CERN reported the most precise W-boson mass using Large Hadron Collider data in a paper published in Nature.
- The value matches Standard Model expectations, undercutting a 2022 outlier reported by Fermilab’s CDF experiment.
- The W boson carries the weak nuclear force, and its mass is about 80 gigaelectronvolts, so even tiny shifts can hint at new physics.
- CMS reached this precision with huge collision samples, fine-grained detector calibration, and tight control of modeling and background errors.
- Global averages and electroweak fits will now fold in the CMS value as other LHC teams, including ATLAS and LHCb, prepare independent checks.