The CMS experiment at CERN has made its first measurement of the W boson mass, a fundamental particle that mediates the weak force. The result is the most precise measurement made so far at the Large Hadron Collider (LHC) and is in line with predictions from the Standard Model of particle physics.
The W boson mass was measured by analyzing proton-proton collision data from the second run of the LHC. The result, 80,360.2 million electronvolts (MeV) with an uncertainty of 9.9 MeV, is comparable in precision to previous measurements made by other experiments.
This measurement is important because it allows scientists to test whether the properties of the W boson align with those predicted by the Standard Model. If they don’t, it could indicate new physics phenomena, such as new particles or interactions.
The CMS experiment’s result builds on previous measurements made by other collider experiments at CERN and elsewhere. The ATLAS collaboration released an improved measurement in 2023 based on reanalyzed data from the first run of the LHC, which aligned with all previous measurements except one from the CDF experiment.
The CMS spokesperson, Patricia McBride, said that the team’s hard work resulted in a precise W mass measurement and the most precise measurement at the LHC. The result showcases the exceptional performance of the LHC and its detectors, pushing the precision frontier and testing the Standard Model.
Further data from the ongoing third run of the collider and its upgrade, the High-Luminosity LHC, is expected to push this frontier further.
Source: https://phys.org/news/2024-09-cms-cern-boson-mass.html