Compact Muon Solenoid: A photo of the CMS detector taken during one of the Large Hadron Collider's shutdowns. (Courtesy: C Paus) Physicists have determined the mass of the W boson with the highest precision yet by analysing more than a billion proton collision events at CERN’s Large Hadron Collider (LHC). The new result confirms a prediction from the Standard Model of particle physics while refuting a comparably precise measurement made by Fermilab’s CDF Collaboration in 2022. This is significant because the older measurement, which used data from the defunct Tevatron collider, differed from the Standard Model’s predictions by seven standard deviations, suggesting that the W boson might be far heavier than the model allows. The W boson is one of two elementary particles that acts as a carrier for the weak force (the other is the Z boson).…