Quanta Magazine: Newly Measured Particle Seems Heavy Enough to Break Known Physics

CDF’s new mass measurement is based on an analysis of about 4 million W bosons produced at the Tevatron between 2002 and 2011. When the Tevatron crashed protons into antiprotons, a W boson often popped up in the ensuing commotion. The W could then decay into a neutrino and either a muon or an electron, both straightforward to detect. The faster the muon or electron, the heavier the W boson that produced it.