My first post - Hi everyone. I've been reading about boson mass and speed for a couple of hours but I can't seem to find answers. - What is the speed of the W boson during beta decay? If it has a huge mass shouldn't it be a lot slower than leptons? - I assume the electron and antineutrino are travelling close to the speed of light when emitted? - the mass of the W boson is around 80GeV, the electron and antineutrino have masses of around 500KeV. Where does all the extra mass/energy go? Do they have a greater speed? many thanks for reading this.