I have been looking at the Beta decay process and can't see how energy is conserved. The W boson, for example, is many times more massive than all of the other particles together. But how does that additional mass/energy come about and where does it go to? I'm guessing that it gets its mass from the Higgs field and or that it borrows its mass in accordance with the uncertainty principle. I have found loads of sources describing Beta decay but none addressing energy conservation when the event is described in terms of Bosons. Thanks to anyone who replies.