From what I understand, which is kind of limited, the neutron (939Mev) decays into a proton (938Mev) giving off a HUGELY massive particle called a W boson (80,000Mev). The W boson exists for 3*10^-25 seconds then gets transformed into an electron (.511Mev) and an electron anti-neutrino (.28ev). My question is where does all that mass/energy of the boson go, and where does it get it from? The electron and neutrino are tiny but has lots of kinetic energy, surely it didn't convert all that 80,000Mev to the kinetic energy of the electron and neutrino? Another question: in the Feynman diagram, why is the anti-neutrino shown going backward in time?