What happens to the rest of the mass in Beta+ decay involving a W+ boson?

[oksuz_]

In Beta+ decay, a W+ boson is created and it decays into positron and electron neutrino. Mass of W+ boson is ~ 80 GeV/c^2, however, the total mass of positron and electron neutrino is very small compared to it. So, what happens to the rest of the mass? Is it converted into kinetic energy of positron and electron neutrino? I do not know much about field theory. Therefore, I may be asking a silly question.

Thanks in advance.

 

[mfb]

It is a virtual W boson - it doesn't actually exist, and it doesn't have a well-defined mass either. The total energy involved in a beta decay is much smaller than 80 GeV anyway.
The energy released in the decay partially goes into the mass of the positron and the neutrino and partially in the kinetic energy of these particles (and the nucleus).

 

[oksuz_]

I am confused. The source below says that it is a fundamental particle, discovered 30 years ago.

https://home.cern/news/news/experiments/w-boson-published-30-years-ago And, I still do not quite understand why its mass is huge compared to the decay product.

Thanks.

 

[jtbell]

It's the difference between "virtual" particles and "real" particles. A "real" W has a mass of about 80 GeV/c². A "virtual" W, such as appears in Feynman diagrams of beta decay, or neutrino/antineutrino scattering from protons, neutrons, etc., does not have a well-defined mass. Particle physicists have another terminology for the difference: "real" = "on the mass shell" and "virtual" = "off the mass shell". This distinction occurs also with other kinds of "exchange" particles.