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

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    Beta Boson Decay
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Discussion Overview

The discussion revolves around the mass dynamics in Beta+ decay, specifically concerning the role of the W+ boson and the fate of its mass during the decay process. Participants explore concepts related to particle physics, virtual particles, and energy conservation in the context of this decay mechanism.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant notes that in Beta+ decay, a W+ boson is produced, which decays into a positron and an electron neutrino, raising the question of what happens to the remaining mass of the W+ boson.
  • Another participant clarifies that the W boson involved in the decay is virtual and does not have a well-defined mass, suggesting that the energy released in the decay is distributed between the mass of the decay products and their kinetic energy.
  • A third participant expresses confusion regarding the classification of the W boson as a fundamental particle and its relatively large mass compared to the decay products, referencing external sources for clarification.
  • A later reply emphasizes the distinction between "real" and "virtual" particles, explaining that a real W boson has a defined mass, while a virtual W boson does not, and this distinction is relevant in the context of particle interactions.

Areas of Agreement / Disagreement

Participants exhibit some disagreement regarding the interpretation of the W boson's mass and its classification as virtual versus real. The discussion remains unresolved, with differing perspectives on the implications of these concepts in Beta+ decay.

Contextual Notes

There are limitations in the understanding of the mass-energy relationship in this decay process, particularly regarding the definitions of virtual and real particles and the implications for energy distribution among decay products.

oksuz_
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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.
 
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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).
 
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.
 

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