Simple question on W boson decay products

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    Boson Decay W boson
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Discussion Overview

The discussion revolves around the decay products of W bosons and the interactions involving electron neutrinos and electrons. Participants explore the mechanisms of particle interactions, conservation laws, and the nature of virtual particles, focusing on undergraduate-level physics concepts.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions whether an electron neutrino and an electron can annihilate to form a W^- boson, which then decays into a ν_e e^- pair, while noting the importance of lepton number conservation.
  • Another participant agrees that the proposed reaction is possible but mentions that it is not the only mechanism and highlights the potential for W bosons to decay into quarks as well.
  • There is a clarification regarding the nature of the W boson, with a participant suggesting that it is likely virtual, which could limit its final states due to energy and momentum conservation.
  • A participant raises a question about whether the neutrinos involved should be anti-neutrinos instead.
  • Discussion includes the idea that W bosons can only be involved in scattering processes and not in certain direct interactions.
  • There is a comparison made between virtual weak bosons and virtual photons, discussing their roles in force transmission.
  • Another participant inquires about the nature of the interaction, questioning whether it involves a charge transfer between the electron and neutrino or if it is purely a scattering reaction.
  • Questions are raised about the properties of virtual bosons, including their spin and the implications of spin flips during interactions.

Areas of Agreement / Disagreement

Participants express varying views on the nature of W boson interactions, with some agreeing on the possibility of certain reactions while others highlight limitations and alternative mechanisms. The discussion remains unresolved regarding specific details of the interactions and the properties of virtual particles.

Contextual Notes

Participants mention conservation laws such as lepton number, charge, and energy/momentum, but do not resolve the implications of these laws on the proposed interactions. There is also uncertainty regarding the nature of virtual particles and their properties.

adrian52
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Hi,

I'm working on an assignment in which the following reaction takes place:

\nu_e e^- \rightarrow \nu_e e^-

And I'm wondering whether its possible to have an electron neutrino and an electron annihilate to form a W^- boson, after which that boson decays into a \nu_e e^- pair, satisfying the equation? From what I'm reading online it seems like W bosons only decay into electron and anti-electron neutrino pairs, but I figure as long as the lepton number is being conserved (which it is in the above reaction), I don't see any rule stating why it can't work.

My general approach is that if there is no rule saying it can't work, I assume it does (I don't have any other way to operate to be honest). As far as I know I only have to worry about conservation of angular momentum, charge, baryon number, and lepton number for the reactions we're considering (this is all undergraduate level).

Thanks for the help!
 
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adrian52 said:
And I'm wondering whether its possible to have an electron neutrino and an electron annihilate to form a W^- boson, after which that boson decays into a \nu_e e^- pair, satisfying the equation?
Sure.
It is not the only reaction mechanism, however.

From what I'm reading online it seems like W bosons only decay into electron and anti-electron neutrino pairs
That is not true, decays to quarks are possible as well. Note that your W is probably virtual, so its final states might be limited (you cannot produce something that violates energy/momentum conservation).

My general approach is that if there is no rule saying it can't work, I assume it does
That is the general idea, and it works for all processes. Just keep in mind some reactions can be extremely rare.
 
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Thank you, that was very helpful. As a side note let me just say I am really enjoying drawing these Feynman diagrams! :D

Also I was a bit sloppy I think I should not have written 'only', I meant to say in the context of the electron lepton only. Because of course it can decay into muons and tauons and quarks like you said
 
Don't you want these to be anti-neutrinos?
 
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You can have W only as scattering (not s-channel)...Otherwise they will either not interact at all, or they can scatter with some Z0.
 
mfb said:
... Note that your W is probably virtual, so its final states might be limited (you cannot produce something that violates energy/momentum conservation)...
A virtual weak boson... Represents the transmission of the forces of the weak interaction... Of the pair of particles...

And is like a virtual photon for EM ( vs. a real actual live full fledged photon existing on its own, describable by a potentially eternal wave function ) ??
 
adrian52 said:
Hi,

I'm working on an assignment in which the following reaction takes place:

\nu_e e^- \rightarrow \nu_e e^-

...
Is this an interaction where the electron charge is transferred to the neutrino, so that the neutrino is "charged" into an electron... And the electron "discharged" into a neutrino... I.e. They swap roles ?

Or is this a scattering reaction only, where spatial momentum in xyz is transferred via the weak force?
 
Can virtual bosons have off shell SPIN? Would an electron which emits a virtual W boson necessarily spin flip? Would the neutrino need to spin flip to absorb the W? Or could a virtual boson have any energy momentum and angular momentum?
 

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