W+ or W- in neutrino collisions

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Discussion Overview

The discussion revolves around the role of W bosons in neutrino collisions, particularly focusing on whether a W+ or W- boson is involved in the interaction between a neutron and a neutrino. Participants explore the implications of these particles in various decay processes and interactions, including beta decay and electron capture.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions whether a W- boson could also be involved in a neutron-neutrino collision, suggesting that it might allow the neutron to become a proton by taking away negative charge.
  • Another participant asserts that the W boson in Feynman diagrams is "virtual" and can be interpreted as either a W+ or W-, indicating no significant difference in this context.
  • A participant references beta minus decay, explaining that a proton emits a W- to become a neutron, which then decays into an electron and an anti-electron neutrino, suggesting that this process necessitates a W- boson.
  • Further discussion highlights that in electron capture, a proton emits a W+ to convert an electron into a neutrino, raising questions about the nature of the W boson in these interactions.
  • One participant proposes that the same physical process can be represented with either a W- or W+, depending on the perspective taken, emphasizing that this does not alter the underlying physics or calculations.

Areas of Agreement / Disagreement

Participants express differing views on the interpretation of W bosons in neutrino collisions, with some suggesting that the sign of the W boson is a matter of perspective rather than a fundamental difference. The discussion remains unresolved regarding the implications of using W+ versus W- in these contexts.

Contextual Notes

There are limitations in the discussion regarding the assumptions made about the nature of virtual particles and the interpretations of Feynman diagrams, which are not fully explored or defined.

mrcotton
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All the Feynman diagrams I have seen so far for a neutron colliding with a neutrino have a w+ with an arrow from the neutrino to the neutron.
Would it not also be possible with a W- leaving the neutron taking away negative charge for it to become a positive proton or is there some quantum rule I am not aware of that forbids this?

Any help gratefully received.
 
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The W in a Feynman diagram like that one is "virtual" and can be interpreted either as a W+ going one way, or a W- going the other way. There's no difference as far as I know.
 
Hi jtbell,
thanks for the rapid response,

What confuses me is that for example in say beta minus decay. The proton turns to a neutron by emitting a W- and this W- decays to become an electron and a anti-electon neutrino. The electron in a sense is formed from the "negativness" of the W-. So in this type of decay it must be a W-.
Also in electron capture it seems that the proton captures the electron by emitting a W+ to turn the electron into a neutrino, with this process happening to protons in a neucleus. Yet if a free electron and a proton collide via the weak interaction then a W- leaves the electron.

So do you mean there is no difference in the initial and final states or do you mean its the same W we just assigne a sign to it.

I hope this garbled rant makes sense
confused of planet Earth
 
What confuses me is that for example in say beta minus decay. The proton turns to a neutron by emitting a W- and this W- decays to become an electron and a anti-electon neutrino. The electron in a sense is formed from the "negativness" of the W-. So in this type of decay it must be a W-.
You can write the same process as W+, electron and antineutrino appearing out of nowhere, and then an interaction where the neutron "absorbs" the W+ and becomes a proton.
That is an unconventional way to draw the Feynman diagram, but it is the same physics and does not change the calculation at all.
So do you mean there is no difference in the initial and final states or do you mean its the same W we just assigne a sign to it.
It is the same process.
 

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