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Homework Help: Feynman diagram

  1. Apr 27, 2008 #1


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    1. The problem statement, all variables and given/known data

    What observation of the process: (anti muon neutrino) + (electron) -> (anti muon neutrino) + (electron) constitutes unambiguous evidence for weak neutral currents,

    whereas the observation of (anti electron neutrino) + (electron) -> (anti electron neutrino) + (electron)

    3. The attempt at a solution

    The solution is the first one:


    Since the second reaction can undergo via W+ as well as Z0:


    My question is in the Feynman diagrams, why could you not have this for example:

    An electron decaying to a muon neutrino ?


    Apparently the weak interaction also violates charge conservation, but I have never seen a possible reaction with a Feynman diagram that is violated at the vertices's.

    Many thanks for any help :)
  2. jcsd
  3. Apr 27, 2008 #2


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    The weak interaction does NOT violate charge conservation! So your third diagram is impossible. Charge is always conserved
  4. Apr 27, 2008 #3


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    Thanks for that, I was a bit uneasy to see charge violation.

    Does weak violate anything to do with charge? I remember seeing something about charge violation that only the weak does not strong or e.m

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