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Are these reactions allowed?

  1. Mar 27, 2009 #1
    Hi guys,

    Standard Model

    Is this reaction allowed or not? If yes, how do we represent this on Feynman diagram?

    (electron) + (photon) ------> (muon negative) + (electron) + positron

    What about this reaction?

    (muon neutrino) + (electron antinetrino) -----> (muon negative) + (positron)

    What are the rules for the construction of Feynman diagrams?
    What conservation rules do I need to know?
    It would be good if anyone can explain this through Feynman diagrams with a few words. Thanks a lot!
  2. jcsd
  3. Mar 27, 2009 #2


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    is this homework / course work?

    Both are not allowed. You need to know about lepton familily number conservation and that weak neutral current (Z boson) couple to same lepton-antilepton pairs (for instance eletron + positron, electron neutrino + anti electron neutrino)
  4. Mar 27, 2009 #3
    Within the standard model, the lepton number of each family (electron-like + neutrino-like) is conserved.
  5. Mar 27, 2009 #4
    #1 is not allowed to the first order because muon lepton number is not conserved.

    #2 is allowed, muon neutrino emits virtual W+ and turns into muon, electron antineutrino eats virtual W+ and becomes a positron. Cross-section is very low.
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