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Allowed Reactions

  1. Nov 16, 2007 #1
    I would really just like to know if I'm on the right track here in terms of if reactions can go ahead or not... The reactions are in latex and my thoughts are below each one..
    1. The problem statement, all variables and given/known data
    For each of the following processes say whether it is a strong, electromagnetic or weak process or whether it is forbidden in the standard model and explain the reasons.

    Process 1
    [tex]K^{0} \rightarrow \pi^{+}+e^{-}[/tex]
    Charge conserved
    Mass conserved
    Lepton Number - not conserved
    Baryon Number - no baryons
    Spin - (-1/3)(1/3) -> (2/3)(1/3) + (1/2) not conserved
    Strangeness - not conserved
    Therefore not possible
    It would have been a weak interaction though?

    Process 2
    [tex]e^{-}+p \rightarrow n+\upsilon_{\mu}[/tex] (the final thing should be a muon neutrino)
    Charge conserved
    Mass conserved
    Lepton Number - not conserved
    Baryon Number - conserved
    Spin - (1/2) + (1/2) -> (1/2) + (0) not conserved
    Strangeness - conserved
    Therefore not possible
    It would have been a weak interaction though?

    Process 3
    [tex]\Delta^{0} \rightarrow \pi^{+}+n[/tex]
    Charge conserved
    Mass conserved
    Lepton Number - no leptons
    Baryon Number - conserved
    Spin - ???? -> 0 + (1/2) no idea
    Strangeness - conserved
    Therefore possible? (dependent on spin)
    It would be a weak interaction

    Process 4
    [tex]K^{0} + n \rightarrow \Lambda + \pi^{0}[/tex]
    Charge conserved
    Mass conserved
    Lepton Number - no leptons
    Baryon Number - ????????
    Spin - ??????????
    Strangeness - not conserved (s in the K, anti-s in the lambda)
    Therefore possible? (dependent on spin & baryon number)
    It would be a weak interaction

    Process 5
    [tex]\Xi^{0} \rightarrow \Lambda + \pi^{0}[/tex]
    Charge conserved
    Mass conserved
    Lepton Number - no leptons
    Baryon Number - ????????
    Spin - ??????????
    Strangeness - not conserved (ss in the Xi, s in the lambda)
    Therefore possible? (dependent on spin)
    It would be a weak interaction


    Also, In what situation would it be a strong interaction?
     
  2. jcsd
  3. Nov 16, 2007 #2
    Actually, I think processes 3,4 and 5 are strong interactions rather than weak...
     
  4. Nov 16, 2007 #3
    Okay, process 3 also isn't possible due to the delta having spin 3/2, the pion having spin 0 and the neutron having spin 1/2 so this is also impossible due to spin not being conserved?

    Process 4
    Baryon Number 0 + 1 -> 1 + 0, conserved
    Spin 0 + 1/2 -> 1/2 + 0, conserved
    So process 4 is possible...

    Process 5
    Baryon Number 1 -> 1 + 0 conserved
    Spin - can't find out the spin for Xi, -> 1/2 + 0
    So it's not possible due to lack of strangeness conservation and possibly spin but unsure on this point??

    Please let me know if I'm on the right track here!
     
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