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Topological cross section

  1. Dec 1, 2012 #1
    Hello,

    I've found in some of the articles on experimental quantum physics the term "Topological cross section"
    Now I'm trying to understand what is it and in particular what the difference between topological and differential cross section?

    Thanks in advance for suggestions on any reading materials.
     
  2. jcsd
  3. Dec 1, 2012 #2

    Bill_K

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    I believe it means the total cross section for reactions with n outgoing lines.
     
  4. Dec 1, 2012 #3
    I'm not sure if I understand you right. Can you please give me a relationship between total cross section and topological cross section.
     
  5. Dec 1, 2012 #4

    Bill_K

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    From what I gather, the total cross section σ is the sum over n of the topological cross sections σn. Again, σn is the total cross section (i.e. integrated over angles) of all reactions with n outgoing lines. It looks like they count only visible (charged) lines and/or just the ones that exceed a given momentum.
     
  6. Dec 2, 2012 #5
    May be it is just another word used,because in drawing feynman diagrams one use only those diagrams which are topologically different.
     
  7. Dec 2, 2012 #6

    Bill_K

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    :confused: Every Feynman diagram is topologically different. And every process comes from an infinite number of different Feynman diagrams.
     
  8. Dec 2, 2012 #7
    Do you find contradication between these two statements?
     
  9. Dec 2, 2012 #8
    Well, your guess about counting only charged particles I can understand, but counting only ones that exceed any given momentum can't be true. In this case the value of this cross section would greatly depend on which momentum they will take.
     
    Last edited: Dec 2, 2012
  10. Dec 2, 2012 #9
    I think it's not that simple. "digitool.library.mcgill.ca/thesisfile74351.pdf" [Broken] I found the following definition of this term:
    Thought I didn't understand it yet. :smile:
     
    Last edited by a moderator: May 6, 2017
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