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A Relative sign in diagrams for ##Z##-boson exchange for ##WW## scattering

  1. Mar 26, 2017 #1
    Consider the scattering process ##W^{+}W^{-} \to W^{+}W^{-}##. This process is mediated in the Standard Model by

    1. a four-##W## scattering,
    2. ##Z##-boson exchange,
    3. Higgs exchange.

    ------------------------------------------------------------------------------------------------------------------------------

    Let us consider the diagrams for ##Z##-boson exchange:

    82a12c3798.png


    Why is there a relative minus sign between the matrix elements for the two diagrams?
     
  2. jcsd
  3. Mar 26, 2017 #2

    Deneen2000

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    Newbie here...have you considered that the relative minus sign btwn two terms is dictated by the Fermi-Dirac stats? something about a possible closed loop - which carries the extra minus sign.

    I hope this helps.

    Deneen
     
  4. Mar 26, 2017 #3
    Could you be more specific?
     
  5. Mar 26, 2017 #4

    Deneen2000

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  6. Mar 27, 2017 #5

    ChrisVer

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    how can you use Fermi-Dirac statistics for W/Z bosons?
    Also I think that that minus sign mentioned in your reference appears between t- and u- channels...
     
    Last edited: Mar 27, 2017
  7. Mar 27, 2017 #6

    CAF123

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    @spaghetti3451 Could you explain why you think there should be a relative minus in the first place for this process? There is no u channel process here in the case of a Z mediator.
     
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