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Relative minus sign?

  1. Jun 24, 2011 #1
    relative minus sign??

    Hi, I have one question for you...
    to compute the matrix element for the process u d -> u d I want to use full SM, but I have one problem I'll give you the maths.

    process with W:
    <ud|(\bar{Ψ}u Ψd)(\bar{Ψ}dΨu)|ud>
    process with γ:
    <ud|(\bar{Ψ}u Ψu)(\bar{Ψ}dΨd)|ud>
    Z and g are the same with γ (i don't write the propagators and the Lorentz parts for simplicity).
    Is there a minus sign between W and the others??
    I say yes .... but i am not sure.
  2. jcsd
  3. Mar 26, 2017 #2


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    Gold Member

    I just posted this for another post.... I SAY YES also.
    here's the information I found that explains why there is a minus sign.

    rel min sign.jpg
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