Relative Minus Sign for u d -> u d Process?

[dimitronic]

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 Ψ_d)(\bar{Ψ}_dΨ_u)|ud>
process with γ:
<ud|(\bar{Ψ}_u Ψ_u)(\bar{Ψ}_dΨ_d)|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.

 

[Deneen2000]

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.