# Gluon-Gluon Four-point vertex

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simplemind
Hello,

First,i am an absolute beginner in QCD.

As i have seen there are six different Feynmangraphs for the Four-Point vertex.
Swordfish,Box,...

I am interested in the first of the six where the two gluons met in a point and goes away.
My question now is.
If for this case two different charged Gluons interact are they repulsive?

and take a look on the picture on (5.14)

I am interested in the action of the first of the three posibilities the cross and not the lines.

Last edited:

Staff Emeritus
i am an absolute beginner in CCD
I think you mean QCD.

first of the six
There is no standard counting. "First" does not specify.

If for this case

You can't get a physical quantity by calculating one diagram (it likely won't even be finite). You need to calculate the sum of all diagrams that contribute to a process.

simplemind
Thanks but i only want to know if the first component acts repulsive or not.
From the sign it is different to the two negative others.
I think it is possible to anwer.

Mentor
i only want to know if the first component acts repulsive or not
And this is a meaningless question because, as @Vanadium 50 said, you have to look at all diagrams for a given process together; just looking at one tells you nothing. So it doesn't even make sense to ask if just one diagram "acts repulsive"; just one diagram by itself is physically meaningless.

simplemind
Thanks but i am interested in it.Maybe it is meaningless in this case.
All diagrams are also interesting but as i said i am interested in the first component.
The background is that diagram 2 and 3 have a gluon between and diagram 1 not!
So i assume that the first diagram has repulsive results wenn the charge of the gluons is different.
For diagram 2 and 3 i think it is attracitve for different charged gluons (other sign as component 1 ) because there is a spin 1 gluon between.
Maybe i am completely wrong because i am a beginner.
I still think that it is possible to give an answer.

weirdoguy
Mentor
Maybe i am completely wrong because i am a beginner.
If you think you are asking a meaningful question that can be answered, yes, you are wrong.

I still think that it is possible to give an answer.
Unfortunately it is not, for reasons that have already been explained.