Undergrad Are Different Charged Gluons Repulsive in the Gluon-Gluon Four-Point Vertex?

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The discussion centers on the interaction of different charged gluons in Quantum Chromodynamics (QCD), specifically regarding the Four-Point vertex and its Feynman diagrams. The original poster seeks to understand if the first diagram, where two gluons meet at a point, exhibits repulsive behavior when the gluons have different charges. However, responses indicate that analyzing a single diagram is insufficient for determining physical interactions, as all contributing diagrams must be considered collectively. The conversation concludes with the assertion that the question posed lacks meaningfulness due to its focus on an isolated diagram. Ultimately, the thread is closed without a definitive answer to the original inquiry.
simplemind
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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?

I am reading

https://link.springer.com/article/10.1140/epjc/s10052-020-8260-8

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.
 
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simplemind said:
i am an absolute beginner in CCD
I think you mean QCD.

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

simplemind said:
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.
 
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.
 
simplemind said:
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.
 
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.
 
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simplemind said:
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.

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

Thread closed.
 
Insights auto threads is broken atm, so I'm manually creating these for new Insight articles. Towards the end of the first lecture for the Qiskit Global Summer School 2025, Foundations of Quantum Mechanics, Olivia Lanes (Global Lead, Content and Education IBM) stated... Source: https://www.physicsforums.com/insights/quantum-entanglement-is-a-kinematic-fact-not-a-dynamical-effect/ by @RUTA

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