All Questions
18
questions
1
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1
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77
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Justifying the identification of eight gluons with the ${\bf 8}$ from ${\bf 3}\otimes{\bf 3}^*$
When we combine the fundamental ${\bf 3}$ and antifundamental ${\bf 3}^*$ of color $SU(3)$ of QCD i.e. single quark of three colors and a single antiquark of 3 anticolors, nine states are obtained. ...
- 11.8k
3
votes
1
answer
292
views
Why $\pi^+$ meson possible combinations of quarks is only three?
I am a starter at nuclear and particles physics. I am reading particles and nuclei an introduction to the physical concepts. There was a paragraph about Colour-neutral particles and how only ...
- 176
0
votes
2
answers
91
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Quantum chromodynamics - why are there no $rrb$ or $ggr$ terms?
$$\Psi_{colour}^{qqq} = \frac{1}{\sqrt{6}}(rgb + gbr + brg -grb - rbg - bgr)$$
My lecturer stated that there cannot be any $rrb$ or $ggr$ terms in the expression above. I would like to understand what ...
- 13
-1
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1
answer
129
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A gluon can have nine independent, bicolored states. How are some of the additions of these individual states, like $r\bar{r}+g\bar{g}+b\bar{b}$?
This came from the 25th page of the following pdf: http://www.gammaexplorer.com/wp-content/uploads/2014/03/Quarks-and-Leptons-An-Introductory-Course-in-Modern-Particle-Physics.pdf
Sorry if I am asking ...
2
votes
1
answer
183
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Why is the $SU(4)$ group not suitable for describing color symmetry?
How to demonstrate that the $SU(4)$ group cannot be a group of symmetry of a color charge?
6
votes
3
answers
401
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Do hadrons have color moments?
Hadrons have electrical moments since they are made up of both positive and negative charges. Water molecules have dipole moments for the same reason even though they are electrically neutral.
Since ...
- 639
1
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1
answer
463
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What's the definition of $\bar\psi$ in QCD?
This is a two part question.
What is the definition of $\bar\psi$ in QCD?
In QED I know that $\bar\psi=\psi^\dagger\gamma^0$, but in QCD we also have flavor and/or color space. In particular, I'm ...
- 3,407
1
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3
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2k
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Why do quarks and gluons have colour?
I asked a question here a few days ago and got some fantastic answers so I'm going to continue.
Let me preface this by saying I know quarks do not actually have 'colour', but colour is some sort of ...
- 311
0
votes
2
answers
333
views
Can the three quark colors be considered to correspond to different particles?
Is it harmless to count three, say, up quark particles instead of one up quark with three colors, as well as 8 different gluons instead of one with different color?
3
votes
1
answer
177
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Is it possible different coloured quarks have slightly different masses?
For example, could the red-down-quark have a slightly different mass to the red-up-quark?
Since quarks rest masses are so much lighter than the particles they make up, that little bit of different ...
user84158
4
votes
1
answer
2k
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$SU(3)$ Color Symmetry
I have following (maybe a bit general) question about the $SU(3)$-symmetry of color by quarks:
If I consider the analogy to the $SU(2)$-symmetry of isospin $I$ crucially it concers the conservation ...
- 1,395
1
vote
2
answers
502
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Quark jet color
When a 2-jet event occurs due to a quark + antiquark emerging back-to-back, the jets ultimately decay to stable particles. Each jet starts with a quark (or antiquark) carrying a color and ends as a ...
- 12.7k
26
votes
3
answers
5k
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How (or when) do gluons change the color of a quark?
I know a baryon is only stable when it contains a quark of each color. And as far as I know, the gluon essentially changes the color of a quark and moves onto the next, and this is what holds the ...
- 508
0
votes
2
answers
1k
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Why are 3 colors used in QCD?
The mapping of strong charge to RGB left me believing that there are only 3 conserved quantities in QCD. I recently came to the understanding that there are in fact 8 conserved quantities, as ...
- 403
4
votes
3
answers
916
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How does quark color affect the identity of a hadron?
I've read about colors relating to quarks and hadrons and I know that they can change colors because of the exchange with gluons, but does changing color change the type of hadron? Does a proton ...
