All Questions
Tagged with quantum-chromodynamics color-charge
68
questions
2
votes
1
answer
91
views
How is the colour quantum number not conserved in this process?
I stumbled upon this CERN article, where I found this diagram describing the process $gg \rightarrow HH$:
I'm still new to QCD, and I don't see how a coloured gluon can decay into colourless final ...
2
votes
1
answer
183
views
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
400
views
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
2
votes
2
answers
254
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Can mesons be in $b \overline{b}$, $r \overline{r}$, $g \overline{g}$ states?
Can a meson be in a pure $b \overline{b}$, $r \overline{r}$, $g \overline{g}$ state or does it have to be in the $\frac{1}{\sqrt{3}}\left(b \overline{b}+r \overline{r}+g \overline{g}\right)$ state?
...
- 631
2
votes
2
answers
514
views
Eight gluons, what are the properties of two of them?
If there are 8 gluons, and 6 of them can be represented as a color/anticolor pair (red/antiblue for example), that leaves 2 "other" gluons. How do these two gluons differ from each other? ...
- 51
2
votes
0
answers
245
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Bern-Carrasco-Johansson (BCJ) Double Copy and Color-Kinematic duality
According to the wikipedia page on Strong Gravity, the theory is considered "non-mainstream", but from what I can gather there have been some very interesting progress and results since it ...
- 14.5k
4
votes
1
answer
313
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Understanding the proof of the "Photon-Decoupling Identity" for colour-ordered Yang-Mills amplitudes
Problem:
To prove the Photon-Decoupling Identity for colour-ordered Yang-Mills amplitudes:
$$0= A(1,2,3,...,n)+A(2,1,3,...,n)+...+A(2,3,...,1,n) \tag{1}$$
I know I must use $(2)$, which expresses ...
- 753
2
votes
0
answers
550
views
Colour-ordering formula of QCD amplitudes (tree-level)
I have been studying colour-ordered amplitudes and spinor helicity formalism for a while. It is now apparent to me that I do not fully understand the 'master' formula which allows us to relate the ...
- 155
0
votes
0
answers
68
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Why there is no such a thing as colour moment?
I was busy google about different types of electric and magnetic dipole moment then a thought suddenly striked me, why there is no colour multipole moment?
- 13k
1
vote
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
4
votes
1
answer
874
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How are quarks assigned color charge?
As always, I'll preface that I am wildly undereducated, so i may be overlooking something or be completely unaware of another relevant property.
Color Confinement dictates that to "assemble" a baryon ...
- 481
3
votes
2
answers
2k
views
Confusions with gluons. How many of them are there?
Gluons are bicolored objects. They are made out of one color and one anticolor. Therefore, there seems to be nine possible states $r\bar{r},r\bar{b},r\bar{g},b\bar{r},b\bar{b},b\bar{g},g\bar{r},g\bar{...
- 11.8k
1
vote
0
answers
70
views
Why use $SU(3)$ and not $SL(3, \mathbb{R})$ for color charge? [duplicate]
Why do we use the group $SU(3)$ and not $SL(3, \mathbb{R})$ for color charge?
As far as I can tell, the $SL(3, \mathbb{R})$ is volume and orientation preserving, by the fact that it has unit ...
- 161
0
votes
1
answer
475
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Why don't green and anti-green gluons immediately annihilate each other?
I can't believe I haven't found an answer elsewhere.....
I have read repeatedly about blue/anti-blue gluons, etc., but no reason as to why they don't destroy each other immediately.....
Or maybe they ...
- 4,509
1
vote
2
answers
514
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Color symmetries in variant QCD
Suppose we only have two colors, for example, red (R) and blue (B) to construct the wave functions of baryons and mesons and that the color symmetry is SU (2) and not SU (3). In this situation, ...
