All Questions
Tagged with quantum-chromodynamics color-charge
68
questions
29
votes
1
answer
7k
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Mathematically, what is color charge?
A similar question was asked here, but the answer didn't address the following, at least not in a way that I could understand.
Electric charge is simple - it's just a real scalar quantity. Ignoring ...
- 1,505
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
16
votes
2
answers
3k
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Why doesn't the color force between two quarks have an inverse square law?
From what I understand the color force between two quarks doesn't decrease with distance. Why is it that the color force doesn't decrease with the square of the distance if there are three dimensions ...
- 2,001
16
votes
2
answers
10k
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What IS Color Charge?
This question has been asked twice already, with very detailed answers. After reading those answers, I am left with one more question: what is color charge?
It has nothing to do with colored light, ...
- 281
13
votes
1
answer
480
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Could the universe have non-vanishing net colour charge?
I've heard that the strong force doesn't decrease in strength with increasing distance, and that's why quarks must be confined within hadrons. But could there be, say, a single quark out there, so ...
- 6,601
12
votes
3
answers
4k
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Why is color conserved in QCD?
According to Noether's theorem, global invariance under $SU(N)$ leads to $N^2-1$ conserved charges. But in QCD gluons are not conserved; color is. There are N colors, not $N^2-1$ colors. Am I ...
- 7,398
9
votes
1
answer
2k
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Is there an explanation for the 3:2:1 ratio between the electron, up and down quark electric charges?
I understand that the NNG formula relates $Q$, $I_3$, and $Y$ and can be derived in QCD; does this unambiguously predict the electric charge ratios without making assumptions about the definitions of ...
- 7,398
9
votes
1
answer
386
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Are mesons color polarized?
The binding of quarks in mesons baffles me. It's an Occam's Razor thing.
Since a meson is a colorless, the simplest way to bind its two quarks together is to use a $U(1)$ Cartan subalgebra of $SU(3)$. ...
- 22.1k
8
votes
1
answer
1k
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Does the color of a quark matter in a meson?
QCD and confinement specify that hadrons must be color-neutral. My understanding is that this means you can have mesons (quark + antiquark) or baryons with 3 quarks, one of each color: Red+green+blue=...
- 1,484
7
votes
1
answer
3k
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How to sum over final, and average over initial color states?
Consider the $s$-channel mediated top quark production process
$$ d + \overline d \rightarrow t + \overline t$$
Using the Feynman rules for QCD, the amplitude contains a color factor
$$[c^\dagger _{\...
6
votes
3
answers
401
views
Do hadrons have color moments?
Hadrons have electrical moments since they are made up of both positive and negative charges. Water molecules have dipole moments for the same reason even though they are electrically neutral.
Since ...
- 639
5
votes
1
answer
1k
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Permissible combinations of colour states for gluons
My lecturer has said that there are 8 types of gluons (I'm assuming that the repetition of $r\bar{b}$ is a typo that is meant to be $r\bar{g}$)
$$r\bar{b}, b\bar{r}, r\bar{g}, g\bar{r}, g\bar{b}, b\...
- 205
5
votes
1
answer
672
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Group theoretical reason that Gluons carry color-charge and anti-colorcharge
I was wondering how it is possible to see from the $SU(3)$ Gauge Theory alone that Gluons carry two charges colors: $g\overline{b}$ etc.
Some background:
The W-Bosons (pre-symmetry breaking) form an ...
- 10.1k
5
votes
1
answer
185
views
Would Color Confinement apply in higher dimensions?
As I understand it color confinement comes from the fact that as the distance between two color charges increases the color potential energy increases, instead of decreasing, and the energy needed to ...
- 2,001
4
votes
3
answers
1k
views
Is the concept of bicolored gluons mathematically precise/meaningful? Please explain
Each flavour of quark carries a colour quantum number: red, green or blue. I know what it means mathematically. But elementary textbooks (e.g, particle physics by Griffiths) also say that gluons are ...
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