All Questions
Tagged with quantum-chromodynamics standard-model
155
questions
0
votes
1
answer
129
views
Can a gluon split into three gluons: $g \rightarrow ggg$? (four gluon vertex)
I know $gg \rightarrow gg$ is possible, but is $g \rightarrow ggg$ possible? I don't see this anywhere although I think you could conserve colour charge (e.g. $r\bar{g} \rightarrow r\bar{g} + g\bar{b}...
- 351
0
votes
1
answer
185
views
Is $SU(3)$ (and not $U(3)$) the symmetry group of color interactions because $U(1)$ is already used for EM?
I have already seen this question. It was answered that $U(3)$ can be decomposed into $SU(3) \times U(1)$, and $U(1)$ is already used for the EM interaction. Still, I wonder why the EM interaction ...
1
vote
0
answers
28
views
Correlation of the strong force with fractional charges? [duplicate]
As far as we know the quarks are not free not because of their fractional charges but because of the independent strong force interaction that grows with distance within the radius of the proton or ...
- 4,170
0
votes
1
answer
454
views
Hadronization time
In the process of hadronization what is the characteristic time? I was thinking about at the inverse of $\Lambda_{\rm QCD}$ but can also be a dependence from $\sqrt{s}$. Can anyone help me?
- 496
7
votes
1
answer
976
views
Do gluons care about flavor?
I think the answer to my question is no, but I can't find an explicit statement about this on my books or online.
I know that gluons are the vector bosons for QCD, the $SU(3)$ gauge theory of color, ...
- 5,931
2
votes
1
answer
358
views
Does "lifetime of up quark" have a physical meaning?
I saw this question about the lifetime of an up quark.
As far as I know, free quarks are never observed in experiments. Then what is the significance of a statement like "the lifetime of an up ...
- 3,160
2
votes
2
answers
68
views
How do we understand the ${\bf 3}$ of $Q_L({\bf 3}, {\bf 2})_{1/3}$?
A left-handed quark doublet of the Standard Model is specified as $Q_L({\bf 3}, {\bf 2})_{1/3}=(u,d)^T$. I have a problem understanding this quark doublet as a triplet of ${\rm SU}(3)$. Any help? I ...
- 11.8k
14
votes
5
answers
2k
views
Why aren't all quarks clumped together in one giant hadron?
As far as I am aware, the strong interaction is attractive only, and its carrier, the gluon, is massless meaning it has unlimited range. If this is the case, how come we only observe quarks in pairs ...
- 451
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 ...
1
vote
0
answers
63
views
Can the process gluon + gluon $\rightarrow$ 2 Higgs proceed in the following way in the standard model?
At order $g_s^2$, usually only a triangle quark loop and box diagram are considered, I was wondering, is there some reason that excludes these diagrams from the possible standard model channels?
2
votes
0
answers
84
views
How many extra dimensions needed to model the Strong interaction with a Kaluza-Klein extended theory?
The blog / video (See: https://backreaction.blogspot.com/2021/04/does-universe-have-higher-dimensions.html - Does the Universe have Higher Dimensions? Sabine Hossenfelder's blog) is discussing the ...
- 61
2
votes
2
answers
288
views
Do the “$SU(3)$ colors” live in a 3-dimensional vector space?
Previously I asked a question about the visualized colors:
Do the "colors" live in a 3-dimensional vector space?
(My earlier question is unfortunately closed)
Now I like to ask the “$SU(3)$ ...
- 4,336
3
votes
2
answers
689
views
What is "Colombia Plot" in reference to lattice QCD?
In High Energy Physics papers, I often see a diagram as shown below:
I am still studying Quantum Field Theory, and I could not understand the only reference I could find about this plot: https://...
0
votes
0
answers
83
views
How does the electroweak interaction and QCD form $SU(2)$ and $SU(3)$?
I'm trying to get a foothold into quantum field theory from a mathematical background. I see the use of $SU(2)$ and $SU(3)$ in gauge theory and wonder the following questions to help me bring QFT ...
- 101
1
vote
2
answers
30
views
Understanding Jet Clustering: Why is only $p_{T}$ used?
Let's only consider iterative jet clustering algorithms. Famous ones are the $k_{T}$ ($p = 1$), anti-$k_{T}$ ($p = -1$) and Cambridge/Aachen ($p = 0$) jet reconstruction algorithms.
All these ...
user248824