All Questions
Tagged with quantum-chromodynamics quantum-mechanics
31
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Colour Factor in QCD Pair Annihilation
My question occurred when I was reading Introduction to Elementary Particles by David J. Griffiths. In chapter 8, part 8.5, he is calculating the colour factor of quark-antiquark annihilation.
My ...
- 81
-1
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2
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205
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How exactly does a proton form from quarks? What is the exact sequence and mechanism?
What are the steps that lead to the bonding of two up quarks and one down quark into a proton? For instance, does an up quark "bind" with a down quark in quark-gluon plasma, which then binds ...
- 29
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Diquark propagators in color superconductivity
I’m studying color superconductivity referring to “The Phases of Quantum Chromodynamics From Confinement to Extreme Environments” by John B. Kogut and Mikhail A. Stephanov (link).
In chapter 9, the ...
- 165
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Are all mass eigenstates also spin eigenstates?
Is there a rigorous way to show that a mass eigenstate of a particle must also be an eigenstate of the total spin operator? If this wasn't true, you could imagine that a composite particle in a mass ...
- 867
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28
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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
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89
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Color factor in Breit-Wigner formula
We are given the Breit-Wigner formula for the process $ud\rightarrow W\rightarrow e\nu$ as $$\sigma=\frac{1}{N_c^2}\frac{2J_W+1}{(2J_u+1)(2J_d+1)}\frac{4\pi}{s}\frac{\Gamma_{ud}\Gamma_{e\nu}}{(\sqrt{s}...
- 2,122
3
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555
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How exactly do quarks suppress gluon fluctuations?
In both this Veritasium Video and this answer it is said that Quarks suppress gluon fluctuations, thus creating a so-called 'flux tube' which is what binds the gluons together (as explained in both ...
- 3,778
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What happens to an electron when it radiates a photon?
I recently came across this Feynman diagram:
For a more simplistic diagram, I suppose even this would be adequate:
As you can see in these diagrams, they radiate these virtual photons. The virtual ...
- 126
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What is the real problem in the free body problem?
Ions are produced when an EM neutral atom gains EM charge by gaining or losing electrons, by collision with other charged particles or photons.
The study of such collisions is of fundamental ...
- 29k
2
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1
answer
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Quark-Gluon Plasma vs QCD binding energy
The binding energy of nucleons is on the order of around 900 MEV. Yet, Quark-Gluon plasma is observed at around 175-300MEV. This doesn't seem to make any sense - how can only 300 MEV worth of energy ...
- 545
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160
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Why are gluons necessary?
I understand that quarks are attracted to each other when they have different color charges to become neutral. I also understand that gluons are the exchange particles of the strong force by switching ...
2
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1
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725
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What's a "colour triplet fermion"?
I'm not a big fan of Science Alert, but this recent piece about the so-called SMASH model, whose gory details are apparently presented in arXiv:1608.05414 seems reasonable. I'm curious about this "...
- 134k
4
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1
answer
1k
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Callan-Gross relation validity
The inelastic electron-proton scattering cross section can be written as
$$\frac{d\sigma}{dE_2d\Omega}=\frac{\alpha^2}{4*E_1\sin^4{\frac{\theta}{2}}}(W_2\cos^2{{\frac{\theta}{2}}}+2W_1\sin^2{{\frac{\...
- 263
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2
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Can quarks have anti-colors? [closed]
What is the reason that the color properties we call red, green and blue have become tied to quarks, while what we call anti-red, anti-green and anti-blue has become tied to anti-quarks? Do note that ...
- 415
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What is a "dynamically generated scale" physically?
A theory like QCD with massless quarks in four dimensions has no explicit mass parameters in its classical Lagrangian. At the quantum level however, instead a mass scale Λ is generated dynamically at
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