ONLY three quark colors (and three anti-colors)?

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In summary: Higgs is a composite state of a new strongly coupled sector.In summary, the Standard Model prohibits the existence of more than three colors of quarks, and the theory of color charge was developed to explain experimental results and maintain consistency in the model. However, there are extensions such as technicolor models that introduce new quantum numbers and forces.
  • #1
jerich1000
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I realize that because of the Pauli exclusion principle, two identical quarks (such as two up quarks in a proton) cannot occupy the same space, hence the variations in color provided by qluon interaction.

I have two questions:

Can "color" be thought of as a state, such a light switch can be on or off? And thus, there is no physical difference between a red, green, or blue quark (I realize those terms are allegorical), because the "red" one and instant later will be the "green" one, etc.

The next question is this: Must there only be three colors of quarks (and three anti-colors)? Does the Standard Model PROHIBIT more than three colors? Or is it that only three colors are necessary and that there is only evidence of thre colors so far?

Thanks
 
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  • #2
jerich1000 said:
I realize that because of the Pauli exclusion principle, two identical quarks (such as two up quarks in a proton) cannot occupy the same space, hence the variations in color provided by qluon interaction.

I have two questions:

Can "color" be thought of as a state, such a light switch can be on or off? And thus, there is no physical difference between a red, green, or blue quark (I realize those terms are allegorical), because the "red" one and instant later will be the "green" one, etc.

The next question is this: Must there only be three colors of quarks (and three anti-colors)? Does the Standard Model PROHIBIT more than three colors? Or is it that only three colors are necessary and that there is only evidence of thre colors so far?

Thanks

I am getting out of my area of expertise here, but I believe the answer to your question is that, according to the standard model and the theory of quantum chromodynamics, there are EXACTLY 3 colors (and their corresponding anti-colors). This is because the theory of color charge was developed to explain the observed experimental results, which suggested an underlying fundamental symmetry that transformed as the SU(3) group. (For reference, spin transforms as SU(2) group, as does isospin, which is another property of nucleons.)

Thus, I *THINK* the answer is that, if experiments suggested there was another kind of color charge, it would mean that the Standard Model was in serious trouble ...
 
  • #3
You mentioned one reason - color is necessary to properly fit three quarks having Fermi-Dirac statistics together to form a nucleon. Another reason is the anomaly cancellation, which for consistency requires the sum of charges of the particles in a fermion generation to be zero. This only works if the quarks are counted with a weighting factor of 3 because they are really three different particles:

3(2/3) + 3(-1/3) + (-1) + 0 = 0.
 
  • #4
The next question is this: Must there only be three colors of quarks (and three anti-colors)? Does the Standard Model PROHIBIT more than three colors? Or is it that only three colors are necessary and that there is only evidence of thre colors so far?
Yes, the Standard Model prohibits the existence of more than 3 colors. Prohibits by definition, since it explicitly states that that there are 3 of them, period.

However, there are extensions of Standard Model that assume more than 3 colors and these are called "technicolor" models.
 
  • #5
There are two different perspectives:

First there is a pure algebraic perspective where one attributes spin, color and flavor (up, down, strange, ...) to a quark.

Later one discovered QCD which adds a dynamical perspecive where gluons couple to a color-current density just like photons couple to electric-current density.
 
  • #6
However, there are extensions of Standard Model that assume more than 3 colors and these are called "technicolor" models
The technicolor in technicolor models are not "more colors", they're an entirely new quantum number characterizing an entirely new force.
 
  • #7
exactly, technicolor means essentially

spin, color (rgb) and flavor (up, down, strange, ...), technicolor (...)
 

FAQ: ONLY three quark colors (and three anti-colors)?

1. What are quark colors and anti-colors?

Quark colors and anti-colors are properties that describe the strong nuclear force interaction between quarks. There are three colors - red, green, and blue - and three anti-colors - anti-red, anti-green, and anti-blue.

2. Why are there only three quark colors and three anti-colors?

This is due to the fundamental symmetry of the strong nuclear force, known as SU(3) symmetry. This symmetry predicts that there can only be three colors and three anti-colors.

3. What is the significance of quark colors and anti-colors in the Standard Model?

The Standard Model is a theory that describes the fundamental particles and forces in the universe. Quark colors and anti-colors are an essential part of the model as they explain how quarks interact with each other through the strong nuclear force.

4. Are there any particles that do not have quark colors?

Yes, there are particles called leptons that do not have quark colors. Leptons are fundamental particles that do not interact through the strong nuclear force and include particles like electrons and neutrinos.

5. How do quark colors and anti-colors combine to form composite particles?

Quarks with different colors can combine to form composite particles, such as protons and neutrons. In these particles, the three quark colors cancel each other out, resulting in a colorless state. Similarly, anti-quarks with different anti-colors can combine to form anti-particles.

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