Why are gluons considered to be elementary particles?

In summary, gluons are often thought of as fundamental particles in the Standard Model, but they are actually mesons - composite quark-antiquark pairs that act as gauge bosons due to their spin being zero. However, the weak force W bosons cannot be depicted as mesons. The Standard Model particles include vector bosons, scalar bosons, and fermions. Mesons are not fundamental particles, as they have mass and other properties that differ from gluons. The use of mesons as force carriers for inter-hadron interactions is not the same as the quantum state of gluons.
  • #1
Sophrosyne
128
21
Gluons are often depicted as fundamental particles in the Standard Model. But in looking at their mechanism, it seems they are not really fundamental particles in the sense that they are fundamental, indivisible, building blocks. They are mesons- a composite quark-antiquark pair, where their spin adds up to zero and therefore they act as gauge bosons.

And speaking of that, it seems even the weak force, the W bosons, can also be depicted equivalently as mesons, can't they?

Am I misunderstanding this somehow?
 
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  • #2
Sophrosyne said:
They are mesons- a composite quark-antiquark pair
They are not. Mesons have mass, mesons are color-neutral, mesons have excited states, and various other properties that differ from gluons.
Sophrosyne said:
And speaking of that, it seems even the weak force, the W bosons, can also be depicted equivalently as mesons, can't they?
It cannot.
 
  • #3
Sophrosyne said:
They are mesons- a composite quark-antiquark pair, where their spin adds up to zero and therefore they act as gauge bosons.
where did you get that information?
The Standard Model particles are the following:
Vector Bosons (Spin=1) : W/Z-bosons [W/Z], photons [γ], gluons [g]
Scalar Boson (Spin = 0) : Higgs [H]
Fermions (Spin=1/2):
__leptons don't interact via strong interactions:
electron (e), muon (μ), tau (τ) and the respective neutrinos (νe,μ,τ)
__quarks do interact via strong interactions:
up (u), down (d), charm (c), strange (s) , top (t) , bottom (b)
 
  • #4
I see. I guess I was seeing the use of mesons as force carriers for the inter-hadron interactions, and I also saw that gluons carry color charge in eight different types even for the inter-quark interactions, represented by the "color octet" states. These are represented in a quark-antiquark representation, and thought that was the same thing as a meson. But that just seems to be the quantum state of the gluon, not a meson.
 
  • #5
The quark-antiquark colour representation is a 9-dimensional representation (since it is the product of two 3-dimensional ones). It can be split into a colour singlet, which is the colourless trivial representation of mesons, and a colour octet - the same representation that the gluons transform according to.
 

1. What are gluons and why are they considered elementary particles?

Gluons are subatomic particles that mediate the strong nuclear force, which is responsible for holding the nucleus of an atom together. They are considered elementary particles because they cannot be broken down into smaller components and have no known substructure.

2. How do gluons interact with other particles?

Gluons interact with other particles through the strong nuclear force. They carry a color charge (red, green, or blue) and can exchange this charge with quarks, which also carry color charge. This interaction keeps quarks bound together inside protons and neutrons.

3. Why are gluons important in the Standard Model of particle physics?

Gluons are an essential part of the Standard Model, which is the most widely accepted theory explaining the fundamental particles and forces in the universe. They play a crucial role in the strong nuclear force, one of the four fundamental forces, and their properties are well-described by the Standard Model.

4. Can gluons exist independently?

No, gluons cannot exist independently because they are always found in combination with other particles. The strong nuclear force is so strong that it is impossible to separate gluons from the particles they bind together. They are always exchanged between particles during interactions.

5. Are there any experiments or evidence that support the existence of gluons?

Yes, there is strong experimental evidence for the existence of gluons. For example, high-energy particle collisions at the Large Hadron Collider have produced evidence of gluon interactions and their effects on other particles. Additionally, the successful predictions of the Standard Model, which includes gluons, provide strong evidence for their existence.

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