Why masons can be massless but their composite quark and antiquark both massive?

In summary, mesons have mass because they are made of quarks and antiquarks, which have masses. Mesons that have quark masses that are not zero also have non-zero masses.
  • #1
Osiris
20
0
How masons can be massless while their composites quark (q) and antiquark (\bar{q}) are both massive?

Is there any clear physical scenario to understand this?
 
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  • #2
Osiris said:
How masons can be massless while their composites quark (q) and antiquark (\bar{q}) are both massive?

Is there any clear physical scenario to understand this?

Do you mean "mesons"? They are made up of a quark and an antiquark, but they are not massless.
 
  • #3
Sylas is right, mesons actually do have mass. If I remember correctly, the mass is positive, the value being somewhere in-between that of a proton and electron.
 
  • #4
This question is tricky.

If we had a world with exactly massles quarks, then we would have some exactly massless mesons, too. The meson mass zero comes from the fact that these mesons are the so-called Goldstone-bosons of the chiral symmtrey. [the Goldstone theorem says that spontaneous breaking of a continuous symmetry generates massles scalar particles; in case of QCD with massles quarks u,d you would have three massles mesons, namely the familiar pions; in case of QCD with massles quarks u,d,s you would have eight massles mesons, three of them are the familiar pions; ...]

Attention: other particles like vector mesons, nucleon and other stay massive even with massles quarks! Their masses are generated dynamically due to the QCD interaction.

If you now turn on some quark masses to become non-zero, the corresponding Goldstone bososn acquire a small non-zero mass.

Do you know what chiral symmetry of QCD is?
Do you understand the Goldstone theorem?
Do you know what spontanous symmetry breaking means?
 
  • #5
Tom, while what you wrote is correct, it's probably not helpful to be discussing the Nambu-Goldstone theorem to someone who doesn't know that mesons all have mass, or even how to spell mesons. It's true...but probably not the best place to start.
 
  • #6
Maybe you are right - but that's why I am asking questions as well. If Osiris comes back with more basic questions, we can continue, so let's wait and see ...
 
  • #7
Vanadium 50 said:
Tom, while what you wrote is correct, it's probably not helpful to be discussing the Nambu-Goldstone theorem to someone who doesn't know that mesons all have mass, or even how to spell mesons. It's true...but probably not the best place to start.

Vanadium_50 is right. I can add only that apart from knowing 2+2=4, one must know that 2x2=3+1 here.

Bob.
 

1. Why can masons be massless while their composite quark and antiquark are both massive?

Masons, also known as mesons, are subatomic particles composed of a quark and an antiquark. The mass of a particle is determined by the amount of energy it has and the force it takes to accelerate it. In the case of masons, the quark and antiquark are bound together by the strong nuclear force, which is extremely strong but only acts over very short distances. This results in the composite particle having a much higher mass than the individual quark and antiquark. However, the overall mass of the mason can be zero because the strong force also produces a binding energy that can balance out the mass of the quark and antiquark, making the mason appear massless.

2. How can masons be both massless and massive at the same time?

This question often arises because of the dual nature of particles in quantum mechanics. In the quantum world, particles can behave as both a wave and a particle simultaneously. This means that while the overall mass of a mason may be zero, it still has a physical presence and can interact with other particles, giving it a mass-like behavior. This is known as the mass-energy equivalence, as described by Einstein's famous equation E=mc².

3. Are there any other particles that exhibit this phenomenon of being massless while their components are massive?

Yes, there are other particles that follow a similar pattern. For example, the pion, another type of meson, is also composed of a quark and an antiquark and can also have a mass of zero. Additionally, gluons, which are particles that mediate the strong nuclear force, are also massless, but their composite quarks are massive.

4. How do scientists know that masons are actually composed of a quark and an antiquark?

The composition of masons was first proposed by physicist Murray Gell-Mann in the 1960s based on the concept of quark theory. Since then, experiments such as particle accelerators have been used to study the behavior of these particles and provide evidence for their existence. By analyzing the particles produced in these high-energy collisions, scientists have been able to confirm that masons are indeed composed of a quark and an antiquark.

5. Can masons ever be observed in a state where their quark and antiquark are both massless?

No, it is not possible for masons to exist in a state where their quark and antiquark are both massless. This is because the strong nuclear force always produces a binding energy that will contribute to the overall mass of the particle. However, in certain high-energy collisions, it is possible for the binding energy to be large enough to effectively cancel out the mass of the quark and antiquark, resulting in a mason with a very small mass, but it will never be truly massless.

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