Is baryon antisymmetry always true?

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In summary: The wavefunction for a baryon must be antisymmetric in order to satisfy the PEP. This is because the baryon has three quarks, and as long as all three are different, the wavefunction is antisymmetric. If the quark flavors were the same, then the wavefunction would not be antisymmetric, and the PEP would not be satisfied.
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CAF123
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The baryon wavefunction is comprised of the direct product of contributions forming different Hilbert spaces such that $$|\Psi \rangle = |\text{spin} \rangle \otimes |\text{flavour}\rangle \otimes | \text{colour}\rangle \otimes |\text{space}\rangle. $$ The necessity for a colour degree of freedom is usually motivated in the literature from the delta(++) spin 3/2 containing quark content ##uuu##. It is flavour symmetric by inspection, is symmetric in the spin quantum numbers and for lowest lying states, has symmetric space state. The state thus contains identical fermions but is overall symmetric under interchange of any of the quarks. This is in violation of the PEP – the resolution was of course the addition of the colour degree of freedom which is necessarily antisymmetric so as to conform to the principle.

It’s then said that the generic wavefunction for a baryon is overall antisymmetric. Is this only the case where the baryon wavefunction is of the form ##\epsilon_{ijk} \psi^{(1)}_i \psi^{(1)}_j \psi^{(1)}_k## or ##\epsilon_{ijk} \psi^{(1)}_i \psi^{(1)}_j \psi^{(2)}_k## where in the former case we have all three qqq the same and in the latter only two are identical?

I say this because if we consider one of the baryons with no flavour symmetry e.g ##|uds \rangle## this is a state with no identical fermions so does the the PEP (i.e total wavefunction antisymmetry) have to hold for this case? (I guess analogously to the fact that the mesons have no requirement of antisymmetry because the content of the valence quarks is ##q \bar q## and this is never two identical quarks)
 
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You have the color degrees of freedom for every baryon, but if the quark flavors are different, you don't have to worry about exchanges of quarks. The "exchange of color" is still relevant (there is nothing special about "green", for example).
 
  • #3
Yes, but does baryonic states with no flavour symmetry of the quarks have to obey Fermi-Dirac statistics? Just by looking at the flavour content of such states we see that it is not possible to have any two identical quarks and so the requirement of PEP/Fermi-Dirac statistics/antisymmetry of wave function perhaps need not be obeyed by such configurations?
 
  • #4
All the up quarks in an uds baryon follow the Fermi-Dirac statistics. For a single quark that is not a really interesting property.
 
  • #5
The observable 'uds' states are in a flavour symmetric combination (the 10), flavour antisymmetric (the 1), and two mixed flavour symmetries (the two 8's) - so the observable states are either all antisymmetric or symmetric in flavour. But for the case of uds quark content we can never have any two of of u,d or s in the same quantum state. So why do we still say that the baryon wavefunction for these states still has to satisfy Fermi-Dirac stats? The states with u,d and s quark content do not have identical particles so why do we still say that they have to have an overall wavefunction satisfying antisymmetry? (I'm just trying to understand why the PEP/Fermi dirac stats should be enforced on such states)
 

1. What is baryon antisymmetry?

Baryon antisymmetry is a principle in particle physics that states that all baryons (particles composed of three quarks) must have a unique combination of quark flavors, regardless of their spin or other properties. This means that no two baryons can have the same exact combination of quarks.

2. Why is baryon antisymmetry important?

Baryon antisymmetry is important because it helps to explain the observed stability of matter and the existence of different types of baryons. It also plays a key role in the development of theories such as the Standard Model, which describes the fundamental particles and forces in the universe.

3. Is baryon antisymmetry always true?

While baryon antisymmetry is generally accepted as a fundamental principle in particle physics, there are some rare exceptions. For example, certain types of exotic particles, such as pentaquarks, may not follow this principle. However, baryon antisymmetry is still considered to be a valid principle in the vast majority of cases.

4. How is baryon antisymmetry tested?

Baryon antisymmetry can be tested through various experiments and observations. For example, scientists can study the properties of different types of baryons, such as their mass, charge, and decay patterns, to see if they follow the principle of baryon antisymmetry. Additionally, high-energy particle colliders can be used to create and study rare particles that may not follow this principle.

5. What are the implications of baryon antisymmetry for our understanding of the universe?

Baryon antisymmetry is an important aspect of our current understanding of the universe and its fundamental particles. It helps to explain why certain types of matter exist and provides a framework for studying the behavior of particles and their interactions. By studying baryon antisymmetry, scientists can gain a better understanding of the fundamental forces and building blocks of the universe.

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