Is baryon antisymmetry always true?

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Discussion Overview

The discussion revolves around the antisymmetry of baryon wavefunctions, particularly in the context of the Pauli exclusion principle (PEP) and the implications of quark flavor symmetry. Participants explore whether baryons composed of different flavors, such as the uds baryon, must adhere to antisymmetry requirements due to the indistinguishable nature of fermions.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Technical explanation

Main Points Raised

  • One participant describes the baryon wavefunction as a product of different Hilbert space contributions and questions whether the overall antisymmetry requirement applies when considering baryons with non-identical quark flavors.
  • Another participant notes that while color degrees of freedom are present, the lack of identical quark flavors means that exchanges of quarks may not necessitate antisymmetry.
  • A different viewpoint suggests that baryonic states without flavor symmetry might not need to obey Fermi-Dirac statistics, as there are no identical quarks present in such configurations.
  • One participant asserts that all up quarks in an uds baryon follow Fermi-Dirac statistics, although this is questioned in the context of flavor symmetry.
  • Another participant highlights that observable states of the uds baryon can be in symmetric or antisymmetric combinations, raising the question of why antisymmetry is still required despite the absence of identical particles.

Areas of Agreement / Disagreement

Participants express differing views on whether baryons with non-identical quark flavors must satisfy the antisymmetry requirement of their wavefunctions. The discussion remains unresolved, with multiple competing perspectives on the implications of flavor symmetry and the Pauli exclusion principle.

Contextual Notes

There are limitations regarding the assumptions made about flavor symmetry and the implications of the PEP in the context of baryons with different quark flavors. The discussion does not resolve the mathematical or conceptual nuances involved.

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).
 
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?
 
All the up quarks in an uds baryon follow the Fermi-Dirac statistics. For a single quark that is not a really interesting property.
 
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)
 

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