Octets for Baryons: What is the Other Octet?

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SUMMARY

The discussion centers on the identification of the second octet in baryon classification within the context of quark theory. The participant references the decomposition of the product of three fundamental representations, specifically 3 ⊗ 3 ⊗ 3 = 10 ⊕ 8 ⊕ 8 ⊕ 1, and seeks clarification on the nature of the other octet and the singlet state. It is established that quarks adhere to Fermi-Dirac statistics, and the formation of baryons requires consideration of flavor, color, space, and spin components. The Λ(1890) is proposed as a potential SU(3) singlet baryon, necessitating orbital angular momentum for its formation.

PREREQUISITES
  • Understanding of SU(3) symmetry in particle physics
  • Familiarity with quark model and baryon classification
  • Knowledge of Fermi-Dirac statistics and wavefunction symmetries
  • Basic concepts of angular momentum in quantum mechanics
NEXT STEPS
  • Research the properties of the Λ(1890) baryon and its implications in particle physics
  • Study the role of orbital angular momentum in baryon formation
  • Explore the classification of baryons using SU(3) symmetry
  • Learn about the construction of wavefunctions for systems of identical fermions
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Particle physicists, students of quantum mechanics, and researchers interested in baryon classification and quark dynamics will benefit from this discussion.

jono90one
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Hi,
I am just learning some materials and struggling to find what the other octet is. I know the following:
3 \otimes 3 \otimes 3 = 10 \oplus 8 \oplus 8 \oplus 1

Now I understand the 10 and one of the 8's. But I am a little unsure of what the other octet and singlet is in terms of quarks. Is the other octet just an excited state of the other octet (higher spin)??

http://proj.ncku.edu.tw/research/articles/e/20080523/images/080408014859tzxABW.gif
(This is the octet I already know)

Thanks.
 
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Quarks must obey Fermi-Driac statistics. Their wavefunction is a product of four parts: flavor, color, space and spin. All hadrons are colorless, meaning the color part is totally antisymmetric. In a ground state one assumes L = 0, meaning the space part is totally symmetric. This leaves flavor and spin, which together must be totally symmetric.

An SU(3) singlet is totally antisymmetric, meaning it wants to be combined with a totally antisymmetric spin part.

But three spin-halfs can only be combined in two ways: either as S = 3/2 (totally symmetric) or S = 1/2 (mixed). There is no totally antisymmetric way to combine three spin-halfs.

So the only remaining way to make a baryon which is an SU(3) singlet is to include orbital angular momentum. It's believed that the Λ(1890) is such a particle.
 

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