Irreducibility of (anti)self-dual reps

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SUMMARY

The discussion focuses on the irreducibility of self-dual and antiself-dual representations within the second rank antisymmetric representation of the group SO(4). It is established that the projection of the space \(\Lambda^{2}V\) into these subspaces commutes with the action of SO(4). To demonstrate that these subspaces are irreducible, one must show that there are no proper submodules, which can be achieved by taking a basis vector and proving that its orbit encompasses the entire module.

PREREQUISITES
  • Understanding of group theory, specifically the properties of SO(4).
  • Familiarity with representation theory and the concept of irreducibility.
  • Knowledge of antisymmetric representations and their decomposition.
  • Basic linear algebra concepts, particularly vector spaces and submodules.
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  • Study the properties of SO(4) and its representations in detail.
  • Learn about the decomposition of antisymmetric representations in representation theory.
  • Explore the concept of orbits in the context of group actions on vector spaces.
  • Investigate examples of irreducible representations in other groups for comparative understanding.
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This discussion is beneficial for mathematicians, physicists, and researchers in representation theory, particularly those focusing on group representations and their applications in theoretical physics.

gentsagree
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Imagine we are talking about the group SO(4). The second rank antisymmetric representation is reducible into self-dual and antiself-dual representations. I think a good way to visualise this is by noticing that the projection of \Lambda^{2}V into self and antiself dual subspaces commutes with the action of SO(4).

However, how can I show that those subspaces are themselves irreducible?

Thanks!
 
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It would be easier to argue if you supply a more detailed framework. In general a representation is irreducible if there are no proper submodules. So you could take a basis vector and show that its orbit is the whole module.
 

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