Is SU(3) always contains SU(2) groups?

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    Groups Su(2) Su(3)
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Discussion Overview

The discussion revolves around the relationship between the special unitary groups SU(3) and SU(2), specifically whether SU(3) always contains SU(2) as a subgroup. Participants also explore the implications of this relationship in the context of group compatibility, particularly in relation to SU(3) and SU(3) x SU(2) x U(1).

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant questions if a non-trivial SU(3) group always contains an SU(2) subgroup.
  • Another participant asserts that there are many SU(2) subgroups of SU(3), drawing a parallel to the relationship between O(2) and O(3).
  • A further inquiry is made about the compatibility of SU(3) with SU(3) x SU(2) x U(1), suggesting that since SU(3) contains SU(2) subgroups and SU(2) contains U(1), there may be a compatibility.
  • A participant clarifies that the group product G1 x G2 represents independent groups and questions the meaning of "compatible" in this context.

Areas of Agreement / Disagreement

Participants express differing views on the nature of subgroup inclusion and compatibility, indicating that the discussion remains unresolved with multiple competing perspectives.

Contextual Notes

There are limitations regarding the definitions of compatibility and subgroup inclusion, as well as the mathematical rigor in the discussion of group structures.

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Hi,

I trying to understand. If there is non-trivial SU(3) group, is it always possible to find SU(2) as part of SU(3)?
And same question about SU(2) and U(1).
 
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Sure, there are many ##SU(2)## subgroups of ##SU(3)## just like there are many ##O(2)## subgroups of ##O(3)##.
 
Thanks.

And another question about same.
SU(3) seems as have less number of parameters than SU(3)xSU(2)xU(1).
If there is SU(3) group, is is possible to say it is compatible with SU(3)xSU(2)xU(1) because SU(3) always contains SU(2) subgroups, and SU(2) always contains U(1)?
 
The group, ##G_1\times G_2## is the tensor product of two independent groups. ##G_1## is contained in ##G_1\times G_2## by the projection ##\pi : (g1,g2)\rightarrow g1##. The subgroup inclusion discussed in my previous reply is a subgroup of a different sort. (Mathematics is not my strongest subject) It would help to know what you mean by "compatible?"
 
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