What do 1, 2, 3 represent in $\operatorname{U}(1)+\operatorname{SU}(2)+\operatorname{SU}(3)$?
If they are dimensions, how they can be added? or plus has another meaning?
What do 1, 2, 3 represent in $\operatorname{U}(1)+\operatorname{SU}(2)+\operatorname{SU}(3)$?
3
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lie-groups
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0$U(n)$ is the unitary group of $n\times n$ matrices. And $SU(n)$ is the special unitary group of $n\times n$ matrices. Should the + be a $\times$? – 2011-02-10
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2Are you talking about Lie groups or Lie algebras? – 2011-02-10
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0i guess Lie groups as i am not sure whether it is in gauge theory, how dimension 1x1 times 2x2 times 3x3? or U is matrix 1x2 times SU 2x3 times SU 3x3? – 2011-02-11
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0I don't quite understand what you're asking. – 2011-02-11