Dear bloftin,
Thanks for your fast answer, that's really helpful.
I'm still confused at one point, just like "chicken first or eggs first" question. In your answer you said:
> ... a spinor is represented by the SU(2) group ...
, however, in my opinion, the symmetry, i.e. the group is more fundamental, the spinor is only one representation of SU(2). I mean a group can have different representations, these representations should even have different dimensions. For example, in particle physics, a requirement is free particles would be under the constraint named Lorentz transformation invariant, i.e. the SO(3,1) group. Here we have two representations, tensor and spinor, which all can be used to describe real particles in order to fulfill this "rotation invariant" requirement.
So, we can say "SU(2) group can be represented by spinor", but the reverse is incorrect. Am I right? |
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