- #176
arivero
Gold Member
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- 173
CarlB said:I should exhibit a representation of SU(2) which does not satisfy the requirement that the geometrically defined squared magnitude is equivalent to the usual spinor squared magnitude (and therefore to the traces). So here it is:
[tex]\sigma_x = \left(\begin{array}{cc}0.0&0.2\\5.0&0.0\end{array}\right)[/tex]
[tex]\sigma_y = \left(\begin{array}{cc}0.0&-0.2i\\5.0i&0.0\end{array}\right)[/tex]
[tex]\sigma_z = \left(\begin{array}{cc}1.0&0.0\\0.0&-1.0\end{array}\right)[/tex]
It is more a sort of deformation of SU(2) than a representation of [the infinitesimal generators of] SU(2), isn't it? People expects selfadjointness to get unitary generators, thus unitary group, which is the thing that the U stands for, after all. Just terminology issue, but it can be a communication problem.