Solution
= Solution
Isotropic means invariant under every proper rotation. The general ranks $0,1,2,3$ are respectively a <scalar> $a$, zero, $b\delta_{ij}$, and $c\varepsilon_{ijk}$ (for full orthogonal invariance the last must also vanish).
= Solution
Isotropic means invariant under every proper rotation. The general ranks $0,1,2,3$ are respectively a <scalar> $a$, zero, $b\delta_{ij}$, and $c\varepsilon_{ijk}$ (for full orthogonal invariance the last must also vanish).