\[\epsilon_{jk\ell}=\begin{cases}+1,&\text{if }j,k,\ell\text{ is even %
permutation of }1,2,3,\\
-1,&\text{if }j,k,\ell\text{ is odd permutation of }1,2,3,\\
\phantom{-}0,&\text{otherwise}.\end{cases}\]