Note that the two-body intermediate state is assumed to be antisymmetric but
not normalized, that is, the state which involves the quantum numbers
\( j_a \) and \( j_b \). Assume that the intermediate
two-body state is antisymmetric. With this coupling order, we can
rewrite ( in a schematic way) the general three-particle Slater determinant as
$$
\Phi(a,b,c) = {\cal A} | ([j_a\rightarrow j_b]J_{ab}\rightarrow j_c) J\rangle,
$$
with an implicit sum over \( J_{ab} \). The antisymmetrization operator \( {\cal A} \) is used here to indicate that we need to antisymmetrize the state.
Challenge: Use the definition of the \( 6j \) symbol and find an explicit
expression for the above three-body state using the coupling order \( | ([j_a\rightarrow j_b]J_{ab}\rightarrow j_c) J\rangle \).