Angular momentum singlet state
= Angular momentum singlet state
{wiki=Singlet_state}
= Rotation singlet
{synonym}
Two equal spins $j$ have the unique total-spin-zero state
$$
|0,0\rangle=\frac1{\sqrt{2j+1}}
\sum_{m=-j}^j(-1)^{j-m}|j,m\rangle|j,-m\rangle.
$$
It is invariant under joint rotations.