Wigner small-d matrix
= Wigner small-d matrix
{c}
{title2=$d^j_{m'm}(\theta)=\langle j,m'|e^{-iJ_y\theta}|j,m\rangle$}
The rotation matrix about the $y$ axis in a spin-$j$ angular-momentum representation. For $j=1$, $d^1_{-1,+1}=(1-\cos\theta)/2$; its square gives the polar dependence of a transition between those <spin angular momentum>[spin projections].