I'm currently studying the two-body decay where a particle (Be) with spin-1 decays into a pion (spin-0) and spin-1 particle $X$. The system is prepared so that the Be is polarized with a spin projection of +1 in the $x$-axis, this led me to conclude that there are two possible decays.
One where the Be-X state has $L=0$ with m(X)=1 and one where $L=2$ with m(X)=-1.
My question is when calculating angular distributions, what specific things should be taken into account?
Is the only thing influencing the distribution the orbital angular momentum, in which case I just calculate spherical harmonics, or is there another factor?