My question is: Does angular momentum conservation considerations alone forbid a spin-1/2 particle from decaying into two spin-1/2 particles?
According to this Phys.SE post, the answer seems to argue that you cannot add two spin-1/2 particles and get a spin-1/2 particle. Yes, I understand that the tensor product of two spin-1/2 particles can be re-organised as a direct sum of a spin-1 space and spin-0 space. However, I disagree that this forbids the decay, because orbital angular momentum could change such that spin+orbital angular momentum ends up being conserved. Hence I believe that under angular momentum conservation considerations alone, it is still possible to for the decay to happen. Is this reasoning correct?