Spin and parity of pion decay

[Josh1079]

Hi, I'm recently reading Krane's nuclear physics textbook, and in the meson physics chapter there is a section about the spin and parity of pions. He demonstrated a way to find out the parity of the pion by investigating a pion decay(as in the attached images). I think I understand what he's doing, but I found it quite difficult to apply to other cases, such as π° → 2e+ 2e- , π- + d → 2n + π°. So can anyone demonstrate this method in these two cases?

Thanks!














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