I am studying the annihilation processes and read that electron-positron annihilation releases 2 photons. I know that releasing 1 photon is not possible because it violates the conservation of $E$. But it can decay into more than two photons, such as three for positronium decay. I am a little confused with the terms.
Does positronium decay mean the same as electron-positron annihilation?
How can we draw Feynman diagrams for such a case where 2 particles release three identical particles and find the corresponding amplitude and energy? Can anyone explain?
