state why p + p_bar --> 1 photon
The Attempt at a Solution
I have checked all quantum numbers and they are okay. I wondering altough if p_bar has intrinsic parity -1 (p has parity +1)??
According to the soloution, it is forbidden because of energy and momentum conservation. I have not been giving a single word about the production conditions and so forth. HOW can this (E and p) be violated if I choose whatever annihilation condition so that p and E is not violated??!!