- #1
Rudipoo
- 32
- 0
Hi,
I was wondering whether the decay of the Pi-0 meson in QED to an electron positron pair can occur as follows:
Pi-0 -> virtual photon -> e+e-
or does it have to go via
Pi-0 -> two virtual photons -> e+e- (the Feynman diagram has a 'square' of virtual electrons/photons)?
I have a feeling it is forbidden via the first route but I'm unsure why, unless angular momentum has to be conserved within the diagram as well as for the beginning and end states?
Many thanks.
I was wondering whether the decay of the Pi-0 meson in QED to an electron positron pair can occur as follows:
Pi-0 -> virtual photon -> e+e-
or does it have to go via
Pi-0 -> two virtual photons -> e+e- (the Feynman diagram has a 'square' of virtual electrons/photons)?
I have a feeling it is forbidden via the first route but I'm unsure why, unless angular momentum has to be conserved within the diagram as well as for the beginning and end states?
Many thanks.