Particle Interactions, proton + antiproton

[leonmate]

Quite a simple query really,

The question wants me to draw a Feynman diagram for a number of particle interactions, some are not possible, some are.

This interaction:

proton + antiproton ----> 3 gamma

This would require each quark (uud) to annihilate with its anti matter counter part. This is fine, but this produces gluons not photons. I know these gluons can decay into particles, and they could then maybe annihilate into photons.

Is this interaction, as it's stated, possible to be demonstrated using Feynman diagrams?

 

[Orodruin]

This is fine, but this produces gluons not photons.

Not necessarily, quarks have electromagnetic charge and therefore also couple to photons.