Can protons and antiprotons annihilate into photons?

Answer 1

Yes. You get two gamma photons. Lighter particles like electrons and anti electrons also give you photons. You just get much lower energy photons, like light or radio frequency. If you got other particles, it wouldn't be annihilation. That word describes the total conversion of mass.

Answer 2

The electron and positron at low energy are small enough to annihilate and produce only two photons. But a proton-antiproton collision would need to produce some other heavy particles. The products would depend on the energy of the collision. Photons can still result.

Answer 3

Yes they can as any other particle-antiparticle pair. Once a proton and an antiproton come close enough to each other they will immediately annihilate into two photons. Since the proton is a heavy particle the photons will have a lot of energy (they will be gamma rays).

Answer 4

I believe they just annihilate each other, the same way as an electron and a positron.