I've previously asked a question on here about if it was possible to change the barion number by radioactive decay, for example positron emission, and the answer was of course no, as the baryon number rmains consistent. I've also talked about this problem with some friends, and one of them came up with a process to turn baryonic matter into purely energy or leptons. Basically, their idea was, that, at first, a proton and an antiproton should annihilate each other, which should only leave energy, and the resulting photons should then, by the mechanism of pair production create an electron and a positron. Of course, to an amateur like me, this makes sense. But, as Baryon number is supposed to be consistent, this shouldn't work? Can someone explain why or why not this works? It would be greatly apreciated.
If you start with a proton and an anti-proton, the initial baryon number is zero, so there is no problem with ending up in a state with zero baryon number such as an electron and positron. According to wikipedia, typically mesons are an intermediate product in such a reaction, and you may also produce photons and neutrinos.