Fun fact; the standard model actually allows for spontaneous particle-antiparticle pair generation, so long as the pair mutually annihilate within some hbar defined time limit and conservation laws aren’t broken at a macro scale. This is the mechanism behind hawking radiation too; some of the energy given off by black holes is caused by spontaneous pair generation that happens such that one of the pair is created beyond the event horizon and the other member is created before the event horizon, causing one to be trapped and the other to be jettisoned into space.

I know that doesn’t really relate to your comment about containing antimatter but I counter with the following: I’m profoundly autistic and the standard model has been a special interest of mine before. I couldn’t resist the chance to infodump a bit