Neutron decay is not aan electromagnetic phenomenaphenomenon at all. It is governed by the weak nuclear force. This is well supported by fact that the lifetime of the neutron fits neatly into weak universality, by the energy distribution of neutron decay products, and by the fact that anti-neutrino initiated "inverse beta decay" can be shown to be proportional to the power of near-by nuclernearby nuclear reactors or to beam intensity in accelerator experiments.
Secondly the neutron is not it's own antiparticle. The anti-neutron is a distinct particle.
