One small caveat - neutrino/antineutrino "annihilations" have never been detected, and probably almost never happen in nature. There is a whole branch of experimental physics with 10s of large scale experiments looking for this process (neutrinoless double beta decay experiments). And there are scores of theoretical physicists developing theories in which neutrinos don't have antiparticles (Majorana neutrinos). People doubt neutrinos are majorana particles only because that would be odd - since all the other fermions are not majorana in the known universe.