The Fitch and Cronin experiment is put forward as one of the very few examples of CP violation in weak interactions and as a possible explanation for matter anti-matter asymmetry. The decay channels are K → 3 pions K → pi-plus + electron + antineutrino K → pi-minus + positron + neutrino Of these the neutral kaons prefer to decay into the positron channel. Griffith's says that if CP weren't violated these last two decays would have an equal probability of happening. How can a preference for antimatter can be used to explain a dominance of matter? Also in the second decay an antineutrino is produced is this somehow less important in this respect than the positron?