Question: Why does matter and antimatter kaon particles produce predominantly left spinning electrons

Ondrej Kovanda answered on 10 Mar 2020:

Kaon decays are driven by one of the fundamental forces, which we call the ‘weak interaction’. It follows from a bunch of quantum-field-theoretical calculations and symmetry considerations, that the structure of the weak interaction incorporates so called ‘vector’ and ‘axial vector currents’. The latter are responsible for altering a probability of processes with particles of certain spin orientations (called helicity). Therefore, one orientation may be favoured over the other. Answering if (and how much) the left spinning electrons are favoured in the kaon decays would require to carry out this rather lengthy calculation 🙂