Physicists soon came up with a way to make the laws look better again. While it was found that only
lefthanded neutrinos exist in nature, it was also found that only righthanded antineutrinos exist.
This meant that while a parity exchange on its own does not always produce the right equations, applying a
parity exchange and swapping all particles for their antiparticles should work. Physicists call the
process of switching particle for antiparticle charge conjugation. They discovered that their equations were
symmetric under a combined parity exchange (P) and charge conjugation (C)  they were CP invariant.
All this means is that if you take the equation of motion for a neutrino and switch +x for x the
resulting equation does not correctly describe a neutrino. However, if you then switch neutrino for
antineutrino the equation works again.
Everything seemed to work very well, until 1964....
