Strong CP problem

The Strong CP problem is the question of why QCD or Quantum chromodynamics (our understanding of the Strong nuclear interaction and the secret of the binding of quarks into hadrons) does not violate CP-symmetry. CP-symmetry is a combination between charge conjugation symmetry with parity symmetry. In charge conjugation symmetry or C-symmetry, a particle is interchanged with its antiparticle. In parity symmetry or P-symmetry, a particle’s spatial coordinates are flipped or mirrored. It is according to Quantum chromodynamics that there should be a violation in the strong interaction. This violation has yet to be experimentally observed. This is a noted unsolved problem in particle physics.