Big break for charge symmetry

The experiments detecting the aspects of charge symmetry breaking were reported. The masses of protons and neutrons were calculated using quantum chromodynamics (QCD) and electromagnetism. The difference between the up and down quarks in neutrons and protons resulted in the production of neutral-pions. In regard with the breaking of charge symmetry, the interactions of pions with protons and neutrons and the relation of spin angular momentum of fundamental particles is discussed.