>>11911157The quark has a left part and a right part. As it walks across the spacetime, it oscillates back and forth from right part to left part and from left part to right part. From analyzing the Wu experiment's demonstration of parity violation, it can be deduced that only the left part of down quarks decay and the weak interaction involves only the left part of quarks and leptons (or the right part of antiquarks and antileptons). The right part of the particle simply does not feel the weak interaction. If the down quark did not have mass it would not oscillate, and its right part would be quite stable by itself. Yet, because the down quark is massive, it oscillates and decays.[19]
