Val Logsdon Fitch

Val Logsdon Fitch was an American experimental physicist who shared the 1980 Nobel Prize in Physics for discovering charge-parity violation in neutral-kaon decay.

James Cronin: American experimental physicist who shared the 1980 Nobel Prize in Physics for discovering charge-parity violation in neutral-kaon decay. Fitch and Cronin led the experiment that revealed the same unexpected kaon decay.
Neutral kaon: A short-lived meson that exists as a mixture of neutral K-zero and anti-K-zero states. Fitch’s experiment tracked neutral kaons as they changed identity and decayed.
Manhattan Project: The United States-led wartime program that developed the first atomic weapons. Fitch served in its electromagnetic-separation work while stationed at Oak Ridge.
Baryon asymmetry: The observed excess of matter over antimatter in the universe. CP violation became one ingredient in theories explaining why the universe contains more matter.
Charge conjugation: A transformation that replaces every particle in a physical system with its antiparticle. CP violation means charge conjugation paired with parity does not preserve all kaon decays.
Maurice Goldhaber: Physicist known for experimental work on nuclear and particle physics, including neutrino helicity. Goldhaber directed Brookhaven’s physics department when Fitch and Cronin began their kaon experiment.
CP violation: A failure of physical processes to remain unchanged under the combined operations of charge conjugation and parity inversion. The rare decay observed by Fitch and Cronin provided the first evidence of this symmetry breaking.
Oak Ridge National Laboratory: A United States research laboratory established during the Manhattan Project in Tennessee. Fitch’s wartime assignment there introduced him to experimental nuclear physics.
Sakharov conditions: Three requirements for generating a matter–antimatter imbalance from an initially symmetric universe. One condition requires processes that violate charge-parity symmetry, a phenomenon Fitch helped establish.
Parity (physics): A spatial transformation that reverses all coordinates through the origin. The kaon discovery concerned parity combined with charge conjugation, not parity alone.

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Toshihide MaskawaRelated: Fitch co-led the experiment that revealed the symmetry breaking addressed by Maskawa's theory.