Clebsch-Gordan coefficient

== English == === Etymology === Named after the German mathematicians Alfred Clebsch and Paul Gordan, who encountered an equivalent problem in invariant theory. === Noun === Clebsch-Gordan coefficient (plural Clebsch-Gordan coefficients) (physics) Any of a class of numbers that arise in angular momentum coupling in quantum mechanics. They appear as the expansion coefficients of total angular momentum eigenstates in an uncoupled tensor product basis.