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In mathematics, the Dynkin index : of a representation with highest weight of a compact simple Lie algebra ''g'' that has a highest weight is defined by : evaluated in the representation . Here are the matrices representing the generators, and is : evaluated in the defining representation. By taking traces, we find that : where the Weyl vector : is equal to half of the sum of all the positive roots of ''g''. The expression is the value quadratic Casimir in the representation . The index is always a positive integer. In the particular case where is the highest root, meaning that is the adjoint representation, is equal to the dual Coxeter number. ==References== * Philippe Di Francesco, Pierre Mathieu, David Sénéchal, ''Conformal Field Theory'', 1997 Springer-Verlag New York, ISBN 0-387-94785-X 抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「Dynkin index」の詳細全文を読む スポンサード リンク
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