Canonical structure constants for simple Lie algebras

Abstract

Let gbe a finite-dimensional simple Lie algebra over C. In the 1950s Chevalley showed that gadmits particular bases, now called “Chevalley bases”, for which the corresponding structure constants are integers. Such bases are not unique but, using Lusztig’s theory of canonical bases, one can single out a “canonical” Chevalley basis which is unique up to a global sign. In this paper, we give explicit formulae for the structure constants with respect to such a basis.