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Construction of canonical coordinates for exponential Lie groups

2009, Trans. Amer. Math. Soc

Abstract

Given an exponential Lie group G, we show that the constructions of [5] go through for a less restrictive choice of Jordan-Hölder basis. Thus we obtain a stratification of g * into G-invariant algebraic subsets, and for each such subset Ω, an explicit cross-section Σ ⊂ Ω for coadjoint orbits in Ω, so that each pair (Ω, Σ) behaves predictably under the associated restriction maps on g * . The cross-section mapping σ : Ω → Σ is explicitly shown to be real analytic. The associated Vergne polarizations are not necessarily real even in the nilpotent case, and vary rationally with ∈ Ω. For each Ω, algebras E 0 (Ω) and E 1 (Ω) of polarized and quantizable functions respectively, are defined in a natural and intrinsic way.