
Journal of Lie Theory 22 (2012), No. 2, 491503 Copyright Heldermann Verlag 2012 On the Dual Topology of a Class of Cartan Motion Groups Majdi Ben Halima Department of Mathematics, Faculty of Sciences, University of Sfax, Route de Soukra  B.P.1171, 3000 Sfax, Tunisia majdi.benhalima@yahoo.fr Aymen Rahali Department of Mathematics, Faculty of Sciences, University of Sfax, Route de Soukra  B.P.1171, 3000 Sfax, Tunisia [Abstractpdf] \def\g{{\frak g}} Let $(G,K)$ be a compact Riemannian symmetric pair, and let $G_{0}$ be the associated Cartan motion group. Under some assumptions on the pair $(G,K)$, we give a precise description of the set $(\widehat{G_{0}})_{\rm gen}$ of all equivalence classes of generic irreducible unitary representations of $G_{0}$. We also determine the topology of the space $(\g_{0}^{\ddagger}/G_{0})_{gen}$ of generic admissible coadjoint orbits of $G_{0}$ and we show that the bijection between $(\widehat{G_{0}})_{\rm gen}$ and $(\g_{0}^{\ddagger}/G_{0})_{\rm gen}$ is a homeomorphism. Furthermore, in the case where the pair $(G,K)$ has rank one, we prove that the unitary dual $\widehat{G_{0}}$ is homeomorphic to the space $\g_{0}^{\ddagger}/G_{0}$ of all admissible coadjoint orbits of $G_{0}$. Keywords: Symmetric space, motion group, induced representation, coadjoint orbit. MSC: 53C35, 22D05, 22D30, 53D05 [ Fulltextpdf (346 KB)] for subscribers only. 