Square-integrable representations and the coadjoint action of solvable Lie groups

Fuente: arXiv
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Main Authors: Beltita, Ingrid, Beltita, Daniel
Format: Preprint
Published: 2021
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author Beltita, Ingrid
Beltita, Daniel
author_facet Beltita, Ingrid
Beltita, Daniel
contents We characterize the square-integrable representations of (connected, simply connected) solvable Lie groups in terms of the generalized orbits of the coadjoint action. We prove that the normal representations corresponding, via the Pukánszky correspondence, to open coadjoint orbits are type I, not necessarily square-integrable representations. We show that the quasi-equivalence classes of type I square-integrable representations are in bijection with the simply connected open coadjoint orbits, and the existence of an open coadjoint orbit guarantees the existence of a compact open subset of the space of primitive ideals of the group. When the nilradical has codimension 1, we prove that the isolated points of the primitive ideal space are always of type I. This is not always true for codimension greater than 2, as shown by specific examples of solvable Lie groups that have dense, but not locally closed, coadjoint orbits.
format Preprint
id arxiv_https___arxiv_org_abs_2111_01034
institution arXiv
publishDate 2021
record_format arxiv
spellingShingle Square-integrable representations and the coadjoint action of solvable Lie groups
Beltita, Ingrid
Beltita, Daniel
Representation Theory
Operator Algebras
Primary 22E27, Secondary 22D25, 22E25, 17B30
We characterize the square-integrable representations of (connected, simply connected) solvable Lie groups in terms of the generalized orbits of the coadjoint action. We prove that the normal representations corresponding, via the Pukánszky correspondence, to open coadjoint orbits are type I, not necessarily square-integrable representations. We show that the quasi-equivalence classes of type I square-integrable representations are in bijection with the simply connected open coadjoint orbits, and the existence of an open coadjoint orbit guarantees the existence of a compact open subset of the space of primitive ideals of the group. When the nilradical has codimension 1, we prove that the isolated points of the primitive ideal space are always of type I. This is not always true for codimension greater than 2, as shown by specific examples of solvable Lie groups that have dense, but not locally closed, coadjoint orbits.
title Square-integrable representations and the coadjoint action of solvable Lie groups
topic Representation Theory
Operator Algebras
Primary 22E27, Secondary 22D25, 22E25, 17B30
url https://arxiv.org/abs/2111.01034