Unitary and Nonunitary Representations of the Heisenberg-Weyl Lie Algebra

Fuente: arXiv
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Main Authors: Douglas, Andrew, de Guise, Hubert, Repka, Joe
Format: Preprint
Published: 2026
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author Douglas, Andrew
de Guise, Hubert
Repka, Joe
author_facet Douglas, Andrew
de Guise, Hubert
Repka, Joe
contents We examine unitary and nonunitary representations of the Heisenberg-Weyl Lie algebra $\mathfrak{hw}_n$, with particular emphasis on tensor products of unitary representations and on indecomposable nonunitary representations. In the unitary setting, the irreducible representations with nontrivial central character are the Schrödinger representations, as classified by the Stone-von Neumann theorem. Although tensor products of these representations are considered in the literature, we give a detailed Lie-algebraic analysis and construct explicit unitary intertwining operators, including the case where the central characters sum to zero. In the nonunitary setting, we consider a natural realization of $\mathfrak{hw}_n$ as a subalgebra of the real symplectic Lie algebra $\mathfrak{sp}_{2n+2}(\mathbb R)$ and prove that every finite-dimensional complex irreducible representation of $\mathfrak{sp}_{2n+2}(\mathbb{R})$ remains indecomposable upon restriction to $\mathfrak{hw}_n$. This yields a large natural family of finite-dimensional, nonunitary indecomposable representations of $\mathfrak{hw}_n$.
format Preprint
id arxiv_https___arxiv_org_abs_2603_05782
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Unitary and Nonunitary Representations of the Heisenberg-Weyl Lie Algebra
Douglas, Andrew
de Guise, Hubert
Repka, Joe
Representation Theory
17B10, 17B20, 17B30, 22E25, 22E27
We examine unitary and nonunitary representations of the Heisenberg-Weyl Lie algebra $\mathfrak{hw}_n$, with particular emphasis on tensor products of unitary representations and on indecomposable nonunitary representations. In the unitary setting, the irreducible representations with nontrivial central character are the Schrödinger representations, as classified by the Stone-von Neumann theorem. Although tensor products of these representations are considered in the literature, we give a detailed Lie-algebraic analysis and construct explicit unitary intertwining operators, including the case where the central characters sum to zero. In the nonunitary setting, we consider a natural realization of $\mathfrak{hw}_n$ as a subalgebra of the real symplectic Lie algebra $\mathfrak{sp}_{2n+2}(\mathbb R)$ and prove that every finite-dimensional complex irreducible representation of $\mathfrak{sp}_{2n+2}(\mathbb{R})$ remains indecomposable upon restriction to $\mathfrak{hw}_n$. This yields a large natural family of finite-dimensional, nonunitary indecomposable representations of $\mathfrak{hw}_n$.
title Unitary and Nonunitary Representations of the Heisenberg-Weyl Lie Algebra
topic Representation Theory
17B10, 17B20, 17B30, 22E25, 22E27
url https://arxiv.org/abs/2603.05782