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Let H be any reductive p-adic group. We introduce a notion of cuspidality for enhanced Langlands parameters for H, which conjecturally puts supercuspidal H-representations in bijection with such L-parameters. We also define a cuspidal…

Representation Theory · Mathematics 2025-05-09 Anne-Marie Aubert , Ahmed Moussaoui , Maarten Solleveld

Let $U$ be an algebraic subgroup of the group of $n\times n$ upper-triangular matrices with units on the diagonal over a finite field of large enough characteristic, and $\mathfrak{n}$ be the Lie algebra of $U$. The main tool in…

Representation Theory · Mathematics 2026-04-03 Mikhail Ignatev , Leonid Titov

Let $G$ be a reductive group in the Harish-Chandra class e.g. a connected semisimple Lie group with finite center, or the group of real points of a connected reductive algebraic group defined over $\R$. Let $\sigma$ be an involution of the…

Representation Theory · Mathematics 2007-05-23 Patrick Delorme

We give a complete description of the bounded (i.e. norm continuous) unitary representations of the Fr\'echet-Lie algebra of all smooth sections, as well as of the LF-Lie algebra of compactly supported smooth sections, of a smooth Lie…

Representation Theory · Mathematics 2021-08-10 Bas Janssens , Karl-Hermann Neeb

For a Hermitian Lie group $G$, we study the family of representations induced from a character of the maximal parabolic subgroup $P=MAN$ whose unipotent radical $N$ is a Heisenberg group. Realizing these representations in the non-compact…

Representation Theory · Mathematics 2023-04-17 Jan Frahm , Clemens Weiske , Genkai Zhang

Let G be a possibly disconnected reductive real Lie group. In this paper, I parametrize the set of irreductible tempered characters of G. I then describe these characters using certain ``Kirillov's formulas,'' based on the descent method…

Representation Theory · Mathematics 2026-01-29 Jean-Yves Ducloux

For a simple real Lie group $G$ with Heisenberg parabolic subgroup $P$, we study the corresponding degenerate principal series representations. For a certain induction parameter the kernel of the conformally invariant system of second order…

Representation Theory · Mathematics 2024-04-25 Jan Frahm

Let $G$ be a complex reductive algebraic group. In arXiv:2108.03453, we have defined a finite set of irreducible admissible representations of $G$ called `unipotent representations', generalizing the special unipotent representations of…

Representation Theory · Mathematics 2023-09-27 Lucas Mason-Brown , Dmytro Matvieievskyi , Shilin Yu

The main result describes the Brauer-Nesbitt reduction of unipotent representations of a finite group of Lie type, expressing it as an explicit linear combination of the restriction of Weyl modules from the algebraic group to the group of…

Representation Theory · Mathematics 2026-04-01 Roman Bezrukavnikov , Michael Finkelberg , David Kazhdan , Calder Morton-Ferguson

The irreducible unitary representations of the Banach Lie group $U_0(\H)$ (which is the norm-closure of the inductive limit $\cup_k U(k)$) of unitary operators on a separable Hilbert space $\H$, which were found by Kirillov and Ol'shanskii,…

High Energy Physics - Theory · Physics 2007-05-23 N. P. Landsman

We attempt to reconstruct the irreducible unitary representations of the Banach Lie group $U_0(\H)$ of all unitary operators $U$ on a separable Hilbert space $\H$ for which $U-{\mathbb I}$ is compact, originally found by Kirillov and…

Mathematical Physics · Physics 2015-06-26 Nicolaas P. Landsman

If $G$ is a Lie group, $H\subset G$ is a closed subgroup, and $\tau$ is a unitary representation of $H$, then the authors give a sufficient condition on $\xi\in i\mathfrak{g}^*$ to be in the wave front set of $\operatorname{Ind}_H^G\tau$.…

Representation Theory · Mathematics 2016-04-06 Benjamin Harris , Hongyu He , Gestur Olafsson

Let G be a reductive connected p-adic group. With help of the Fourier inversion formula used in [Une formule de Plancherel pour l'algebre de Hecke d'un groupe reductif p-adique - V. Heiermann, Comm. Math. Helv. 76, 388-415, 2001] we give a…

Representation Theory · Mathematics 2007-05-23 Volker Heiermann

Hiraga, Ichino and Ikeda have conjectured an explicit expression for the Plancherel density of the group of points of a reductive group defined over a local field $F$, in terms of local Langlands parameters. In these lectures we shall…

Representation Theory · Mathematics 2018-07-30 Eric Opdam

Let G be a connected reductive real Lie group, and H a compact connected subgroup. Harish-Chandra associates to a regular coadjoint admissible orbit M of G some unitary representations of G. Using the character formula for these…

Representation Theory · Mathematics 2011-10-06 Michel Duflo , Michèle Vergne

We introduce graded Hecke algebras H based on a (possibly disconnected) complex reductive group G and a cuspidal local system L on a unipotent orbit of a Levi subgroup M of G. These generalize the graded Hecke algebras defined and…

Representation Theory · Mathematics 2019-01-28 Anne-Marie Aubert , Ahmed Moussaoui , Maarten Solleveld

We examine from an algebraic point of view some families of unitary group representations that arise in mathematical physics and are associated to contraction families of Lie groups. The contraction families of groups relate different real…

Representation Theory · Mathematics 2017-09-12 Joseph Bernstein , Nigel Higson , Eyal Subag

We demonstrate the main idea of constructing irreducible unitary representations of Lie groups by using Fedosov deformation quantization in the concrete case of the group Aff(R) of affine transformations of the real straight line. By an…

Quantum Algebra · Mathematics 2007-05-23 Do Ngoc Diep , Nguyen Viet Hai

As is known, the irreducible projective representations (Reps) of anti-unitary groups contain three different situations, namely, the real, the complex and quaternion types with torsion number 1,2,4 respectively. This subtlety increases the…

Mathematical Physics · Physics 2021-06-11 Zhen-Yuan Yang , Jian Yang , Chen Fang , Zheng-Xin Liu

A unitary representation of a, possibly infinite dimensional, Lie group $G$ is called semibounded if the corresponding operators $i\dd\pi(x)$ from the derived representation are uniformly bounded from above on some non-empty open subset of…

Representation Theory · Mathematics 2011-05-23 Karl-Hermann Neeb