Conformally invariant differential operators on Heisenberg groups and minimal representations

Fuente: arXiv
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Autore principale: Frahm, Jan
Natura: Preprint
Pubblicazione: 2020
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author Frahm, Jan
author_facet Frahm, Jan
contents 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 differential operators constructed by Barchini, Kable and Zierau is a subrepresentation which turns out to be the minimal representation. To study this subrepresentation, we take the Heisenberg group Fourier transform in the non-compact picture and show that it yields a new realization of the minimal representation on a space of $L^2$-functions. The Lie algebra action is given by differential operators of order $\leq3$ and we find explicit formulas for the functions constituting the lowest $K$-type. These $L^2$-models were previously known for the groups $\operatorname{SO}(n,n)$, $E_{6(6)}$, $E_{7(7)}$ and $E_{8(8)}$ by Kazhdan and Savin, for the group $G_{2(2)}$ by Gelfand, and for the group $\widetilde{\operatorname{SL}}(3,\mathbb{R})$ by Torasso, using different methods. Our new approach provides a uniform and systematic treatment of these cases and also constructs new $L^2$-models for $E_{6(2)}$, $E_{7(-5)}$ and $E_{8(-24)}$ for which the minimal representation is a continuation of the quaternionic discrete series, and for the groups $\widetilde{\operatorname{SO}}(p,q)$ with either $p\geq q=3$ or $p,q\geq4$ and $p+q$ even. As a byproduct of our construction, we find an explicit formula for the group action of a non-trivial Weyl group element that, together with the simple action of a parabolic subgroup, generates $G$.
format Preprint
id arxiv_https___arxiv_org_abs_2012_05952
institution arXiv
publishDate 2020
record_format arxiv
spellingShingle Conformally invariant differential operators on Heisenberg groups and minimal representations
Frahm, Jan
Representation Theory
Primary 22E45, Secondary 22E46, 35R03, 43A30
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 differential operators constructed by Barchini, Kable and Zierau is a subrepresentation which turns out to be the minimal representation. To study this subrepresentation, we take the Heisenberg group Fourier transform in the non-compact picture and show that it yields a new realization of the minimal representation on a space of $L^2$-functions. The Lie algebra action is given by differential operators of order $\leq3$ and we find explicit formulas for the functions constituting the lowest $K$-type. These $L^2$-models were previously known for the groups $\operatorname{SO}(n,n)$, $E_{6(6)}$, $E_{7(7)}$ and $E_{8(8)}$ by Kazhdan and Savin, for the group $G_{2(2)}$ by Gelfand, and for the group $\widetilde{\operatorname{SL}}(3,\mathbb{R})$ by Torasso, using different methods. Our new approach provides a uniform and systematic treatment of these cases and also constructs new $L^2$-models for $E_{6(2)}$, $E_{7(-5)}$ and $E_{8(-24)}$ for which the minimal representation is a continuation of the quaternionic discrete series, and for the groups $\widetilde{\operatorname{SO}}(p,q)$ with either $p\geq q=3$ or $p,q\geq4$ and $p+q$ even. As a byproduct of our construction, we find an explicit formula for the group action of a non-trivial Weyl group element that, together with the simple action of a parabolic subgroup, generates $G$.
title Conformally invariant differential operators on Heisenberg groups and minimal representations
topic Representation Theory
Primary 22E45, Secondary 22E46, 35R03, 43A30
url https://arxiv.org/abs/2012.05952