Eisenstein series on arithmetic quotients of rank 2 Kac--Moody groups over finite fields

Fuente: arXiv
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Autores principales: Ali, Abid, Carbone, Lisa, Garrett, Paul
Formato: Preprint
Publicado: 2021
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author Ali, Abid
Carbone, Lisa
Garrett, Paul
author_facet Ali, Abid
Carbone, Lisa
Garrett, Paul
contents Let $G$ be an affine or hyperbolic rank 2 Kac--Moody group over a finite field $\mathbb F_q$. Let $X=X_{q+1}$ be the Tits building of $G$, the $(q+1)$--homogeneous tree, and let $Γ$ be a non-uniform lattice in $G$. When $Γ$ is a standard parabolic subgroup for the negative $BN$--pair, we define Eisenstein series on $Γ\backslash X$ and prove its convergence in a half space using Iwasawa decomposition of the Haar measure on $G$. A crucial tool is a description of the vertices of $X$ in terms of Iwasawa cells. We also prove meromorphic continuation of the Eisenstein series. This requires us to construct an integral operator on the Tits building $X$ and a truncation operator for the Eisenstein series. We also develop the functional analytic framework necessary for proving meromorphic continuation in our setting, by refining and extending Bernstein's Continuation Principle.
format Preprint
id arxiv_https___arxiv_org_abs_2108_02919
institution arXiv
publishDate 2021
record_format arxiv
spellingShingle Eisenstein series on arithmetic quotients of rank 2 Kac--Moody groups over finite fields
Ali, Abid
Carbone, Lisa
Garrett, Paul
Number Theory
Group Theory
Let $G$ be an affine or hyperbolic rank 2 Kac--Moody group over a finite field $\mathbb F_q$. Let $X=X_{q+1}$ be the Tits building of $G$, the $(q+1)$--homogeneous tree, and let $Γ$ be a non-uniform lattice in $G$. When $Γ$ is a standard parabolic subgroup for the negative $BN$--pair, we define Eisenstein series on $Γ\backslash X$ and prove its convergence in a half space using Iwasawa decomposition of the Haar measure on $G$. A crucial tool is a description of the vertices of $X$ in terms of Iwasawa cells. We also prove meromorphic continuation of the Eisenstein series. This requires us to construct an integral operator on the Tits building $X$ and a truncation operator for the Eisenstein series. We also develop the functional analytic framework necessary for proving meromorphic continuation in our setting, by refining and extending Bernstein's Continuation Principle.
title Eisenstein series on arithmetic quotients of rank 2 Kac--Moody groups over finite fields
topic Number Theory
Group Theory
url https://arxiv.org/abs/2108.02919