SearcharxivSearch

arXiv subjects

Avner Segal

Publications and source records attributed to Avner Segal.

10 recordsLinked to original sources

Poles, Residues and Siegel-Weil Identities of Degenerate Eisenstein Series on Split Exceptional Groups of Type $E_n$

This manuscript has two goals: 1. To write an explicit description of the degenerate residual spectrum of the split, simple, simply-connected, exceptional groups of type $E_n$ (for $n=6,7,8$). 2. To set a practical guide for similar calculations and, in particular, to describe various methods of ``computational representation theory'' relevant to the study of residues of automorphic Eisenstein series. In Part I we supply background information and notations from the theory of automorphic representations as well as concrete information on the exceptional groups of type $E_n$ and their representation theory over non-Archimedean local fields. In Part II we make a systematic study of the residual spectrum of these groups where each chapter is devoted to a certain aspect of theory, it begins with methodical section and continues with sections devoted to the results for each of these groups. We describe completely the residual (square-integrable and non-square integrable) spectrum of the groups of type $E_6$ and $E_7$ and an almost complete description in the case of the group of type $E_8$. We also study and list Siegel-Weil like identities between residual representations of these groups and list the Arthur parameters for their square-integrable residual representations.

math.RT

Singularities of Intertwining Operators and Decompositions of Principal Series Representations

In this paper, we show that, under certain assumptions, a parabolic induction $Ind_B^Gλ$ from the Borel subgroup $B$ of a (real or $p$-adic) reductive group $G$ decomposes into a direct sum of the form: \[ Ind_B^Gλ= \left(Ind_P^G St_M\otimes χ_0\right) \oplus \left(Ind_P^G \mathbf{1}_M\otimes χ_0\right), \] where $P$ is a parabolic subgroup of $G$ with Levi subgroup $M$ of semi-simple rank $1$, $\mathbf{1}_M$ is the trivial representation of $M$, $St_M$ is the Steinberg representation of $M$ and $χ_0$ is a certain character of $M$. We construct examples of this phenomenon for all simply-connected simple groups of rank at least $2$.

math.RT

The Degenerate Residual Spectrum of Quasi-Split Forms of $Spin_8$ Associated to the Heisenberg Parabolic Subgroup

In \cite{MR3284482} and \cite{MR3658191}, the twisted standard $\mathcal{L}$-function $\mathcal{L}(s,π,χ,st)$ of a cuspidal representation $ π$ of the exceptional group of type $G_2$ was shown to be represented by a family of new-way Rankin-Selberg integrals. These integrals connect the analytic behaviour of $\mathcal{L}(s,π,χ,st)$ with that of a family of degenerate Eisenstein series $\mathcal{E}_E(χ, f_s, s, g)$ on quasi-split forms $H_E$ of $Spin_8$, induced from Heisenberg parabolic subgroups. The analytic behaviour of the series $\mathcal{E}_E(χ, f_s, s, g)$ in the right half-plane $Re(s)>0$ was studied in \cite{SegalEisen}. In this paper we study the residual representations associated with $\mathcal{E}_E(χ, f_s, s, g)$.

math.RT

The Degenerate Eisenstein Series Attached to the Heisenberg Parabolic Subgroups of Quasi-Split Forms of $Spin_8$

In previews works, joint with N. Gurevitch, a family of Rankin-Selberg integrals were shown to represent the twisted standard $\mathcal{L}$-function $\mathcal{L}\left(s,π,χ,\mathfrak{st}\right)$ of a cuspidal representation $ π$ of the exceptional group of type $G_2$. This integral representation binds the analytic behavior of this $\mathcal{L}$-functions with that of a degenerate Eisenstein series defined over the family of quasi-split forms of $Spin_8$ associated to an induction from a character on the Heisenberg parabolic subgroup. This paper is divided into two parts. In part 1 we study the poles of this degenerate Eisenstein series in the right half plane $\mathfrak{Re}(s)>0$. In part 2 we use the results of part 1 to give a criterion for $π$ to be a {\bf CAP} representation with respect to the Borel subgroup in terms of poles of $\mathcal{L}\left(s,π,χ,\mathfrak{st}\right)$. We also settle a conjecture of J. Hundley and D. Ginzburg and prove a few results relating the analytic behavior of $\mathcal{L}\left(s,π,χ,\mathfrak{st}\right)$ and the set of Fourier coefficients supported by $π$.

math.NT

Poles of the Standard $\mathcal{L}$-function of $G_2$ and the Rallis-Schiffmann Lift

We characterize the cuspidal representations of $G_2$ whose standard $\mathcal{L}$-function admits a pole at $s=2$ as the image of Rallis-Schiffmann lift for the commuting pair $\left(\widetilde{SL_2}, G_2\right)$ in $\widetilde{Sp_{14}}$. The image consists of non-tempered representations. The main tool is the recent construction, by the second author, of a family of Rankin-Selberg integrals representing the standard $\mathcal{L}$-function.

math.RT

A Family of New-way Integrals for the Standard $\mathcal{L}$-function of Cuspidal Representations of the Exceptional Group of Type $G_2$

Let $\mathcal{L}^{S}\left(s,π,χ,\operatorname{\mathfrak{st}}\right)$ be a standard twisted partial $\mathcal{L}$-function of degree $7$ of the cuspidal automorphic representation $π$ of the exceptional group of type $G_2$. In this paper we construct a family of Rankin-Selberg integrals representing this $\mathcal{L}$-function. As an application, we prove that the representations attaining certain prescribed poles are exactly the representations attained by $θ$-lift from a group of finite type.

math.RT