arXiv subjects

David Ginzburg

Publications and source records attributed to David Ginzburg.

29 records · Page 2Linked to original sources

arXiv2015

Descent and Theta Functions for Metaplectic Groups

There are few constructions of square-integrable automorphic functions on metaplectic groups. Such functions may be obtained by the residues of certain Eisenstein series on covers of groups, "theta functions," but the Fourier coefficients of these residues are not well-understood, even for low degree covers of $GL_2$. Patterson and Chinta-Friedberg-Hoffstein proposed conjectured relations for the Fourier coefficients of the $GL_2$ quartic and sextic theta functions (resp.), each obtained from a conjectured equality of non-Eulerian Dirichlet series. In this article we propose a new framework for constructing specific $L^2$ metaplectic functions and for understanding these conjectures: descent integrals. We study descent integrals which begin with theta functions on covers of larger rank classical groups and use them to construct certain $L^2$ metaplectic functions on covers related to $GL_2$. We then establish information about the Fourier coefficients of these metaplectic automorphic functions, properties which are consistent with the conjectures of Patterson and Chinta-Friedberg-Hoffstein. In particular, we prove that Fourier coefficients of the descent functions are arithmetic for infinitely many primes $p$. We also show that they generate a representation with non-zero projection to the space of theta. We conjecture that the descents may be used to realize the quartic and sextic theta functions. Moreover, this framework suggests that each of the conjectures of Patterson and Chinta-Friedberg-Hoffstein is the first in a series of relations between certain Fourier coefficients of two automorphic forms on different covering groups.

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arXiv2015

Criteria for the Existence of Cuspidal Theta Representations

Theta representations appear globally as the residues of Eisenstein series on covers of groups; their unramified local constituents may be characterized as subquotients of certain principal series. A cuspidal theta representation is one which is equal to the local twisted theta representation at almost all places. Cuspidal theta representations are known to exist but only for covers of $GL_j$, $j\leq 3$. In this paper we establish necessary conditions for the existence of cuspidal theta representations on the $r$-fold metaplectic cover of the general linear group of arbitrary rank.

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arXiv2015

On the Genericity of Eisenstein Series and Their Residues for Covers of $GL_m$

Let $τ_1^{(r)}$, $τ_2^{(r)}$ be two genuine cuspidal automorphic representations on $r$-fold covers of the adelic points of the general linear groups $GL_{n_1}$, $GL_{n_2}$, resp., and let $E(g,s)$ be the associated Eisenstein series on an $r$-fold cover of $GL_{n_1+n_2}$. Then the value or residue at any point $s=s_0$ of $E(g,s)$ is an automorphic form, and generates an automorphic representation. In this note we show that if $n_1\neq n_2$ these automorphic representations (when not identically zero) are generic, while if $n_1=n_2:=n$ they are generic except for residues at $s=\frac{n\pm1}{2n}$.

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arXiv2015

Classification of some Global Integrals related to groups of type $A_n$

In this paper we start a classification of certain global integrals. First, we use the language of unipotent orbits to write down a family of global integrals. We then classify all those integrals which satisfy the dimension equation we set. After doing so, we check which of these integrals are global unipotent integrals. We do all this for groups of type $A_n$, and using all this we derive a certain interesting conjecture about the length of these integrals.

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arXiv2015

On Certain Global Constructions of Automorphic Forms Related to Small Representations of $F_4$

In this paper we consider some global constructions of liftings of automorphic representations attached to some commuting pairs in the exceptional group $F_4$. We consider two families of integrals. The first uses the minimal representation on the double cover of $F_4$, and in the second we consider examples of integrals of descent type associated with unipotent orbits of $F_4$.

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arXiv2014

Metaplectic Theta Functions and Global Integrals

We convolve a theta function on an $n$-fold cover of $GL_3$ with an automorphic form on an $n'$-fold cover of $GL_2$ for suitable $n,n'$. To do so, we induce the theta function to the $n$-fold cover of $GL_4$ and use a Shalika integral. We show that in particular when $n=n'=3$ this construction gives a new Eulerian integral for an automorphic form on the 3-fold cover of $GL_2$ (the first such integral was given by Bump and Hoffstein), and when $n=4$, $n'=2$, it gives a Dirichlet series with analytic continuation and functional equation that involves both the Fourier coefficients of an automorphic form of half-integral weight and quartic Gauss sums. The analysis of these cases is based on the uniqueness of the Whittaker model for the local exceptional representation. The constructions studied here may be put in the context of a larger family of global integrals which are constructed using automorphic representations on covering groups. We sketch this wider context and some related conjectures.

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arXiv2012

A doubling integral for G2

We introduce a new integral representation for the standard L-function of an irreducible cuspidal automorphic representation of the exceptional group G2, and also for the twist of this L-function by an arbitrary character. Because our construction unfolds to a matrix coefficient rather than a Whittaker function, it applies to non-generic representations as well as generic ones.

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arXiv2011

Constructions of global integrals in the exceptional groups

Motivated by known examples of global integrals which represent automorphic L-functions, this paper initiates the study of a certain two-dimensional array of global integrals attached to any reductive algebraic group, indexed by maximal parabolic subgroups in one direction and by unipotent conjugacy classes in the other. Fourier coefficients attached to unipotent classes, Gelfand-Kirillov dimension of automorphic representations, and an identity which, empirically, appears to constrain the unfolding process are presented in detail with examples selected from the exceptional groups. Two new Eulerian integrals are included among these examples.

math.RT↗

arXiv2005

On Spin L-functions for GSO_10

In this paper we construct a Rankin-Selberg integral which represents the Spin_10 x St L-function attached to the group GSO_10 x PGL_2. We use this integral representation to give some equivalent conditions for a generic cuspidal representation on GSO_10 to be a functorial lift from the group G_2 x PGL_2.

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arXiv2005

A New Tower of Rankin-Selberg Integrals

This document describes the authors' current research project: the evaluation of a tower of Rankin-Selberg integrals on the group E_6. We recall the notion of a tower, and two known towers, making observations about how the integrals within a tower may be related to one another via formal manipulations, and offering a heuristic for how the L-functions should be related to one another when the integrals are related in this way. A detailed description of the E_6 tower is then given.

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arXiv1999

On explicit lifts of cusp forms from GL_m to classical groups

In this paper, we begin the study of poles of partial L-functions L^S(sigma tensor tau,s), where sigma tensor tau is an irreducible, automorphic, cuspidal, generic (i.e. with nontrivial Whittaker coefficient) representation of G_A x GL_m(A). G is a split classical group and A is the adele ring of a number field F. We also consider tilde{Sp}_{2n}(A) x GL_m(A), where tilde denotes the metaplectic cover.

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