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Laurent Clozel

Publications and source records attributed to Laurent Clozel.

14 recordsLinked to original sources
arXiv2026

Invariance Galoisienne des zéros centraux de fonctions L

Nous démontrons l'invariance Galoisienne de la propriété d'annulation en $1/2$ des fonctions L standard ou de Rankin-Selberg pour certaines représentations automorphes cuspidales algébriques régulières autoduales ou autoduales conjuguées de groupes linéaires sur un corps de nombres arbitraire. La démonstration repose sur l'utilisation de la cohomologie pondérée de Goresky-Harder-MacPherson et sur la construction de certaines représentations automorphes discrètes pour les groupes classiques comme résidus de séries d'Eisenstein. L'abandon de l'hypothèse ``$F$ totalement réel'' introduit de nouvelles difficultés concernant certains opérateurs d'entrelacement. Celles-ci sont résolues grâce à l'appendice, rédigé par J.-L. Waldspurger et l'un d'entre nous, démontrant l'holomorphie et la non-annulation de certains opérateurs d'entrelacement normalisés. Nous démontrons également l'invariance Galoisienne des facteurs epsilon correspondants, impliquant l'invariance Galoisienne de la parité de l'ordre d'annulation en $1/2$ de ces fonctions $L$. -- We prove the invariance under the Galois group of the vanishing at $1/2$ of standard and Rankin-Selberg L-functions for certain self-dual or conjugate self-dual algebraic cuspidal automorphic representations for general linear groups over an arbitrary number field. The proof uses Goresky-Harder-MacPherson weighted cohomology and the construction of certain discrete automorphic representations for classical groups as residues of Eisenstein series. New difficulties appear concerning certain intertwining operators. These are solved in the appendix by J.-L. Waldspurger and O. Taïbi proving the holomorphy and non-vanishing of these operators. We also prove the Galois invariance of epsilon factors, implying Galois invariance of the parity of the order at $1/2$ of L-functions.

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arXiv2024

Non-abelian base change for symmetric power liftings of holomorphic modular forms

Let $f$ be a non-CM Hecke eigenform of weight $k \geq 2$. We give a new proof of some cases of Langlands functoriality for the automorphic representation $π$ associated to $f$. More precisely, we prove the existence of the base change lifting, with respect to any totally real extension $F / \mathbb{Q}$, of any symmetric power lifting of $π$.

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arXiv2023

On the central value of Rankin $L$-functions for self-dual algebraic representations of linear groups over totally real fields

Deligne has formulated extremely influential conjectures about certain special values of the $L$-functions of (Grothendieck) motives over a number field $F$. Given the conjectural dictionary between motives and 'algebraic' automorphic representations of $\textrm{GL}(N, {\mathbb A}_F)$, where ${\mathbb A}_F$ denotes the adèles of $F$, they translate into conjectures concerning the $L$-functions of these automorphic representations. These complex representations, when they are 'regular', can be conjugated by the automorphisms of the complex field ${\mathbb C}$. It then follows, as a weak consequence of Deligne's conjectures, that the vanishing at critical points (integers of half-integers) of the automorphic $L$-functions should be invariant by automorphisms of ${\mathbb C}$. If $F$ is totally imaginary, this has been proven by Moeglin, for standard or Rankin $L$-functions. Here we extend the result to Rankin $L$-fuctions for totally real fields $F$, under a parity and a regularity assumption. The proof relies on Eisenstein cohomology and the Zucker conjecture (a theorem of Looijenga and Saper-Stern.)

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arXiv2023

Ordinary deformations are unobstructed in the cyclotomic limit

The deformation theory of ordinary representations of the absolute Galois groups of totally real number fields (over a finite field $k$) has been studied for a long time, starting with the work of Hida, Mazur and Tilouine, and continued by Wiles and others. Hida has studied the behaviour of these deformations when one considers the $p$-cyclotomic tower of extensions of the field. In the limit, one obtains a deformation ring $R_\infty$ classifying the ordinary deformations of the (Galois group of) the $p$-cyclotomic extension. We show that if $R_\infty$ is Noetherian and certain adjoint $μ$-invariants vanish (as is often expected), then $R_\infty$ is free over the ring of Witt vectors of $k$.

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arXiv2023

New applications of the Mellin transform to automorphic L-fuctions

Let L(s) = L(s, π) be the standard L-function of a cuspidal representation πof GL(m,A) where A denotes the adèles of the field of rationals. We consider the integral, on the real line Re(s)= 1/2, of the squared absolute value of L(s)/s. In an earlier paper, partly with P. Sarnak (arxiv:2203.12475) we obtained a universal lower bound on this integral, independently of m. In this paper, for m fixed, we first obtain a universal lower bound for the integral on an interval [-A logC, A log C] where C is the analytic conductor of π; this bound is of order c(log C)^{-1/2} ; A, c are absolute positive constants for m fixed. There is also an absolute lower bound on a shifted interval [X-T, X+T] where T is of the order of log X. In the second part of the paper, using the Mellin transform as in the previous paper, we estimate, for an irreducible, non trivial Galois representation ρof Gal(E/F), E and F being number fields, the smallest norm of a prime ideal P of F at which ρis unramified and ρ(Frob) is non-trivial, Frob being a Frobenius at P.

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arXiv2022

A universal lower bound for certain quadratic integrals of automorphic L-functions

We obtain uniform lower bounds, true for all automorphic L-functions L(s) associated to cuspidal representations of GL(m,A) where A denotes the adeles of the rationals Q, of the integral on the vertical line (Re(s)=1/2) of the absolute value squared of L(s)/s; and also of L(s)/(s-s_0) when s_0 is a zero of the L-function on the critical line. Several variants are also obtained in small degrees m, for the vertical integrals at different abscissas in the critical strip. For the estimates required to prove convergence, we are led to generalise a result of Friedlander-Iwaniec (Can. J. Math. 57,2005). We obtain new results on the abscissa of convergence of the L-series. Finally, a problem is posed about the behaviour of the quadratic integral when s_0 tends to infinity, in particular for the Riemann zeta function.

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arXiv2020

On the Eisenstein functoriality in cohomology for maximal parabolic subgroups

In his paper, 'On torsion in the cohomology of locally symmetric varieties', Peter Scholze has introduced a new, purely topological method to construct the cohomology classes on arithmetic quotients of symmetric spaces of rational reductive groups originating from the cohomology of the similar quotients of Levi subgroups of maximal parabolic subgroups. We extend this construction beyond the cases he considers, and, in the complex case, to the cohomology of local systems.

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arXiv2014

Sur le spectre et la topologie des variétés hyperboliques de congruence : les cas complexe et quaternionien

Building on results of Arthur and Mok, we extend to (finite volume) complex and quaternionic hyperbolic manifolds the results of arXiv:1004.1085. For the spherical spectrum our results are optimal. Finally, as an application we prove a Lefschetz property for the restriction map between arithmetic quotients of complex balls. This generalizes a recent theorem of Arvind Nair and gives an optimal version of it.

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arXiv2012

Comparaisons des exposants à l'intérieur d'un paquet d'Arthur archimédien

Generalizing the proof -- by Hecht and Schmid -- of Osborne's conjecture we prove an Archimedean (and weaker) version of a theorem of Colette Moeglin. The result we obtain is a precise Archimedean version of the general principle -- stated by the second author -- according to which {\it a local Arthur packet contains the corresponding local $L$-packet and representations which are more tempered.}

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arXiv2010

Quelques conséquences des travaux d'Arthur pour le spectre et la topologie des variétés hyperboliques

En nous basant sur les résultats d'Arthur annoncés dans \cite[§30]{Arthur} nous démontrons les conjectures énoncées dans \cite{IMRN,BC,SMF} dans le cas des groupes orthogonaux à l'exclusion des groupes de type ${}^6 - D_4$. En ce qui concerne ces derniers, nous annonçons la démonstration -- encore en préparation - que leur réseaux de congruences ont toujours un $H^1$ trivial. Les démonstrations d'Arthur devraient para\^ıtre prochainement.

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arXiv2008

Principe d'Heisenberg et fonctions positives

Starting from a problem in number theory, the article investigates the properties of the couples of Fourier transforms on the real line, f and g, real and even, f >= 0 out of an interval (-a, a) and f(0) < 0, g >= 0 out of an interval (-b, b) and g(0) < 0 . How small the product ab can be ? There is a strictly positive lower bound, the exact value is not known. The same problem is considered in several dimensions (where it is related to number theory, as the article points out).

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arXiv2007

Corps de nombres peu ramifies et formes automorphes autoduales

Let S be a finite set of primes, p in S, and Q_S a maximal algebraic extension of Q unramified outside S and infinity. Assume that |S|>=2. We show that the natural maps Gal(Q_p^bar/Q_p) --> Gal(Q_S/Q) are injective. Much of the paper is devoted to the problem of constructing selfdual automorphic cuspidal representations of GL(2n,A_Q) with prescribed properties at all places, that we study via the twisted trace formula of J. Arthur. The techniques we develop shed also some lights on the orthogonal/symplectic alternative for selfdual representations of GL(2n).

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arXiv1999

Equivalence numérique et équivalence cohomologique pour les variétés abéliennes sur les corps finis

In characteristic zero, it was proven a long time ago by D. Lieberman that cohomological and numerical equivalence coincide for cycles on abelian varieties. In this paper we show this to be true also in a somewhat technical sense for abelian varieties defined over a finite field. The technicality is that the result is valid for l-adic cohomology for primes l of non-zero density.

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