Seminars Sorted by Series

I will discuss several results on abstract homomorphisms between the groups of rational points of algebraic groups. The main focus will be on a conjecture of Borel and Tits formulated in their landmark 1973 paper.

Our results settle this conjecture...

The representation theory of reductive groups on categories is the geometric counterpart to the representation theory of reductive groups over finite fields. I will describe, following joint work with Sam Gunningham, a geometric counterpart for...

Consider a pair $(X,\widehat{L})$ of a regular and projective algebraic variety over $\mathbb{Q}$ and a semipositive adelically metrized line bundle $\widehat{L}$ over $X$. Assume that all of Zhang's successive minima of the pair $(X,\widehat{L})$...

The classical conjectures of Ramanujan-Petersson and Sato-Tate on the Fourier coefficients of modular forms, or more generally on the Satake parameters of automorphic representations, are highly sensitive to questions of functoriality. For example...

We prove the modularity of some two-dimensional residually reducible p-adic Galois representations over Q under certain hypothesis on the residual representation at p. To do this, we generalize Emerton's local-global compatibility result and devise...

A basic but difficult question in the analytic theory of automorphic forms is: given a reductive group G and a representation r of its L-group, how many automorphic representations of bounded analytic conductor are there? In this talk I will present...

In this talk, we construct the so-called Fourier-Jacobi cycles on unitary Shimura varieties. The height pairing of these cycles can be regarded as the arithmetic analogue of classical Fourier-Jacobi periods for the pair of unitary groups of equal...

Braverman and Kazhdan have conjectured the existence of summation formulae that are essentially equivalent to the analytic continuation and functional equation of Langlands L-functions in great generality. Motivated by their conjectures and related...

Deformation spaces of representations of Galois groups of p-adic fields with p-adic Hodge theoretic conditions play a central role in many arithmetic questions, such as the weight part of Serre's conjecture and modularity lifting theorems, yet they...

I will try to explain what the Fourier expansion of a "modular form" on an exceptional group looks like, from the point of view of the archimedean place. In more detail, Gross-Wallach and Gan-Gross-Savin have singled out what a modular form on an...

This talk will be an exposition of a circle of ideas that concerns the cohomology of arithmetic groups and the special values of certain automorphic L-functions. I will explain some recent results about the critical values of (1) Rankin-Selberg L...

The analytic theory of Poincaré series and Maass cusp forms and their L-functions for $SL(3,Z)$ has, so far, been limited to the spherical Maass forms, i.e. elements of a spectral basis for $L^2(SL(3,Z)\PSL(3,R)/SO(3,R))$. I will describe the Maass...

S-operators were originally introduced by V. Lafforgue as certain operators acting on the cohomology of moduli of Shtukas. I will discuss their analogues and generalizations in the Shimura variety setting. They induce Hecke equivariant maps between...

The Faltings height is a useful invariant for addressing questions in arithmetic geometry. In his celebrated proof of the Mordell and Shafarevich conjectures, Faltings shows the Faltings height satisfies a certain Northcott property, which allows...

The Langlands-Rapoport conjecture gives a description of the mod $p$ points of suitable integral models of Shimura varieties. Such results are of use, for example, in computing the local factor of the (semi-simple) Hasse-Weil zeta function of the...

At the November workshop, I described a new algorithm to cover compact, congruence locally symmetric spaces by balls. I’ll discuss how to compute the nerve of such a covering and Hecke actions on its cohomology. Joint work with Aurel Page.At the...

I will describe recent work with Ngaiming Mok and Jacob Tsimerman giving analogues of "Ax-Schanuel" for Shimura varieties. I will sketch the role of "o-minimal structures" in the proof, in particular point counting and powerful algebraicity results...

Let $E$ be a CM elliptic curve over a totally real number field $F$ and $p$ an odd ordinary prime. If the ${p^{\infty}\mbox{-}\mathrm{Selmer}}$ group of $E$ over $F$ has ${\mathbb{Z}_{p}\mbox{-}\mathrm{corank}}$ one, we show that the analytic rank...

We explain the magic of the entire function $\Psi_p \in \mathbb{Z}[x] \cap \mathbb{Q}_p\{x\}$ defined by the functional equation \[x = \sum_{j=0}^{\infty} p^{-j}\Psi_p (p^{j} x)^{p^{j}}\] which satisfies $\Psi_p (\mathbb{Q}_p) \subset \mathbb{Z}_p$...

We start by showing that for any 1-parameter family of genus $g>2$ curves, the number of rational points is bounded by $g$, degree of the field, and the Mordell-Weil rank. Apart from the classical Faltings-Vojta-Bombieri method, the new input is a...

Given an elliptic curve $E$ over $\mathbb{Q}$, a celebrated conjecture of Goldfeld asserts that a positive proportion of its quadratic twists should have analytic rank 0 (resp. 1). We show this conjecture holds whenever $E$ has a rational 3-isogeny...

We introduce a new $p$-adic Maass-Shimura operator acting on a space of "generalized $p$-adic modular forms" (extending Katz's notion of $p$-adic modular forms) defined on the $p$-adic (preperfectoid) universal cover of Shimura curves. Using this...

In the late 1950’s, Burgess developed a novel method for bounding short sums of a multiplicative Dirichlet character. This resulted in a subconvexity bound for Dirichlet $L$-functions on the critical line. In recent work, we have adapted the Burgess...

In his influential paper "Modular curves and the Eisenstein ideal", Mazur studied congruences modulo p between cusp forms and the Eisenstein series of weight 2 and prime level N. In particular, he defined the Eisenstein ideal in the relevant Hecke...

The seminal work of Deligne and Lusztig on the representations of finite reductive groups has influenced an industry studying parallel constructions in the same theme. In this talk, we will discuss recent progress on studying analogues of Deligne-...

Proving the equidistribution of roots of quadratic congruences, with strong estimates on the Weyl sums, is one of the most spectacular applications of the spectral theory of automorphic forms to arithmetic. See for example Duke, Friedlander and...

Hilbert’s 12th problem is to provide explicit analytic formulae for elements generating the maximal abelian extension of a given number field. In this talk I will describe an approach to Hilbert’s 12th that involves proving exact p-adic formulae for...

Honda-Tate theory says that every abelian variety mod p is isogenous to the reduction of a CM abelian variety.We will discuss the analogous statement for isogeny classes on Shimura varieties, and explain what is conjectured and what is known.

Affine Deligne-Lusztig varieties (ADLV) naturally arise in the study of Shimura varieties and Rapoport-Zink spaces; their irreducible components give rise to interesting algebraic cycles on the special fiber of Shimura varieties. We prove a...

Saito--Tunnell theorem is a local version of Waldspurger's formula, relating the existence of E^\times invariant linear forms on representation of GL_2 to local root numbers. I present a generalization of this which relates the existence of GL_n(E)...

I will begin with a gentle introduction to hyperrings and hyperfields (originally introduced by Krasner for number-theoretic reasons), and then discuss a far-reaching generalization, Oliver Lorscheid’s theory of ordered blueprints. Two key examples...

It is known that the modular curve has good reduction at $p$ if the level structure is prime to $p$. If the level structure is of $\Gamma_0(p)$-type, then the modular curve has semi-stable reduction. For general Shimura varieties, one may ask for...

We study the function field analogue of a classical problem in analytic number theory on the sums of the generalized divisor function in short intervals, in the limit as the degrees of the polynomials go to infinity. As a corollary, we calculate...

I will present a computation of the integral p-adic etale cohomology of the Drinfeld half-space. Via integral p-adic Hodge Theory of Bhatt-Morrow-Scholze this reduces to a computation of the integral de Rham cohomology and this can be done...

The study of eigenvarieties began with Coleman and Mazur, who constructed the first eigencurve, a rigid analytic space parametrizing $p$-adic modular Hecke eigenforms. Since then various authors have constructed eigenvarieties for automorphic forms...

Over one-dimensional bases, Gabber and Beilinson proved theorems on the commutation of the nearby cycle functor and the vanishing cycle functor with duality. In this talk, I will explain a way to unify the two theorems, confirming a prediction of...

In 1973, Serre observed that the Hecke eigenvalues of Eisenstein series can be p-adically interpolated. In other words, Eisenstein series can be viewed as specializations of a p-adic family parametrized by the weight. The notion of p-adic variations...

This talk is concerned with the radius of convergence of p-adic families of modular forms --- q-series over a p-adic disc whose specialization to certain integer points is the q-expansion of a classical Hecke eigenform of level p. Numerical...

I will explain a new proof of the geometric stabilization theorem for Hitchin fibers, a key ingredient in Ngô's proof of the fundamental lemma. Our approach relies on ideas of Denef-Loeser and Batyrev on p-adic integration and Langlands duality for...

In 1987, Barry Mazur and John Tate formulated refined conjectures of the "Birch and Swinnerton-Dyer type", and one of these conjectures was essentially proved in the prime conductor case by Ehud de Shalit in 1995. One of the main objects in de...

Wiles's proof of the modularity of semistable elliptic curves over the rationals uses the Langlands-Tunnell theorem as a starting point, implying that the mod 3 Galois representation attached to the elliptic curve arises from a modular form of...

The point of this talk is to give three examples of derived structures influencing representations that have connections with number theory. These structures arise from the differential graded algebra of group cochains valued in the endomorphism...

Extending on the work of Kudla-Millson and Yuan-Zhang-Zhang, together with Yott we are constructing special divisors for a specific GSpin Shimura variety. We further construct a generating series that has as coefficients the cohomology classes...

The thesis of Akshay Venkatesh obtains a Beyond Endoscopy'' proof of stable functorial transfer from tori to ${\rm SL}(2)$, by means of the Kuznetsov formula. In this talk, I will show that there is a local statement that underlies this work; namely...

Number fields with the same Dedekind zeta function are said to be arithmetically equivalent. Such number fields necessarily have the same degree, discriminant, signature, Galois closure, and isomorphic unit groups, but may have different regulators...

The theory of complex multiplication describes finite abelian extensions of imaginary quadratic number fields using singular moduli, which are special values of modular functions at CM points. I will describe joint work with Henri Darmon in the...

The Sato-Tate group of an abelian variety A of dimension g defined over a number field is a compact real Lie subgroup of the unitary simplectic group of degree 2g that conjecturally governs the limiting distribution of the normalized Frobenius...

On an elliptic curve $y^2=x^3+ax+b$, the points with coordinates $(x,y)$ in a given number field form a finitely generated abelian group. One natural question is how the rank of this group changes when changing the number field. For the simplest...