Questions tagged [langlands-conjectures]

Higher reciprocity laws

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0 answers
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Basic question on the Langlands conjectures for $GL_n$ over global field of positive characteristic

My field is far from the Langlands conjectures. I am just trying to understand some basic ideas. At the moment I am interested in a global field $K$ of positive characteristic and the group $G=GL_n$. ...
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4 votes
1 answer
126 views

On a theorem of Bernstein-Zelevinsky regarding supercuspidal resentations

Let $G$ be a $p$-adic reductive group and $\pi$ an irreducible non-supercuspidal representation. Then there exist a parbaolic subgroup $P=MN$ and a supercuspidal representation of $M$ such that $\pi$ ...
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8 votes
1 answer
295 views

Is the nonvanishing of Langlands L-functions at $s=1$ conjectured?

Suppose $G$ is a semisimple algebraic group over the rational numbers, $\pi$ is a cuspidal automorphic representation of $G$, and $r: \widehat{G}(\mathbf{C}) \rightarrow \mathrm{GL}_N(\mathbf{C})$ is ...
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15 votes
1 answer
957 views

How does the cohomology of the Lubin-Tate/Drinfeld tower fit into categorical p-adic local Langlands?

In conjecture 6.1.14 of this article, Emerton-Gee-Hellmann formulate the p-adic local Langlands conjecture, which posits the existence of a fully faithful functor from (the appropriate derived ...
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5 votes
0 answers
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Finite coefficients Langlands for function fields

Do we have a finite coefficients Langlands correspondence for function fields? By which I mean a bijection between Galois representations $$\pi_1(X)\to \mathrm{GL}_n\left(\overline{\mathbb{F}_p}\right)...
2 votes
0 answers
154 views

Why are they called reductive groups? [duplicate]

The reductive groups play a central role in the Langlands correspondence. Why are these groups called reductive? Does this name suggest something conceptual about these groups?
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1 vote
1 answer
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From Galois representations to automorphic forms for $\mathfrak{sl}_2$ (via Drinfeld's shtukas)

Drinfeld-Lafforgue have proven function fields Langlands conjectures in type A: see https://arxiv.org/pdf/math/0212417.pdf (Laumon's survey in English), https://arxiv.org/pdf/math/0212399.pdf (...
3 votes
0 answers
91 views

Understanding Shimura correspondence in context of Langlands functoriality

Recently, I started to read about automorphic forms and representations on covering groups, e.g. metaplectic groups. I set my first goal as understanding Shimura's correspondence in representation ...
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7 votes
1 answer
389 views

Non-existence of "higher" Artin map

So rank $1$ local Langlands is special in as that it is given by the Artin map $$\text{GL}_1(K)\to G_K^{ab},$$ whereas in the higher rank (to the best of my knowledge) there doesn't exist a map $$\...
18 votes
1 answer
2k views

What are "branes", and why do they form a category?

I've been trying to read Kapustin–Witten - Electric–Magnetic Duality And The Geometric Langlands Program recently, as someone whose mathematical interests are in the Langlands program. I have some ...
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4 votes
1 answer
246 views

modularity lifting theorems for non-compact unitary groups

I am reading David Geraghty's paper, 'Modularity lifting theorems for ordinary Galois representations'(https://link.springer.com/article/10.1007/s00208-018-1742-4) and I have a related question, which,...
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5 votes
1 answer
169 views

Motive associated to a cuspidal representation of $GSp_{4}$

In the paper by L.Clozel in this book (a French text), there is this conjecture (conjecture 4.5 p139) Conjecture: Given $\pi$ an algebraic cuspidal representation of $Gl(n)$ of weight $w$ and denote ...
9 votes
1 answer
218 views

History of points of view on Eisenstein series

What is the history of Eisenstein series? Did the mathematician Eisenstein actually encounter them? There are, as far as I know, two major perspectives on what Eisenstein series are. The first is in ...
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3 votes
1 answer
109 views

The meaning of $L_{\chi}^2(G(\mathbb Q) \backslash G(\mathbb A)^1)$

I'm reading James Arthur's notes on the trace formula and am confused on a point on pages 65 and 66. For $G$ a reductive group over $\mathbb Q$ we are going over the decomposition of the space $L^2(G(...
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13 votes
2 answers
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Relationship between the TQFTs in Kapustin-Witten and Ben-Zvi-Sakellaridis-Venkatesh

In upcoming work of Ben-Zvi-Sakellaridis-Venkatesh, (see for instance these notes or this lecture) some important aspects of the Langlands correspondence are stated in the language of topological ...
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6 votes
0 answers
460 views

Affine GIT quotients and the excursion algebra in Fargues–Scholze

Some background: Let us fix a non-archimedean local field $E$ with residue characteristic $p$, and let $G$ be some connected reductive group over $E$. In [FS, §VIII.1.1] the authors define a moduli ...
4 votes
0 answers
153 views

The link between Satake parameter and Godement-Jacquet L-function of an automorphic representation of $GL_{n}$

Origin of the question: I'm reading the following survey of K. Martin, more generally I'm looking for the "best way" to define L-function associated to an automorphic representation of a ...
5 votes
0 answers
379 views

Do we expect the Langlands correspondence to be a functor?

In the literature I've read, it is often said that to a Hecke eigenclass, one would like (and sometimes succeeds) to "associate" or show the existence of a Galois representation such that ...
2 votes
1 answer
107 views

Do Artin L functions have polynomial growth in in the critical strip?

Given an irreducible representation $\rho$ of the Galois group $G$ of a number field $K$ over $\mathbb{Q}$, we have the associated Artin $L$ function which we denote by $L(s, \rho)$. By Brauer ...
4 votes
0 answers
152 views

From $\mathrm{GL}_{1}/K$ to $\mathrm{GL}_{2}/\mathbb{Q}$, where $K$ is a cyclic cubic extension

(Migrated from MSE) Let $K$ be a cyclic cubic extension of $\mathbb{Q}$. For example, one can take simplest cubic fields. By automorphic induction (which is known for cyclic extension of prime degree ...
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2 votes
0 answers
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Converse of Gelbart-Jacquet lift for $\mathrm{GL}(3)$ Maass forms

(This question is migrated from MSE) Gelbart-Jacquet lift gives functoriality from $\mathrm{GL}(2)$ to $\mathrm{GL}(3)$ that corresponds to a symmetric square map $\mathrm{Sym}^{2}: \mathrm{GL}(2, \...
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2 votes
0 answers
85 views

Local A-packet is singleton for unramified place?

Let $\pi$ be a generic $A$-parameter, that is an isobaric automorphic representation of linear group. Decompose $\pi= \otimes \pi_v$ as a restricted tensor product. Then by the local Langlands ...
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Generic Arthur-parameter of symplectic group

For a irreducible cuspidal automorphic representation $\pi$ of $Sp(2n)$, we can attach its generic $A$-parameter, that is isobaric sum automorphic representation of $GL_{2n+1}$. I know it is of the ...
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4 votes
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125 views

Global Vogan A-packet is infinite set?

For an cuspidal automorphic representation of general linear group, we can attach its global Vogan A-packet. Though I thought that it is finite set, in some paper, it is written that there are ...
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2 votes
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Representation of locally profinite group

$\DeclareMathOperator\Hom{Hom}\DeclareMathOperator\GL{GL}$In Bushnell and Henniart's "The local Langlands conjecture for $\GL_2$", Chapter 1, 3.5, proof of the duality theorem it says For ...
8 votes
1 answer
224 views

A question about mod $p$ local Langlands for $\mathrm{GL}_{2}(\mathbb{Q}_{p})$

In the mod $p$ local Langlands correspondence for $\mathrm{GL}_{2}(\mathbb{Q}_{p})$, the irreducible supercuspidal representation $\left(\mathrm{ind}^{\mathrm{GL}_{2}(\mathbb{Q}_{p})}_{\mathrm{GL}_{2}(...
15 votes
0 answers
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A question on Fargues-Scholze

As far as I understand it, the main goal of the recent work of Fargues and Scholze on the geometrization conjecture is to show that the local Langlands conjecture of a local field is equivalent to the ...
19 votes
1 answer
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Cohomology of Shimura varieties and coherent sheaves on the stack of Langlands parameters

In Zhu's Coherent sheaves on the stack of Langlands parameters theorem 4.7.1 relates the cohomology of the moduli stack of shtukas to global sections of a certain sheaf on the stack of global ...
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1 vote
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Langlands program and complexity theory

Back when I was an undergraduate, I spent some time reading the about the modularity conjecture, but the details are fuzzy now. One of the motivations I imagined for the Langlands program was for ...
4 votes
1 answer
507 views

Categorical-geometric Langlands for tori

Fix a "nice" curve $X$ (smooth, projective, proper, geometrically connected, what-have-you) and an algebraic torus $G$, both over a field of characteristic $0$ (possibly algebraically closed?...
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3 votes
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Density of the Mellin transform inside the direct integral of induced representations

I'm trying to better understand the continuous spectrum of $G = \operatorname{GL}_2(\mathbb A_{\mathbb Q})$, which is the direct integral of induced representations $\mathbf H(s) = \operatorname{Ind}_{...
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3 votes
0 answers
138 views

$p$-adic Hodge theoretic properties of global Galois representations via $\ell$-Frobenii

Let $G_{\mathbb{Q},S} = \mathrm{Gal}(\mathbb{Q}_S/\mathbb Q)$ where $\mathbb Q_S$ is the largest algebraic extension of $\mathbb Q$ unramified outside a finite set of places $S$. Then the union over $\...
3 votes
0 answers
114 views

The mystery of the jumps of functions with the prescribed jumps: Eisenstein series and hidden symmetries(?)

Say that a function $f(t)$ “changes only by jumps” if $f(t) + \text{const} = C ∑_k j_k θ(t-t_k)$ for a certain constant $C$. Here $θ(t)$ is the Heaviside step function which has a jump 1 at $t=0$ (it ...
1 vote
1 answer
222 views

The norm of the principal series intertwining operator for $\operatorname{GL}_2$

Is there a known bound on the norm of the standard intertwining operator for the principal series of $G = \operatorname{GL}_2(\mathbb Q_p)$? Background: For a character $\chi = (\chi_1,\chi_2)$ of the ...
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3 votes
1 answer
89 views

Calculating the residue of Eisenstein series from the residue of the intertwining operator

I've been reading the article Forms of $\operatorname{GL}(2)$ from the analytic point of view by Gelbart and Jacquet in Corvallis and am confused on a particular claim (equation 5.17 on page 232). The ...
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4 votes
0 answers
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How to see the surjectivity of $L^2_{\text{cont}}$ onto the direct integral of Hilbert space representations?

I've been reading the article Forms of $\operatorname{GL}(2)$ from the analytic point of view by Gelbart and Jacquet in Corvallis and am confused on one point. Let $G = \operatorname{GL}_2$, and $V = ...
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9 votes
1 answer
186 views

Why are characters orthogonal to cusp forms?

Let $G = \operatorname{GL}_2$, and let $V = L^2(Z(\mathbb A)G(\mathbb Q) \backslash G(\mathbb A),\omega)$, for $\omega$ a character of the ideles $\mathbb A^{\ast}$, identified with a central ...
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6 votes
1 answer
636 views

Contemporary introduction to Godement-Jacquet "Zeta functions of simple algebras"

The question is in the title: The book Godement-Jacquet "Zeta functions of simple algebras" is from 1971. Has there ever been a textbook introduction to this material, or at least part of it?...
7 votes
1 answer
436 views

Dictionary of arithmetic symmetries and Langlands

To a number theorist automorphic forms appear to be adelic point-counting generating functions for arithmetic schemes. This is what the conjectured equality of their $L$ functions tells us. The fact ...
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11 votes
1 answer
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Eigenvarieties and functoriality

In Langlands' review of Hida's book "$p$-adic automorphic forms on Shimura varieties", he discusses a nexus of 4 areas of modern number theory: automorphic representations, motives, spaces ...
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10 votes
1 answer
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Modularity of higher genus curves

The modularity conjecture for elliptic curves over number fields is well known, and indeed, is a theorem for all elliptic curves over $\mathbb{Q}$, and at least potentially, over any CM field. What ...
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6 votes
2 answers
607 views

What is the theorem of the highest weight used for?

$\DeclareMathOperator\End{End}$Over the past few months, I have taught myself the classification of reductive groups, and continued to non-abelian (as well as a small venture to non-compact) Harmonic ...
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14 votes
0 answers
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Exposition of Drinfeld's proof of function field Langlands for GL(2)

I know, or think I know, the vague outline of the proof: the Galois-to-automorphic direction is "classical," i.e. follows from converse theorems due to Grothendieck et al., and for the ...
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12 votes
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How do we deduce the Jacquet-Langlands correspondence from Fargues' two towers?

In trying to understand the geometric proof of the local-Langlands and Jacquet-Langlands correspondence which uses Fargues's two tower theorem, I am having trouble finding a nice source on this, and I ...
25 votes
0 answers
544 views

Galois representations attached to Shimura varieties - after a decade

In an answer to the question Tools for the Langlands Program?, Emerton, in his usual illuminating manner, remarks on the reciprocity aspect of Langlands Program: "...As to constructing Galois ...
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5 votes
1 answer
442 views

What is a map for the representation theory of reductive groups?

I have finished learning about linear algebraic groups (minus their representation theory) and the associated algebraic structures (root data, root systems, etc.), and will next attempt to summarize ...
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8 votes
0 answers
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On a remark of Langlands

I'm been wondering about this for a while and hope someone can enlighten me. In this interview of Robert Langlands's from 2010, on pg 21 (Question 8) he states "At one point, when fairly young, I ...
6 votes
0 answers
210 views

Modularity switching for primes $p>7$

In Freitas, Le Hung, and Siksek's 2014 paper proving that elliptic curves over totally real quadratic fields are modular they prove (and use) the following result (Theorems 3 and 4): let $\bar \rho_{E,...
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11 votes
1 answer
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Roadmap for studying Galois deformation theory/modularity theorems from a modern perspective

I am a graduate student with some background in Galois deformation theory. I am familiar with the basics (the existence of a universal deformation space with prescribed conditions) and with some ...
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4 votes
0 answers
499 views

Modern example of a reciprocity law and intuition behind it

I'm very new to the Langlands program and I was going through the Gauss reciprocity law, Hilbert's 9th problem, Artin's reciprocity law which allowed him to identify the Artin's L-functions with the ...
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