This one-day workshop is organised jointly by Huawei and IHES, as a part of the IHES-Huawei partnership. The aim of the workshop is to bring together prominent voices from academia and industry to explore the evolving role of causal reasoning in artificial intelligence. The workshop will deliver meaningful dialogue around two major directions. The first one is theory-driven causal modelling, which focuses on theoretical approaches, frameworks, and tools for understanding causality, emphasizing the development of rigorous methods to identify, estimate, and interpret causal relationships. The second topic is machine learning with causal AI and its applications, which integrates machine learning and deep learning techniques to improve causal discovery, causal inference, causal representation learning and their corresponding application fields.
INVITED SPEAKERS: 

BOWDEN Jack (Exeter University, UK)
CADEI Riccardo (EPFL, Switzerland)
FUNG Pascale (HKUST & Visiting Professor at the Central Acad. of Fine Arts in Beijing)
HENCKEL Leonard (Univ. College, Dublin, UK)
LI Haoxuan (Peking University)
LIMNIOS Myrto (EPFL, Switzerland)
TIAN Jin (MBZUAI, Abu Dhabi)
ZHOU Hong (Huawei)

 
 

 
 
Organisers: Keshuang Li (Huawei), Keli ZHANG (Huawei)

13e séminaire ITZYKSON : Bootstrap conforme et géométrie spectrale

Le 13e séminaire Itzykson est organisé par Sylvain Ribault (IPhT Saclay), Slava Rychkov (IHES) et Pierre Vanhove (IPhT Saclay). 
Depuis une dizaine d’années l’axe math-physique de la FMJH organise un séminaire Itzykson tous les ans à l’IHES. Il s’agit d’une journée consacrée à un thème de physique mathématique, avec un cours et deux ou trois exposés spécialisés (en français ou en anglais selon le choix des orateurs).
Le prochain séminaire Itzykson portera sur la théorie conforme des champs, et ses liens avec la géométrie spectrale, et la théorie des nombres. Ces sujets sont reliés par la possibilité d’appliquer une même méthode: le bootstrap conforme. Le séminaire donnera des perspectives mathématiques et physiques sur des résultats récents, notamment au sujet des spectres des variétés hyperboliques, des fonctions L en théorie des nombres, et des spectres des théories conformes.
Un cours et deux exposés auront lieu dans la journée, présentés par : 

Dalimil Mazáč, IPhT Saclay & IHES

Frédéric Naud, Sorbonne Université, IMJ-PRG
Balt van Rees, CPHT, École polytechnique

L’inscription est gratuite mais nécessaire et sera possible jusqu’au 8 octobre 2025. Un buffet-déjeuner sera offert aux participants qui s’y seront inscrits. Le séminaire sera filmé et diffusé en différé sur la chaîne YouTube de l’IHES.

We present a new structure on the first Galois cohomology of families of symplectic self-dual $p$-adic representations of $G_{Q_p}$ of rank two. This is a functorial decomposition into free rank one Lagrangian submodules encoding Bloch-Kato subgroups and epsilon factors, mirroring an underlying symplectic structure. This local sign decomposition has local as well as global applications, including compatibility of the Mazur-Rubin arithmetic local constants and epsilon factors, and new cases of the parity conjecture. It also leads to a formulation and proof of an analogue of Rubin’s conjecture over ramified quadratic extensions of $Q_p$, which initiates an integral Iwasawa theory for CM elliptic curves at primes of additive reduction. (Joint with A. Burungale, K. Nakamura, and K. Ota.)
 
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The purpose of this talk is to give fine limit theorems for the norm llgn…g1ll of a  product of random matrices, under some conditioning. These limit theorems are stated in analogy with the case of sums X1+…+Xn of real random variables. This is joint work with Ion Grama and Hui Xiao.
 

Let X be a pinched Cartan-Hadamard manifold, and Y a symmetric space of non-compact type. We define a notion of stability for coarse Lipschitz maps f : X → Y, and show that every stable map from X to Y is at bounded distance from a unique harmonic map. As an application, we extend any positive quasi-symmetric map from RP1 to the flag variety of SL(n,R), to a harmonic map from H2 to the symmetric space of SL(n,R). This allows us to define a universal Hitchin component in the style suggested by Labourie and Fock-Goncharov. This is all joint work with Peter Smillie.
 

It is well known that the observables for some classes of EFTs (eg the non-linear sigma model) naturally can be cast in terms of geometric quantities that are defined on a field space manifold.  One of the main benefits of this geometric approach is that it makes the field redefinition invariance of on-shell amplitudes manifest.  However, the standard approach does not apply to general EFTs; additionally, the field space geometry picture breaks down when one performs field redefinitions that involve derivatives.  In this talk, I will present a proposal for how to extend the notion of field space geometry to general EFTs in such a way as to accommodate general field redefinitions.  I will introduce the framework we call “functional geometry,” and will argue that this approach lays the groundwork for many new developments towards understanding properties of EFTs that circumvents issues associated with field redefinition ambiguities.
 
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I will examine Abrikosov–Nielsen–Olesen (ANO) vortex strings in variants of Abelian Higgs models. In the large flux limit, the equations governing them simplify, and the resulting giant strings realize two sharply distinct phases. I will explore qualitative features of these strings and identify patterns in their physical properties. I’ll also discuss the spectrum of small fluctuations and the associated low energy effective action. I will end by comparing these results to features of confining strings in Yang Mills theory.
 
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Fermi liquid theory is a cornerstone of condensed matter physics. However, Landau’s Fermi liquid theory does not fit into the paradigm of effective field theory in that it is formulated in terms of a kinetic equation rather than an action. We describe a new method that leads to a field-theoretical reformulation of Landau Fermi liquid theory. In this approach, a system with a Fermi surface is described as a coadjoint orbit of the group of canonical transformations. The method naturally leads to a nonlinear bosonization of the Fermi surface. The Berry phase that the Fermi surface acquires when changing shape is shown to be given bythe Kirillov-Kostant-Souriau symplectic form on the coadjoint orbit. We show that the resulting local effective field theory captures both linear and nonlinear effects in Landau’s Fermi liquid theory. Possible extensions and applications of the theory are described.

Fermi liquid theory is a cornerstone of condensed matter physics. However, Landau’s Fermi liquid theory does not fit into the paradigm of effective field theory in that it is formulated in terms of a kinetic equation rather than an action. We describe a new method that leads to a field-theoretical reformulation of Landau Fermi liquid theory. In this approach, a system with a Fermi surface is described as a coadjoint orbit of the group of canonical transformations. The method naturally leads to a nonlinear bosonization of the Fermi surface. The Berry phase that the Fermi surface acquires when changing shape is shown to be given bythe Kirillov-Kostant-Souriau symplectic form on the coadjoint orbit. We show that the resulting local effective field theory captures both linear and nonlinear effects in Landau’s Fermi liquid theory. Possible extensions and applications of the theory are described.

Fermi liquid theory is a cornerstone of condensed matter physics. However, Landau’s Fermi liquid theory does not fit into the paradigm of effective field theory in that it is formulated in terms of a kinetic equation rather than an action. We describe a new method that leads to a field-theoretical reformulation of Landau Fermi liquid theory. In this approach, a system with a Fermi surface is described as a coadjoint orbit of the group of canonical transformations. The method naturally leads to a nonlinear bosonization of the Fermi surface. The Berry phase that the Fermi surface acquires when changing shape is shown to be given bythe Kirillov-Kostant-Souriau symplectic form on the coadjoint orbit. We show that the resulting local effective field theory captures both linear and nonlinear effects in Landau’s Fermi liquid theory. Possible extensions and applications of the theory are described.

Fractional quantum Hall states are strongly interacting states of two-dimensional electrons moving in a high magnetic field. It has recently been found, theoretically and experimentally, that fractional quantum Hall fluids accommodate a quasiparticle excitations carrying spin equal to 2. I will describe the general theoretical arguments leading to this conclusion. I will also show that the existence of this spin-2 mode explains a strange feature of the numerical data on the spectrum of quantum Hall systems on a sphere.
 
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