Séminaire Amplitudes et Gravitation sur l’Yvette (IHES/IPhT)
The effective-one-body (EOB) approach is a powerful formalism that maps the two-body problem in general relativity into the motion of a single body in an effective metric. EOB-based models are nowadays providing fast and accurate gravitational wave (GW) templates for comparable-mass coalescing compact binaries, namely the sources observed by the currently operating GW detectors. Third-generation detectors will instead allow us to detect signals from different sources, among which are black hole binaries with a larger mass ratio, which require a dedicated modelling. After briefly introducing the EOB formalism, I will discuss past and ongoing efforts in adapting an EOB waveform model in order to efficiently describe the evolution of large-mass-ratio binaries.
 
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Studying quantum field theories (QFTs) in anti-de Sitter (AdS) space naturally leads to boundary correlation functions that satisfy all the axioms of the conformal bootstrap. Upon taking the radius of the AdS space to infinity, one expects to recover flat space physics. We use this idea to extract bounds on the flat space S-matrix by taking the appropriate limit of numerical conformal bootstrap bounds.
 
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Energy plays a ubiquitous role in physics, and many physical classical field theories obey pointwise energy conditions. However, for QFTs, the study of energy is both richer and more precarious. In this talk, I will derive new families of quantum null energy inequalities (QNEIs), i.e. bounds on integrated null energy, in QFTs in both two and higher dimensions. These are state-independent lower bounds on localised integrals of the stress tensor, and the first of this kind for interacting theories in higher dimensions. These results are new, fundamental constraints on null energy in all quantum field theories. The proofs will include ingredients from field theory and quantum information: the quantum null energy condition (QNEC), strong subadditivity of von Neumann entropies, defect operator expansions, and the vacuum modular Hamiltonians of null intervals and strips.
 
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Balzan Conference on Open Issues in Gravitation    March 24-26, 2026    at IHES – Marilyn and James Simons Conference Center    How to get to IHES

The Balzan Conference on Open Issues in Gravitation is part of the research project carried out at IHES with the 2021 Balzan Prize for Gravitation: Physical and Astrophysical Aspects, awarded to T. Damour.
Though gravity is the oldest investigated interaction both observationally and theoretically, it remains mysterious and challenging in many aspects.This three-day conference will bring together leading experts in a wide range of topics related to gravitation. Besides offering an overview of the status of the field, the talks will address open issues in gravitation that are currently the focus of intense research, such as: gravitational waves, tests of  General Relativity, numerical relativity, self-force, new approaches to Black Hole perturbations, extreme black holes, BMS, post-Minkowskian gravity, scattering amplitudes, high-energy scattering, effective field theory, etc.
The talks will be videotaped, thereby completing the collection of Balzan Lectures at IHES (available on carmin.tv)
 

 
Organizing Committee:
Thibault Damour (IHES), Alessandro Nagar (INFN, Torino), Julio Parra Martinez (IHES)
Chairmen:
Luc Blanchet (CNRS-Institut d’Astrophysique de Paris), Gabriele Gionti (Specola, Vatican), Mikhail Volkov (Université de Tours)
Invited speakers:

Simone Albanesi (Friedrich-Schiller University Jena)

Zvi Bern (UCLA)

Donato Bini (IAC, CNR, Rome)

Marie-Anne Bizouard (ARTEMIS, Nice)

Alessandra Buonanno (Max-Planck Institute, Potsdam)
Manuela Campanelli (Rochester Inst. Tech.) – REMOTE

Alba Grassi (Université de Genève & CERN)

Marc Henneaux (International Solvay Institutes & Collège de France)

Gustav U. Jakobsen (Humbolt U., Berlin & Max Planck Inst., Potsdam)

Carlos Lousto (Rochester Inst. Tech.)

Simon Maenaut (Niels Bohr Institute, Copenhagen)

Pierpaolo Mastrolia (University of Padova) 
Keefe Mitman (Cornell University)

Ugo Moschella (Insubria U., Como & INFN, Milano)

Alessandro Nagar (INFN, Torino)
Julio Parra-Martinez (IHES)

Harvey Reall (University of Cambridge)

Jorge Santos (University of Cambridge) – REMOTE
Chiara Toldo (Université Libre de Bruxelles)
Filippo Vernizzi (IPhT, Saclay)
Niels Warburton (University College, Dublin)

 

Séminaire Laurent Schwartz — EDP et applications
 

Séminaire Laurent Schwartz — EDP et applications
 

Séminaire Laurent Schwartz — EDP et applications
 

The aim of this workshop is to bring together mathematicians and computer scientists around some talks on recent results from statistics, machine learning, and more generally data science research. Various topics in machine learning, optimization, deep learning, optimal transport, fairness, statistics will be presented. This workshop is particularly intended for doctoral and post-doctoral researchers.
 
Registration is free and open until March 27, 2026.
Invited speakers:Richard Combes (CentraleSupéléc)Hugo Cui (CNRS, Paris-Saclay)Ekhine Irurozki (Télécom Paris)Anna Korba (ENSAE)Paul Mangold (École polytechnique)Tabea Rebafka (AgroParisTech)
Organizers: Avetik Karagulyan (CNRS) & Erwan Le Pennec (École polytechnique)

Each living animal or human originates from a single cell, which divides several times, then cells differentiate and robustly self-organize into tissues and organs. This talk will discuss mechanisms governing such tissue development. Forces, shapes, movements, shape changes, all obey the laws of mechanics. But cellular materials (made of cells tiling the space) have peculiar mechanical properties.Our example is the Drosophila metamorphosis: within a few days, the fly strikingly changes from a rather simple maggot shape to a refined adult shape with wings, legs, antennas, waist, neck, and compound eyes. We film the fly’s dorsal structure (the thorax, see Figure), and its wing. We characterize quantitatively each geometrical or topological change at cell scale: cell divisions, cell neighbour changes, cell size and shape changes, and programmed cell deaths. Our unified description respects tensorial symmetry and is thus built to be valid in any dimension. It enables us to coarse-grain the discrete description, at the cell scale, to link it with a continuum mechanics description, which encompasses the information useful at the tissue scale. Such rigorous multi-scale
approach applies to a large class of disordered systems, including aggregates of living cells, or collectively migrating cells.In addition, measuring mechanical stresses in situ in the developing tissues evidences unexpected interplays between patterns of tissue elongation, cell division and mechanical stress. The complex regulation of tissue morphology, based on feedbacks betwen physics and genetics, is the subject of active researches: open questions and perspectives will be presented.

 

In 1970 Matiyasevich, building on earlier work of Davis–Putnam–Robinson, proved that every enumerable subset of $mathbb{Z}$ is Diophantine, thus showing that Hilbert’s 10th problem is undecidable for $mathbb{Z}$. The problem of extending this result to the ring of integers of number fields (and more generally to finitely generated infinite rings) has attracted significant attention and, thanks to the efforts of many mathematicians, the task has been reduced to the problem of constructing, for certain quadratic extensions of number fields $L/K$, an elliptic curve $E/K$ with $rk(E(L))=rk(E(K))>0$.  In this talk I will explain joint work with Peter Koymans, where we use Green–Tao to construct the desired elliptic curves, settling Hilbert 10 for every finitely generated infinite ring.
 
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Atttention : La première Leçon aura lieu à l’IMO, Amphithéâtre Yoccoz, le 11 mars de 10h à 12h
Retrouvez toutes ces informations sur le site de la Fondation Mathématique Jacques Hadamard :
https://www.fondation-hadamard.fr/fr/evenements/cours-avances/
Abstract:
We will discuss some recent work around the geometric Langlands program. Specific topics will depend on audience interest, but I hope to introduce the subject generally, discuss some parts of the proof of geometric Langlands in characteristic 0, give partial results in characteristic p, and discuss some arithmetic applications.
 

Atttention : La première Leçon aura lieu à l’IMO, Amphithéâtre Yoccoz, le 11 mars de 10h à 12h
Retrouvez toutes ces informations sur le site de la Fondation Mathématique Jacques Hadamard :
https://www.fondation-hadamard.fr/fr/evenements/cours-avances/
Abstract:
We will discuss some recent work around the geometric Langlands program. Specific topics will depend on audience interest, but I hope to introduce the subject generally, discuss some parts of the proof of geometric Langlands in characteristic 0, give partial results in characteristic p, and discuss some arithmetic applications.