Lundi 1 Décembre 2025, 14:00 à LPNHE, Charpak	LPNHE (Séminaires du LPNHE)	physics
Constance Ganot ( IP2I )	Twins Embedding

Mardi 2 Décembre 2025, 10:45 à LPTMC, campus Jussieu, couloir 12-13, 5ème étage, salle 5-23	SEM-LPTMC (Séminaire du Laboratoire de Physique Théorique de la Matière Condensée)	cond-mat
Guido Giachetti ( ENS )	Integrable Dynamics and Thermalization in the Quantum O(n) Model at Large n
Abstract:	The quantum O(n) model has long served as a valuable framework for studying both equilibrium and dynamical properties of quantum many-body systems. In this talk, we investigate its non-equilibrium dynamics following a quantum quench in the large-n limit. While the model is known to be tractable in this regime, we show that it is in fact integrable - with integrals of motions stemming from that of the classical Neumann model - thus enabling a complete analytical solution of its dynamics. This integrability reveals a synchronization mechanism that gives rise to persistent oscillations, interpretable as Higgs modes localized at the edge of the spectral band. We further demonstrate that the long-time behavior is governed by a Generalized Gibbs Ensemble (GGE), in contrast to previous expectations, and we obtain exact critical exponents differing from those commonly reported. Remarkably, integrability persists even in the presence of long-range couplings, allowing us to explore the crossover between mean-field and genuinely many-body regimes in terms of parametric Floquet resonances of the microscopic degrees of freedom.

Mardi 2 Décembre 2025, 11:00 à DPT-PHYS-ENS, amphi Jaurès - 29 reu d'Ulm 75005 PARIS	COLLOQUIUM-ENS (Colloquium of the Physics Department of ENS)	physics
Hugo Duminil-Copin ( Université de Genève et IHES, lauréat de la médaille Fields 2022 )	Large-scale behaviour of the four-dimensional φ⁴ model
Abstract:	In this talk, we will discuss the scaling limits of spin fluctuations in four-dimensional Ising-type models with nearest-neighbor ferromagnetic interaction at or near the critical point are Gaussian and its implications from the point of view of Euclidean Field Theory.

Mardi 2 Décembre 2025, 11:00 à LPTHE, LPTHE library	SEM-LPTHE (Séminaire du LPTHE)	hep-th
Godwin Martin ( ICTS Bengaluru )	An Exterior Field Theory for Hawking Radiation
Abstract:	How should one understand the physics of field theories living around a black hole? We know since Einstein that black holes suck in everything that is thrown at them (dissipation into the black hole). But since Hawking, we also know that black holes radiate (Hawking fluctuations of the black hole). Can one set up a field-theoretic description in the exterior of a black hole accounting for both these effects? I will present an affirmative answer to this question (for an AdS Schwarzschild black brane) and try to explain how the black hole modifies the Feynman rules of the field theory outside.

Mardi 2 Décembre 2025, 11:00 à IPHT, Amphi Claude Bloch, Bât. 774	IPHT-GEN (Séminaire général du SPhT)
Jesse Thaler ( MIT )	QCD Theory meets Information Theory
Abstract:	What if we could generate synthetic data for the Large Hadron Collider based entirely on first-principles theoretical calculations?  While this dream is hopelessly out of reach, we do have a growing catalog of precision calculations in quantum chromodynamics (QCD) as a well as increasingly accurate Monte Carlo generators.  In this talk, I show how to leverage ideas from information theory and machine learning to merge these disparate QCD predictions into a unified theoretical prediction with associated uncertainties.  Our strategy highlights the importance of logarithmic moments, which have not been previously studied in the QCD literature.

Mardi 2 Décembre 2025, 14:00 à LPENS, L378	LPENS-PH (LPENS Particle physics phenomenology and cosmology)	hep-th
Alessandro Piazza ( SISSA )	Bootstrap bounds on Yang-Mills in AdS
Abstract:	Yang-Mills theory in AdS_4 with Dirichlet boundary conditions is expected to undergo a deconfinement-confinement transition as the AdS radius varies, as the global symmetry of the boundary CFT cannot hold in flat space. We apply the conformal bootstrap to four-point functions of non-abelian conserved currents in 3d to place bounds on proposed mechanisms for the transition. We rule out the scenario in which the boundary current decouples by bounding the current central charge. We also obtain bounds on the dimension of the lightest scalar operators, which disfavour a bulk-Higgs mechanism and instead support a transition triggered by a scalar singlet becoming marginal.

Mardi 2 Décembre 2025, 14:00 à LPTHE, library	LPTHE-PPH (Particle Physics at LPTHE)	hep-ph
Matteo Cerutti ( IRFU, Saclay )	Towards the next generation of TMD extractions
Abstract:	One of the central challenges in hadronic physics over the past decade has been to unravel the three-dimensional (3D) structure of the nucleon. A powerful tool for this task is provided by Transverse Momentum Distributions (TMDs), nonperturbative objects that encode the dependence of quarks and gluons on their longitudinal momentum fraction and their intrinsic transverse momentum relative to the parent hadron. By accessing TMDs through processes such as Drell–Yan lepton-pair production and semi-inclusive Deep Inelastic scattering, we can gain unprecedented insights into the quark and gluon dynamics that build nucleon structure. In this seminar, I will discuss the current status of unpolarized TMD phenomenology and present the latest results from the MAP Collaboration on flavor dependence and on a new neural-network–based approach to TMD extractions. I will also show very recent progress on combining lattice-QCD calculations with experimental data to achieve a more precise determination of nonperturbative TMD evolution. These advances are particularly relevant for future high-precision experiments such as the Electron–Ion Collider (EIC) and the high-luminosity LHC, where accurate control over TMD dynamics will be essential.

Mercredi 3 Décembre 2025, 14:00 à CPHT, Salle de Conférence Louis Michel	SEM-CPHT (Séminaire du CPHT)	hep-th
Francesco Bertucci ( University of Mississippi )	Bootstrapping Euclidean lattices
Abstract:	Using numerical bootstrap methods, we constrain the spectrum of the Laplacian operator in $d$-dimensional flat manifolds, as well as the triple integrals of its eigenmodes. We provide many examples of $d$-dimensional flat tori that populate these bounds. In certain dimensions, our bounds are saturated by some special lattices, including the $E_8$ lattice in 8d and the Leech lattice in 24d. These bounds admit an interpretation in the context of Kaluza-Klein theories and have connections with the sphere packing and kissing number problems.

Mercredi 3 Décembre 2025, 14:00 à LPTM, 4.13	SEM-LPTM-UCP (Seminaires du LPTM , Universite de Cergy Pontoise)	math-ph
Victor Buendia ( Bocconi University, Department of Computing Sciences, Milan )	Mean-field descriptions of coupled stochastic oscillators and its applications to Neuroscience
Abstract:	The celebrated Ott-Antonsen ansatz for coupled oscillators provides a useful framework for working with deterministic systems in the thermodynamic limit, but it fails to capture many features of stochastic systems. Several solutions have been recently proposed to accurately describe the behaviour of the order parameters in coupled oscillator systems. However, a fluctuating description of the order parameters at the mesoscopic scale was missing. In this talk, I will show how to derive an exact fluctuating theory for systems of coupled oscillators and its implications for theoretical neuroscience, from individual neurons to whole-brain neural mass models. The theory allows one to derive Langevin equations for the order parameters, opening the door to study features of synchronisation phase transitions and finite-size effects. In particular, I will show a novel application for quadratic integrate-and-fire (QIF) neurons. The QIF model has become an extremely powerful tool in computational neuroscience since its publication in 2015, leading to the so-called "next-generation" neural field models. However, it was limited to deterministic systems. I will present a fully stochastic version of the macroscopic description of the QIF neurons.

Mercredi 3 Décembre 2025, 14:45 à IHES, Amphithéâtre Léon Motchane ( Séminaire Amplitudes et Gravitation sur l’Yvette (IHES/IPhT) )	PT-IHES (Séminaire de physique théorique de l'IHES)	hep-th
Riccardo Gonzo ( Queen Mary University )	Regge Theory for Gravity Amplitudes
Abstract:	I will discuss the high-energy, small-angle limit of two-body classical gravitational scattering, focusing on the tower of multi-H diagrams that govern the leading logarithmic behavior. First, I will show that the recently developed SCET forward-scattering framework for gravity is fully equivalent to the multi-Regge expansion of the classical amplitude, reproducing exactly the s-channel multi-H diagrams. I will then compute the single-H diagram at two loops and the double-H diagrams at four loops, matching onto the classical eikonal phase in the ultrarelativistic limit. Finally, using dispersion relations, we establish a novel link between the high-energy logarithmic terms in the real and imaginary parts of the eikonal phase at 5PM order.

Jeudi 4 Décembre 2025, 10:00 à IHP, Room Yvette Cauchois (Perrin building)	RENC-THEO (Rencontres Théoriciennes)	hep-th
Andrew O'bannon ( SUNY Old Westbury )	Trace Anomalies of Boundaries and Defects
Abstract:	Conformal Field Theories (CFTs) in even spacetime dimensions are characterized, in part, by trace anomaly coefficients- the coefficients of curvature invariants in the (expectation value of the) trace of the stress tensor. These coefficients often appear in various physical observables, such as stress tensor correlators, thermal entropy, universal contributions to entanglement entropy, and more. Some of them also obey powerful non-perturbative constraints, such as c-theorems. However, what if the CFT has a boundary or defect? How do these change the trace anomaly? Do they produce new terms in the trace anomaly, and if so, then do these new trace anomaly coefficients appear in physical observables, and do they obey any constraints? In this talk, I will summarize the state of the art and the open questions in our understanding of boundary and defect trace anomalies, with emphasis on two- and four-dimensional boundaries and defects.

Jeudi 4 Décembre 2025, 11:30 à IHP, salle Yvette Cauchois	RENC-THEO (Rencontres Théoriciennes)	hep-th
Matthew Headrick	Mysterious properties of holographic entanglement
Abstract:	The Ryu-Takayanagi holographic entanglement entropy formula is a cornerstone of our modern understanding of holography and quantum gravity. It predicts that static holographic states have many peculiar properties, expressed as inequalities obeyed by entanglement entropies. These inequalities remain deeply mysterious, both on conceptual and technical levels. Can we decode what they’re telling us about the entanglement structure of semiclassical states in quantum gravity? For that, we need to know if the inequalities are obeyed in time-dependent states, in other words by the Hubeny-Rangamani-Takayanagi formula. This is itself a fascinating problem in general relativity. We will review the state of the art on these questions, including the attempts to resolve them and the evidence that has been gathered so far.

Jeudi 4 Décembre 2025, 14:00 à ESPCI, Room Boreau, building C, 2nd floor, 10 rue Vauquelin, ESPCI ( Zoom link available at seminaires-lpem@espci.fr )	SEM-EXCEP (Seminaire exceptionnel)	cond-mat
Antoine Borrel ( Ecole Polytechnique, Palaiseau, France )	Building up coupled systems out of quantum emitters in low dimensional materials
Abstract:	For the past two decades quantum emitters have been intensively studied to develop bright, pure and on-demand single photon sources as building blocks for quantum cryptography and computing. The now achievable high control of a single quantum emitter naturally paves the path to the development of coupled systems which would arise from quantum emitters close to each other, up to their arrangement in array with controlled symmetry, where collective effects such as super-fluorescence or super-radiance is expected. In this talk, I will present the case of quantum emitters unintentionally embedded in a carbon nanotube via chemical functionalisation close enough to each other to display some coupling, before discussing the optical control of quantum emitters located in a 2D moiré array through a quasi-resonant process involving exciton-phonon coupling.

Lundi 8 Décembre 2025, 14:00 à IHES, Amphithéâtre Léon Motchane ( Séminaire Géométrie et groupes discrets )	MATH-IHES (TBA)	math
Andrea Seppi ( Università di Torino )	Topology of Properly Convex Projective Manifolds of Dimension Four (and Higher)
Abstract:	I will present several results on the topology of closed manifolds of dimension at least 4 that admit a (real) properly convex projective structure, all related to a vanishing theorem of Kobayashi from 1984 for the rational Pontryagin classes. In arbitrary dimensions, I will outline a classification of locally symmetric manifolds admitting properly convex projective structures. Focusing on dimension 4, I will then present a result on the geometric decomposition which is the analogue of a theorem of Benoist in dimension 3, and the construction of examples that realize all possible positive values of the Euler characteristic. Based on joint work with Stefano Riolo and Leone Slavich.

Lundi 8 Décembre 2025, 16:00 à IHES, Amphithéâtre Léon Motchane ( Séminaire Géométrie et groupes discrets )	MATH-IHES (TBA)	math
Thibault Lefeuvre ( Université Paris-Saclay )	The spectrum of Anosov representations
Abstract:	: I will report on an ongoing project in collaboration with Yannick Guedes Bonthonneau and Tobias Weich. The goal of this work is to define a natural spectrum associated with Anosov representations, consisting of complex hypersurfaces in the complexified dual Cartan subalgebra. The leading hypersurface corresponds to a well-known object in the literature — the so-called critical hypersurface of the representation. To some extent, this spectrum generalizes a similar notion in the rank-one case, known as the set of Pollicott-Ruelle resonances (and the leading resonance), which is known to encode the exponential decay of correlations, among other properties. I will describe the main consequences of this spectral approach, namely the meromorphic extension (to the full complexified dual Cartan subalgebra) of dynamical zeta functions and Poincaré series associated with the representation. If time permits, I will discuss specific values of these functions, the sharp quantitative decay of correlations for the refraction flow, and the perspectives for future work.

Mardi 9 Décembre 2025, 10:45 à LPTMC, campus Jussieu, couloir 12-13, 5ème étage, salle 5-23	SEM-LPTMC (Séminaire du Laboratoire de Physique Théorique de la Matière Condensée)	cond-mat
Julien Randon-Furling ( Centre Borelli (ENS Paris Saclay) )	TBA

Mardi 9 Décembre 2025, 14:00 à LPTHE, Library ( Seminar in person in the library but also via Zoom: https://cern.zoom.us/j/63031219326? pwd=STlDY2l0UTZOTWd3Ty8zaWVQSzNTdz09 )	LPTHE-PPH (Particle Physics at LPTHE)	hep-ph
Jordan Koechler ( Torino INFN and University )	Consistency of the Galactic Center Excess with cosmological and laboratory observations via leptophilic dark matter in U(1)Li-Lj models
Abstract:	The particle nature of dark matter remains one of the most important open questions in physics. An intriguing clue is the γ-ray excess observed by Fermi-LAT toward the Galactic Center, whose spectrum resembles the expected signal from annihilating weakly interacting massive particles. However, many conventional dark matter models are now strongly constrained by direct detection and collider experiments. In this talk, I will explore a class of anomaly-free extensions of the Standard Model based on gauged lepton-number differences, U(1)Li-Lj, as well as U(1)B-L&. I will show how some of these models can simultaneously account for the Galactic Center excess, satisfy the relic abundance requirement, and remain consistent with laboratory constraints.

Mercredi 10 Décembre 2025, 10:30 à IHES, Amphithéâtre Léon Motchane	SEED (Seed Seminar of Mathematics and Physics)	math-ph
Jesper Jacobsen ( LPENS, École normale supérieur )	TBA

Mercredi 10 Décembre 2025, 11:00 à IJCLAB, 100/2-A201 - Salle A201 (IJCLab) ( https://indico.ijclab.in2p3.fr/event/12422/ )	IJCLAB-HEP (Particle Physics Seminars at IJCLab)	hep-ph
Matteo Cerutti ( IRFU CEA )	Advances in TMD phenomenology with Neural Networks
Abstract:	In recent years, the extraction of Transverse Momentum Distributions (TMDs) has entered a new phase in which methodological advancements are becoming as important as new data. In this talk, I will focus on two recent key developments in TMD phenomenology. First, I will present a new neural-network–based approach for parametrizing TMDs developed within the framework of the MAP Collaboration. This approach significantly enhances the flexibility of the parametrization and reduces functional biases, allowing for a more faithful reconstruction of intrinsic transverse momentum distributions. Second, I will discuss very recent progress toward combining experimental measurements with lattice-QCD calculations to constrain the nonperturbative part of TMD evolution. This emerging synergy offers a promising path to achieving a more controlled description of the nonperturbative behaviour of the Collins-Soper kernel, where phenomenology alone typically suffers from limited sensitivity. These methodological advances are expected to play a crucial role in enabling precision TMD studies for future facilities such as the Electron-Ion Collider (EIC) and the high-luminosity upgrade of the Large Hadron Collider (LHC).

Mercredi 10 Décembre 2025, 11:45 à IHES, Amphithéâtre Léon Motchane	SEED (Seed Seminar of Mathematics and Physics)	math-ph
Lucas Rey ( DMA, Ens )	The near-critical dimer model and the sine-Gordon field
Abstract:	The study of critical models is of the more active areas of statistical mechanics. Regarding the dimer model, the convergence of the critical model towards the Gaussian free field was obtained around 25 years ago by Kenyon. More recently, perturbations of the critical model known as near-critical models have been considered, and some convergence results have been obtained, in particular for the Ising model. Convergence results have also been obtained for the near-critical dimer model, which did not allow to identify the limiting field, even though it was conjectured to be the sine-Gordon field. I will present a derivation of the limit using discrete massive holomorphy techniques, which expresses the limiting field as the solution of a certain Dirichlet problem associated with a massive Dirac operator. I will finally explain how to relate this field to the sine-Gordon field. This is based on an ongoing work with Nathanaël Berestycki and Scott Mason.

Mercredi 10 Décembre 2025, 13:30 à DPT-PHYS-ENS, ConfIV (E244) - 24 rue Lhomond 75005 PARIS	COLLOQUIUM-ENS (Colloquium of the Physics Department of ENS)	physics
Huelga	TBA
Abstract:	TBA

Jeudi 11 Décembre 2025, 11:00 à IHES, Amphithéâtre Léon Motchane	MATH-IHES (TBA)	math
Lambert A'campo ( IHES )	The de Rham Property of Automorphic Galois Representations over CM Fields
Abstract:	In joint work in progress with Hevesi, Thorne and Whitmore, we prove that automorphic Galois representations over CM fields are de Rham and have the expected Hodge--Tate weights. The novelty of our result is that we do not impose any assumptions on the residual mod p Galois representation. To achieve this, we prove a theorem on the cohomology of certain unitary Shimura varieties, which gives a bound on the maximal order of a torsion class in the lower half of degrees of cohomology. After placing this theorem in the right context and discussing its proof, I will sketch how it relates to the de Rham property of automorphic Galois representations.

Jeudi 11 Décembre 2025, 14:00 à LPTMC, Jussieu, LPTMC seminar room, towers 13-12, 5th floor, room 523	SEM-LPTMC (Séminaire du Laboratoire de Physique Théorique de la Matière Condensée)	cond-mat
Nicolas Laflorencie ( LPT Toulouse )	Two Decades of Debates on Many-Body Localization: Insights Gained and New Challenges
Abstract:	Extending Anderson localization to interacting many-body systems is a very challenging question. Despite two decades of intense research, the nature of many-body localization (MBL) remains unclear. In this talk, I will introduce the MBL problem through simple disordered interacting spin models. After reviewing key results, developments, and controversies, I will present our recent findings. First, I will discuss the role of rare events and many-body resonances, particularly their potential to destabilize MBL [1-3]. If time permits, I will also present unpublished results on out-of-equilibrium dynamics [4] that could clarify past numerical controversies and inspire new experiments. [1] Statistics of systemwide correlations in the random-field XXZ chain: Importance of rare events in the many-body localized phase, J. Colbois, F. Alet, N. Laflorencie, PRB 110, 214210 (2024). [2] Cat states carrying long-range correlations in the many-body localized phase, N. Laflorencie, J. Colbois, F. Alet, arXiv:2504.10566. [3] Long-range resonances in quasiperiodic many-body localization, A Padhan, J Colbois, F Alet, N Laflorencie, arXiv:2510.24704. [4] Beyond the imbalance: site-resolved dynamics probing resonances in many-body localization, A. Haldar, T. Scoquart, F. Alet, N. Laflorencie (2025).

Jeudi 11 Décembre 2025, 14:00 à LPTMC, campus Jussieu, couloir 12-13, 5ème étage, salle 5-23	SEM-LPTMC (Séminaire du Laboratoire de Physique Théorique de la Matière Condensée)	cond-mat
Antonio Picano ( Collège de France )	TBA

Vendredi 12 Décembre 2025, 11:00 à LPTM, 4.13	SEM-LPTM-UCP (Seminaires du LPTM , Universite de Cergy Pontoise)	cond-mat
Sergei Kruchinin ( Bogolyubov Inst. for Theoretical Physics, Kiev )	Electronic spectrum of graphene nanostructures
Abstract:	In this talk, research has been carried out on the electronic properties of nanostructured graphene. We focus our attention on trapped states of the proposed systems such as spherical and toroidal graphene quantum dots (GQDs). Using a continuum model, by solving the Dirac-Weyl equation, and applying periodic boundary conditions of two types, i.e., either with zigzag edges only or with both armchair and zigzag edges, we obtain analytical results for energy levels yielding self-similar energy bands located subsequently one after another on the energy scale. Only for the toroidal quantum dot the distribution of electron density is like Bohr atomic orbitals [1]. By carrying out a computation in the Lifshitz tight-binding one-electron model, we obtain the energy spectrum and electrical conductance of graphene, in the presence of substitutional impurity atoms, thus assessing the influence of the latter. In the weak-scattering approximation, we study specific features of the electron energy spectrum The regions of localization of electron impurity states, which arise at the edges of the spectrum and edges of the energy gap, are investigated [2,3].

Vendredi 12 Décembre 2025, 12:00 à LPENS, L378	ENS-BIOPHYS (ENS Biophysics Seminar)	physics.bio-ph
Michael Murrell ( Yale University )	TBA

Vendredi 12 Décembre 2025, 14:00 à LPENS, L378	FORUM-ENS (Forum de Physique Statistique @ ENS)	cond-mat.stat-mech
Arthur Alexandre ( EPFL, Swiss Institute of Bioinformatics )	From transport in channels to population evolution: how heterogeneities shape dynamics
Abstract:	In this seminar, I will discuss two problems where effective descriptions capture the essential mechanisms at play: one from hydrodynamics and one from population genetics. In hydrodynamics, Taylor dispersion describes the enhanced spreading of particles in a fluid due to the combined effects of diffusion and flow. We show how this phenomenon can be understood in tortuous, highly corrugated channels using an effective model that captures the main transport properties, providing insight into flows in porous media. The gut microbiota presents extensive genetic diversity shaped by its flow-dominated environment. Using a minimal model [2] incorporating flow, diffusion, and microbial growth that we extend to non-neutral mutations, we show how spatial structure and advection influence the fixation of beneficial mutants. This illustrates the interplay between flow, growth, and spatial heterogeneity in shaping microbial evolution. [1] Alexandre, A., Guérin, T. & Dean, D. S. Effective description of taylor dispersion in strongly corrugated channels. Physical Review E 111, 064124 (2025). [2] Labavić, D., Loverdo, C. & Bitbol, A.-F. Hydrodynamic flow and concentration gradients in the gut enhance neutral bacterial diversity. Proceedings of the National Academy of Sciences 119, e2108671119 (2022).

Lundi 15 Décembre 2025, 11:00 à IPHT, Salle Claude Itzykson, Bât. 774	IPHT-STA (Séminaire de Physique Statistique, CEA/Saclay)	physics
Patrick Valageas	From cosmology to statistical physics and condensed matter: Burgers and Gross-Pitaevskii equations
Abstract:	We will discuss some aspects of two dynamics, motivated from cosmology but which originally appeared in hydrodynamics, statistical physics and condensed matter, the Burgers and the Gross-Pitaevskii equations. In the first part, we will present a simple solvable case in 1D with Poisson initial conditions. In the second part, we will discuss the formation of dark matter vortices (as in superfluids).

Mardi 16 Décembre 2025, 11:00 à IHES, Centre de conférences Marilyn et James Simons ( Séminaire Laurent Schwartz EDP et applications )	MATH-IHES (TBA)	math
Zhongkai Tao ( IHES )	Flexibility of Initial Data in General Relativity

Mardi 16 Décembre 2025, 13:30 à IHES, Centre de conférences Marilyn et James Simons ( Séminaire Laurent Schwartz EDP et applications )	MATH-IHES (TBA)	math
Anne De Bouard ( CNRS, Polytechnique )	Gibbs Measure for the Renormalized Stochastic Gross-Pitaevskii Equation in Dimension Two