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) )	First passages, survival probabilities & higher-dimensional convex hulls
Abstract:	First I will present joint work with B. de Bruyne and S. Redner, on first-passage resetting, where the resetting of a random walk to a fixed position is triggered by a first-passage event of the walk itself. We define an optimization problem that is controlled by first-passage resetting: a cost is incurred whenever the particle is reset and a reward is obtained while the particle stays near the reset-trigger point. We derive the condition to optimize the net gain in this system, namely, the reward minus the cost. I will also talk about an extension of first-passage resetting into a minimalist dynamical model of wealth evolution and wealth sharing among N agents. Second, I will present joint work with G. Uribe Bravo and D. Zaporozhets. We focus on the convex hull of a single multidimensional random walk, with i.i.d. steps taken from any symmetric, continuous distribution. We investigate the persistence of vertices and faces on the hull. In particular we show that the corresponding distributions are universal, and follow three regimes closely linked to the Sparre Andersen theorem for one dimensional random walks. Third, time-permitting (hence, probably not...), I will turn to the convex hull of several multidimensional Gaussian random walks. Explicit formulas for the expected volume and expected number of faces are derived in terms of the Gaussian persistence probabilities. Special cases include the already known results about the convex hull of a single Gaussian random walk and the d-dimensional Gaussian polytope. References: de Bruyne, B., R.-F., J., Redner, S. (2020). Phys. Rev. Letters, 125(5), 050602 de Bruyne, B., R.-F., J., Redner, S. (2021). J. Stat. Mech., 2021(10), 103405 R.-F., J., Zaporozhets, D. (2024). J. Math. Sc., 281(1) R.-F., J., Uribe Bravo, G., Zaporozhets, D. to appear (2026)

Mardi 9 Décembre 2025, 11:00 à LPTHE, LPTHE library	SEM-LPTHE (Séminaire du LPTHE)	hep-th
Adrien Molines ( ETH )	A novel integrable spin chain from non-AdS holography
Abstract:	Jordanian deformations offer rare integrable realisations of non-AdS holography, whose solvability methods differ from conventional AdS/CFT examples. In this talk, I will review the construction of Homogenous Yang-Baxter (HYB) deformations of worldsheet sigma-models, together with their conjectured holographic gauge duals. This leads to consider Drinfel’d twisted spin chains, for which I will present a universal treatment of their integrability. I will then single out the Jordanian HYB-deformation and its corresponding non-compact spin chain, which displays novel features in the landscape of integrable spin chains. I will present how to solve its spectrum, highlighting how integrability enables this computation in an unconventional way. Finally, I will demonstrate how the chain’s spectrum matches with the deformed string spectrum at the one-loop level and to subleading order in the long chain limit. This provides us with the first nontrivial quantum test of Jordanian non-AdS holography.

Mardi 9 Décembre 2025, 14:00 à LPENS, L378	LPENS-PH (LPENS Particle physics phenomenology and cosmology)	hep-th
Godwin Martin ( ICTS Bangalore )	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. The talk will be based on the following papers: 2403.10654, 2403.10604, 2509.03656.

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 )	Three-point functions in critical loop models
Abstract:	In two-dimensional models of critical non-intersecting loops, we conjecture an exact formula for three-point functions of fields that insert legs (open loop segments) and can have nonzero conformal spin. The conjecture extends a previous result for diagonal fields, recently proved by Ang-Cai-Sun-Wu, who also proved our conjecture for three spinless two-leg operators. We discuss in details the supporting evidence for our general conjecture coming from transfer-matrix computations using the unoriented Jones-Temperley-Lieb algebra.

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 IJCLAB, 114	IJCLAB-PTH (Particle Theory Seminar of IJCLAB Orsay)	hep-ph
Gustavo Burdman ( University of Sao Paulo )	Signals of Low Temperature Baryogenesis
Abstract:	We explore models of baryogenesis at temperatures below the electroweak scale. In particular, we focus on a realization which makes clear the connection between low temperature baryogenesis and highly displaced vertices. The model involves the out of equilibrium decay of Majorana fermions at post-sphaleron temperatures. We present the phenomenological constraints from flavor, neutron oscillations and collider physics. We detail predictions for the displaced vertex phenomenology at various facilities either approved of being proposed. Finally, we present a version of the model where baryon number is spontaneously broken, and explore the phenomenology associated with the resulting pNGB.

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, 11:00 à CPHT, Salle Louis Michel, CPHT, Ecole polytechnique	CPHT-LLR (Colloquium de Particules et Cosmologie)	hep-ph|hep-th
Hao Chen ( MIT )	Quantum Scaling in Energy Correlators: Perturbative and Non-perturbative Aspects
Abstract:	The pattern of energy flow offers important information to understand underlying dynamics in collider physics. Energy correlators are natural observables to quantify these patterns. The past few years have witnessed interesting developments of using energy correlators in the collinear limit as a phenomenological tool to probe dynamics across different colliders. In this talk, I will review the collinear factorization of energy correlators in perturbative QCD and introduce the light-ray operator product expansion formalism. We generalize this framework to describe both hadronization corrections in the pre- confinement (perturbative) regime as well as the post-confinement (free hadron) regime. Based on these results, we will propose a conjecture formula for the collinear EEC.

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

Jeudi 11 Décembre 2025, 14:30 à IHES, Amphithéâtre Léon Motchane	PT-IHES (Séminaire de physique théorique de l'IHES)	hep-th
Wei Li ( Boston University )	Holography and Large Spin Effective Field Theory for Multi-particle States
Abstract:	In this talk, I will show how to construct a holographic effective theory for the leading-twist multi-particle operators for O(2) CFT in d=3 and d=4-\epsilon. For d=4-\epsilon Wilson-Fisher fixed point. We obtain the Hamiltonian of the theory and show that it correctly reproduces all the dimensions at order \mathcal{O}(\epsilon^2) of the leading twist operators for all values of the charge Q and spin J. For d=3 strongly coupled O(2) CFT, we find excellent agreement with Q=3,4 bootstrap data and inversion formula.

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

Mardi 16 Décembre 2025, 14:00 à LPTHE, Library ( In the library, and Zoom link https://cern.zoom.us/j/63031219326? pwd=STlDY2l0UTZOTWd3Ty8zaWVQSzNTdz09 )	LPTHE-PPH (Particle Physics at LPTHE)	hep-ph
Julien Froustey ( Valencia University )	Neutrino flavor instabilities in dense astrophysical environments: when, where, what?
Abstract:	Accurately modeling neutrino flavor oscillations in global simulations of core- collapse supernovae or neutron star mergers remains a major challenge, albeit a potentially crucial one for making reliable predictions. Indeed, it is now widely recognized that flavor instabilities—in which classically computed neutrino distributions are dramatically altered when including quantum effects—must occur commonly in such environments. In this talk, I will focus on the case of binary neutron star mergers, and specifically discuss so-called "fast" and "collisional" instabilities, trying to answer a few questions. Where and when do they occur? What are their consequences? To address the latter point, a promising strategy is the development of subgrid models of neutrino flavor transformation. In this approach, insights from detailed studies of local quantum neutrino transport are used to formulate effective prescriptions that modify classical neutrino distributions, enabling their incorporation into large-scale simulations. I will thus discuss recent progress on determining the asymptotic states reached after the onset of a flavor instability, a key ingredient for such subgrid models.

Mardi 16 Décembre 2025, 15:00 à LPTHE, LPTHE library	SEM-LPTHE (Séminaire du LPTHE)	cond-mat.dis-nn
Damien Barbier ( EPFL )	TBA

Mardi 16 Décembre 2025, 15:00 à IHES, Centre de conférences Marilyn et James Simons ( Séminaire Laurent Schwartz EDP et applications )	MATH-IHES (TBA)	math
Xiao Ma ( University of Michigan )	An Introduction to the Wave Kinetic Theory

Mercredi 17 Décembre 2025, 11:00 à LPENS, L378	FORUM-ENS (Forum de Physique Statistique @ ENS)	cond-mat.stat-mech
Zohar Nussinov ( Washington University in St. Louis )	TBA

Jeudi 18 Décembre 2025, 10:00 à IHP, Amphi Darboux	RENC-THEO (Rencontres Théoriciennes)	hep-th
Markus Dierigl ( CERN )	The importance of being discrete
Abstract:	In this talk I will highlight the importance of discrete data in gauge and gravitational theories. In particular I will describe the classification of deformation classes of spacetime manifolds equipped with these discrete structures (such as discrete gauge fields). These are important for the determination of (topological) global symmetries and anomalies of the underlying theory. In case of quantum gravity theories we expect all global symmetries to be absent and an inclusion of certain defects is required. Finally, I will also describe a strategy to bound allowed discrete gauge symmetries in theories of quantum gravity.

Jeudi 18 Décembre 2025, 11:00 à IJCLAB, Bld. 210, Theory Seminar Room (114)	IJCLAB-PTH (Particle Theory Seminar of IJCLAB Orsay)	hep-ph
Lukas Allwicher ( DESY )	Cornering New Physics through precision measurements at FCC-ee
Abstract:	A future high-intensity e+e- collider running at the Z-pole, while not achieving high energies, offers great potential for BSM explorations through indirect effects. The prospected 6x10^12 Z bosons which would be produced on-shell would not only result in a leap in precision for traditional electroweak observables, but are an excellent heavy flavour factory as well. At the same time, experimental runs above the Z resonance up to the tt-threshold will offer different and complementary insights. We explore the implications of precision measurements at FCC-ee in the search for heavy new physics, both within an EFT approach and in explicit models.

Jeudi 18 Décembre 2025, 11:30 à IHP, Amphi Darboux	RENC-THEO (Rencontres Théoriciennes)	hep-th
Oscar Varela ( utah state university, ift madrid )	TBA

Lundi 5 Janvier 2026, 11:00 à IPHT, Salle Claude Itzykson, Bât. 774	IPHT-MAT (Séminaire de matrices, cordes et géométries aléatoires)	physics
Rémy Mahfouf	La FK-percolation presque critique en milieu aléatoire
Abstract:	Nous étudions la percolation FK où les paramètres des arêtes sont choisis comme des variables aléatoires indépendantes dans le régime proche-critique. Nous montrons que si ces paramètres satisfont une condition naturelle de centrage autour du point critique, alors le modèle quenched présente typiquement un comportement critique à des échelles bien plus grandes que la longueur caractéristique déterministe. Plus précisément, dans une boîte de taille N, si le modèle homogène avec un paramètre d?arête déterministe p a un comportement critique dans le régime |p ? pc| ? W, alors le modèle quenched avec des paramètres d?arête aléatoires p qui satisfont typiquement |p ? pc| ? W^{1/3} a encore un comportement critique. Nous traitons également le cas particulier de la percolation de Bernoulli, où nous montrons que si l?on commence par échantillonner des paramètres d?arêtes aléatoires indépendants non dégénérés centrés autour de 1/2, puis une configuration de percolation sur ces arêtes, le modèle quenched  est presque sûrement critique à grande échelle. Basé sur un travail avec Emile Avérous, disponible sur arXiv 2509.08938.