Lundi 13 Octobre 2025, 12:30 à LPENS, L378	SEM-INFOR (Séminaire informel)	cond-mat.stat-mech
Xin Sun ( Peking University )	Liouville quantum gravity and applications to 2D statistical physics
Abstract:	I will summarize the mathematical development of Liouville quantum gravity over the last two decades. Then I will explain its application to 2D statistical physics, such as the derivation of the backbone exponent for 2D percolation.

Mardi 14 Octobre 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
Luca Capizzi ( LPTMS )	Exceptional Stationary State in a Dephasing Many-Body Open Quantum System
Abstract:	The late-time dynamics of many-body systems is one of the central problems in statistical mechanics. The eventual emergence of Gibbs ensembles at late times for closed systems is usually explained using the Eigenstate Thermalization Hypothesis (ETH): it postulates, among other things, local indistinguishability of the energy eigenstates and proper statistical ensembles. Rare eigenstates that violate ETH are known as many-body scars and can affect the dynamics of the system in a non-trivial way. We investigate a related mechanism for an open quantum many-body system. In particular, we focus on a model that hosts, together with the infinite-temperature state, another additional stationary state. The latter is exceptional in many respects and plays the role of a quantum scar. We discuss the properties of the model, focusing on the fate of interfaces between the two states. We find that at late times an effective description is based on stochastic fluctuations of the interface; in particular, the scar is progressively eroded at a finite velocity, and the interface broadens diffusively. While this mechanism resembles hydrodynamics of local conserved charges, important differences are pointed out. This is a joint work with Alice Marché, Gianluca Morettini, Leonardo Mazza, and Lorenzo Gotta [Phys. Rev. Lett. 135, 020406 (2025)]

Mardi 14 Octobre 2025, 14:00 à LPENS, L378	LPENS-PH (LPENS Particle physics phenomenology and cosmology)	hep-th
Jasper Kager ( Lisbon U. )	Exact Solutions of Matrix Models and String Theories
Abstract:	String theories are generally defined through strictly perturbative, asymptotic genus expansions, and the problem of non-perturbative completion is generically challenging. Matrix models and their double-scaling limits to string theories are relatively tractable in this regard, and have seen a surge of research interest due to their connection to black hole physics and supersymmetric gauge theory. I will present a large N description of Hermitian matrix model partition functions, based on spectral geometry and resurgent analysis, that accounts for all non- perturbative physics at play and is fully background independent. I will show that resurgence requires the inclusion of both positive and negative tension D-branes, and renders this initially asymptotic large N solution well-defined. Analytic continuation to arbitrarily strong coupling requires connection formulae, which we show to be given by the topological string connection formulae of Iwaki and Mariño. These ingredients put together lead to precise matches with finite N quantities. I will then present some early results on extensions of this work to matrix model correlation functions.

Mercredi 15 Octobre 2025, 10:00 à IHES, Centre de conférences Marilyn et James Simons ( 13eme Séminaire Itzykson -- L’inscription est gratuite mais nécessaire et sera possible jusqu'au 8 octobre 2025 = https://indico.math.cnrs.fr/event/14934/ )	PT-IHES (Séminaire de physique théorique de l'IHES)	hep-th|math-ph|math.NT|math.ST
Dalimil Mazac ( IPhT Saclay & IHES )	Mathematical bootstrap: from conformal fields to L-functions
Abstract:	In this course, I will revisit the conformal bootstrap from a mathematical perspective and describe its recent applications in number theory and spectral geometry. The conformal bootstrap is an algebraic formulation of conformal field theory, valid in general dimension. While its axioms define a precise mathematical structure, realizing the corresponding objects has posed a significant challenge. The main idea presented in this course is that an almost identical structure has a natural realization in number theory, specifically in spectral theory of automorphic forms. The Hilbert space of conformal field theory becomes a direct sum of automorphic representations, and the structure constants of the operator algebra are related to L-functions. This link allows us to import the bootstrap mindset and methods into mathematics, which has led to new progress on important open problems. I will describe two recent applications: bounds on spectral gaps of hyperbolic manifolds, and subconvex bounds on L-functions. (Course given in English.) References: https://arxiv.org/abs/2111.12716 https://arxiv.org/abs/2308.11174 https://arxiv.org/abs/2508.20576

Mercredi 15 Octobre 2025, 11:00 à LPENS, L378	FORUM-ENS (Forum de Physique Statistique @ ENS)	cond-mat.stat-mech
Dmitry Kovrizhin ( LPTM Cergy )	TBA

Mercredi 15 Octobre 2025, 13:30 à IHES, Centre de conférences Marilyn et James Simons ( 13eme Séminaire Itzykson -- L’inscription est gratuite mais nécessaire et sera possible jusqu'au 8 octobre 2025 = https://indico.math.cnrs.fr/event/14934/ )	PT-IHES (Séminaire de physique théorique de l'IHES)	hep-th|math-ph|math.NT|math.ST
Frédéric Naud ( Sorbonne Université, IMJ-PRG )	Problèmes ouverts et progrès récents en géométrie spectrale hyperbolique
Abstract:	Dans cet exposé, on fera un survey des progrès récents sur la compréhension du trou spectral des surfaces hyperboliques, dans la limite de grand genre. On fera le lien avec la théorie des champs via le déterminant du laplacien dont le comportement moyen sur l'espace des modules est un des problèmes clés en théorie des cordes. On conclura sur des conjectures sur le spectre en genre "infini", inspirées par la physique du solide et les quasi-cristaux.(Exposé en français)

Mercredi 15 Octobre 2025, 15:00 à IHES, Centre de conférences Marilyn et James Simons ( 13eme Séminaire Itzykson -- L’inscription est gratuite mais nécessaire et sera possible jusqu'au 8 octobre 2025 = https://indico.math.cnrs.fr/event/14934/ )	PT-IHES (Séminaire de physique théorique de l'IHES)	hep-th|math-ph|math.NT|math.ST
Balt Van Rees ( CPHT, Ecole polytechnique )	Mathematical approaches to conformal bootstrap
Abstract:	We will review the framework of conformal field theory and explain how its operator algebra leads to a natural arena for well-posed mathematical questions with physical importance. We will present some results concerning the so-called lightcone bootstrap and discuss some important open problems. (Seminar given in English).

Jeudi 16 Octobre 2025, 11:00 à CPHT, Louis Michel	SEM-CPHT (Séminaire du CPHT)	hep-th
Mattia Cesaro ( AEI Potsdam )	Integrable deformations of dimensionally reduced gravity via auxiliary fields
Abstract:	Auxiliary field deformations of D=2 field theories, recently introduced by Ferko and Smith in the context of the Principal Chiral Model, are a powerful formalism that allows to deform a known integrable theory, while preserving its integrability properties. In this talk, I will review this formalism and present recent work on how to extend it to other field theories. In particular, I will focus on the dimensional reduction of pure gravity from D=4 to D=2 along two commuting Killing isometries. I will discuss how to obtain, via auxiliary fields, an infinite family of deformations of this model that preserves not only complete integrability, but also the rich algebraic structure underlying the undeformed model. If time allows, I will comment about the possible uplift of the D=2 model thus obtained.

Jeudi 16 Octobre 2025, 11:00 à LPTHE, bibliothèque du LPTHE, tour 13-14, 4eme étage	SEM-DARBOUX (Séminaire Darboux - physique théorique et mathématiques)	hep-th
Pierre Lairez ( INRIA )	Computing the periods of smooth projective hypersurfaces
Abstract:	The periods of a smooth complex projective hypersurface are numbers obtained by integrating holomorphic differential forms over homology cycles. These numbers are interesting because they capture algebraic invariants of the hypersurface. For instance, for algebraic curves they completely determine the isomorphism class, while for algebraic surfaces they determine the Picard group. This talk will focus on the computational aspects of periods. The first challenge is topological: periods are integrals over homology cycles, but how can we construct a basis of such cycles? The second is numerical: periods are multiple integrals, so how can we compute them with thousands of digits of precision? The last is ontological: how can we extract exact algebraic data from numerical approximations? Based on joint work with Eric Pichon-Pharabod and Pierre Vanhove.

Jeudi 16 Octobre 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
Yang Wei ( Institute of Physics, Chinese Academy of Sciences )	Tuning multiband superconductivity and quantum geometry in moiré flatband systems
Abstract:	Superconductivity in flatband systems has attracted tremendous attention in condensed matter physics. Alternating twisted multilayer graphene presents a compelling multiband system, with a coexistence of Dirac bands and flat bands, for exploring superconductivity. In this talk, I will present an observation of unconventional superconducting behaviours in the alternating twisted quadralayer graphene. We systematically quantify individual carrier density contributions for both the dispersive bands and the flat bands from Dirac spectroscopy. We further estimate the flat-band Fermi velocity and superfluid stiffness via critical current measurements. Our results demonstrate an electric field–tunable coupling strength within the superconducting phase, revealing unconventional properties with vanishing Fermi velocity and large superfluid stiffness. These phenomena, attributed to substantial quantum metric contributions mediated by Dirac band hybridization, offer new insights into the mechanisms underlying unconventional flatband superconductivity in moiré systems.

Jeudi 16 Octobre 2025, 14:15 à IPHT, Salle Claude Itzykson, Bât. 774	IPHT-MAT (Séminaire de matrices, cordes et géométries aléatoires)	hep-th
Hector Parra De Freitas ( Harvard )	TBA
Abstract:	TBA

Mardi 21 Octobre 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
Miha Srdinsek ( CEA Grenoble )	Hybrid between biologically inspired and quantum inspired many-body states
Abstract:	Deep neural networks can represent very different sorts of functions, including complex quantum many-body states. Tensor networks can also represent these states, have more structure and are easier to optimize. However, they can be prohibitively costly computationally in two or higher dimensions. In this seminar I will propose a hybrid network [1] which borrows features from the two different formalisms. I will showcase the ansatz by obtaining the representation of a transverse field quantum Ising model with a long range 1/r^6 antiferromagnetic interaction on a 10×10 square lattice. The model corresponds to the Rydberg (cold) atoms platform proposed for quantum annealing. [1] Srdinsek, Waintal, arXiv:2506.05050 (2025)

Mercredi 29 Octobre 2025, 13:30 à IHP, Amphithéâtre Darboux	SEED (Seed Seminar of Mathematics and Physics)	math-ph
Andrea Sportiello ( CNRS and LIPN, Université Sorbonne Paris Nord )	Grassmann Calculus for the combinatorics of Spanning Trees and Forests
Abstract:	TBA

Mercredi 29 Octobre 2025, 15:00 à IHP, Amphithéâtre Darboux	SEED (Seed Seminar of Mathematics and Physics)	math-ph
Sonia Boulal ( Institut Denis Poisson Université d’Orléans )	Conditioned Marked Galton-Watson trees
Abstract:	We consider a Galton–Watson tree in which each node is independently marked, with a probability that depends on its number of offspring. We give a complete picture of the local convergence of critical or subcritical marked Galton–Watson trees, conditioned on having a large number of marks. In certain cases, the limit is a randomly marked tree with an infinite spine, known as the marked Kesten tree. In other cases, the local limit is a randomly marked tree with a node having infinitely many children. This corresponds to the so-called marked condensation phenomenon. Joint work with Romain Abraham and Pierre Debs.

Mercredi 29 Octobre 2025, 16:30 à IHP, Amphithéâtre Darboux	SEED (Seed Seminar of Mathematics and Physics)	math-ph
Julien Weibel ( INRIA & ENS Paris )	Probability-graphons: limits for sequences of large dense weighted graphs
Abstract:	Networks appear naturally in a wide variety of context, including for example: biological networks , epidemics processes, electrical power grids and social networks. Most of those problems involve large dense graphs, that is graphs that have a large number of vertices and a number of edges that scales as the square of the number of vertices. Those graphs are too large to be represented entirely in the targeted applications. The idea is then to go from a combinatorial representation given by the graph to an infinite continuum representation: the graphons studied by Lovász and his co-authors. In this talk, I will present a joint work with Romain Abraham and Jean-François Delmas on probability-graphons, which are measure-valued graphons that generalises graphons to the case of weighted graphs and decorated graphs. I will explain how probability-graphons are used to define random weighted graph models, define a distance that controls convergence for those sampled graphs, and give some topological results on this distance.

Mardi 4 Novembre 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
Achille Mauri ( EPFL )	TBA

Mardi 4 Novembre 2025, 11:30 à LPTHE, LPTHE library	SEM-LPTHE (Séminaire du LPTHE)	hep-th
Matthew Blacker ( University of Cambridge )	TBA

Mercredi 5 Novembre 2025, 13:30 à DPT-PHYS-ENS, ConfIV (E244) - 24 rue Lhomond 75005 PARIS	COLLOQUIUM-ENS (Colloquium of the Physics Department of ENS)	physics
Dudovich	TBA
Abstract:	TBA

Jeudi 6 Novembre 2025, 14:00 à ESPCI, tba. ( Zoom link available at seminaires-lpem@espci.fr )	SEM-EXCEP (Seminaire exceptionnel)	cond-mat
Chaste Julien ( Université Paris-Saclay, CNRS, Centre de Nanosciences et de Nanotechnologies )	TBA
Abstract:	Tba.

Jeudi 6 Novembre 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
Jérôme Dubail ( CESQ Strasbourg )	TBA

Mercredi 12 Novembre 2025, 11:00 à LPENS, L378	FORUM-ENS (Forum de Physique Statistique @ ENS)	cond-mat.stat-mech
Maxime Debertolis	TBA

Mercredi 12 Novembre 2025, 14:00 à IHES, Amphithéâtre Léon Motchane	SEED (Seed Seminar of Mathematics and Physics)	math-ph
Vincent Viau ( LAGA, USPN )	TBA

Mercredi 12 Novembre 2025, 15:15 à IHES, Amphithéâtre Léon Motchane ( Online talk streamed at IHES )	SEED (Seed Seminar of Mathematics and Physics)	math-ph
Vladimir Narovlansky ( School of Natural Sciences, Institute for Advanced Study, Princeton, USA )	TBA

Mardi 18 Novembre 2025, 11:00 à LPTHE, LPTHE library	SEM-LPTHE (Séminaire du LPTHE)	hep-th
Salvatore Raucci ( IFT Madrid )	TBA

Mercredi 19 Novembre 2025, 11:00 à IPHT, Salle Claude Itzykson, Bât. 774	IPHT-MAT (Séminaire de matrices, cordes et géométries aléatoires)	hep-th
Sean Hartnoll ( DAMTP, Cambridge )	TBA
Abstract:	TBA

Jeudi 20 Novembre 2025, 11:00 à IJCLAB, Bld. 210, Theory Seminar Room (114) ( https://indico.ijclab.in2p3.fr/event/12040/ )	IJCLAB-PTH (Particle Theory Seminar of IJCLAB Orsay)	hep-ph
Clara Murgui ( CERN )	TBA
Abstract:	TBA

Jeudi 20 Novembre 2025, 11:30 à IHP, Salle Yvette Cauchois, Bâtiment Perrin	RENC-THEO (Rencontres Théoriciennes)	hep-th
Matilda Delgado ( Max Planck Institute for Physics, Munich )	TBA

Lundi 24 Novembre 2025, 10:30 à IHES, Amphithéâtre Léon Motchane ( Cours de l'IHES )	MATH-IHES (TBA)	math
Hong Wang ( IHES & New York University )	Union of Tubes and Kakeya Sets (1/3)
Abstract:	We discuss techniques (Cordoba argument, projection theory) to prove volume bounds on union of tubes in R^2 and R^3, with applications to the Kakeya problem. This is joint work with Josh Zahl.

Lundi 24 Novembre 2025, 15:00 à LPTHE, LPTHE library	SEM-LPTHE (Séminaire du LPTHE)	hep-th
Jani Kastikainen ( University of Würzburg )	TBA

Mardi 25 Novembre 2025, 10:30 à IHES, Amphithéâtre Léon Motchane ( Cours de l'IHES )	MATH-IHES (TBA)	math
Hong Wang ( IHES & New York University )	Union of Tubes and Kakeya Sets (2/3)
Abstract:	We discuss techniques (Cordoba argument, projection theory) to prove volume bounds on union of tubes in R^2 and R^3, with applications to the Kakeya problem. This is joint work with Josh Zahl.