Monday 26 October 2026, 14:30 at IHES, Amphithéâtre Léon Motchane ( Cours de l'IHES )	PT-IHES (Séminaire de physique théorique de l'IHES)	hep-th
Yin-Chen He ( Perimeter Institute & IHES )	Fuzzy Sphere Meets CFT: 3D Ising, Fermions and Gauge Theories (3/4)
Abstract:	In this series of lectures, I will introduce the "fuzzy (non-commutative) sphere regularization," a recently proposed non-perturbative approach to 3D CFTs. I will first elucidate its fundamental concepts and then dive into illustrative examples, including the 3D Ising transition, fermionic CFTs, and Chern-Simons matter theories. I will comment on the potential theoretical direction in understanding fuzzy sphere regularization from the aspect of algebra on fuzzy sphere.

Tuesday 27 October 2026, 14:00 at LPENS, LPENS Library - E239	LPENS-PH (LPENS Particle physics phenomenology and cosmology)	hep-th
Abner David Gutierrez Romero ( Turin U. )	Cusped Defects: Cusp Operator Expansion, Conformal Properties, and Bootstrap Applications
Abstract:	We analyze general properties of cusped defect lines embedded in generic conformal field theories (CFTs). We prove that suitably defined cusp scaling operators transform like primary operators under general conformal transformations. We show that, via the cusp operator expansion (COE), defects of general shape can be expanded in a basis of cusped defects. These findings are checked and exemplified in the case of the localized magnetic field defect. Finally, we derive analytic constraints on dynamical cusp data by making use of a crossing equation, and discuss possible numerical bootstrap applications of our results.

Wednesday 28 October 2026, 14:30 at IHES, Amphithéâtre Léon Motchane ( Cours de l'IHES )	PT-IHES (Séminaire de physique théorique de l'IHES)	hep-th
Yin-Chen He ( Perimeter Institute & IHES )	Fuzzy Sphere Meets CFT: 3D Ising, Fermions and Gauge Theories (4/4)
Abstract:	In this series of lectures, I will introduce the "fuzzy (non-commutative) sphere regularization," a recently proposed non-perturbative approach to 3D CFTs. I will first elucidate its fundamental concepts and then dive into illustrative examples, including the 3D Ising transition, fermionic CFTs, and Chern-Simons matter theories. I will comment on the potential theoretical direction in understanding fuzzy sphere regularization from the aspect of algebra on fuzzy sphere.

Thursday 29 October 2026, 11:00 at CPHT, Louis Michel, CPHT, Ecole polytechnique	CPHT-LLR (Colloquium de Particules et Cosmologie)	hep-ph
Carlos Lamas ( University of Santiago de Compostela )	Exploring the contribution of the initial stages to jet quenching.
Abstract:	Jets are essential probes of the hot and dense nuclear matter produced in heavy- ion collisions. While their propagation through the thermal quark–gluon plasma (QGP) has been extensively studied, their interaction with the preceding nonequilibrium stages remains less understood. Understanding these early interactions requires accounting for both the dynamics of the medium and the formation time scales associated with the jet’s initial virtuality. We first investigate the Glasma, the earliest stage of the collision, characterized by strong, nonequilibrium classical gluon fields. We develop a light-front Hamiltonian framework to describe the real-time quantum evolution of energetic probes through these fields. Within this framework, we compute their transverse momentum broadening and compare our results with calculations based on classical particle dynamics. To address the complementary question of how the initial jet virtuality affects its interaction with the medium, we develop a factorization framework that incorporates virtuality effects into jet modification calculations using standard perturbative techniques. As a first application, we calculate jet functions differential in the initial virtuality and determine the corresponding transverse momentum broadening and medium-induced radiation spectrum. These calculations provide a basis for investigating how jet virtuality influences sensitivity to the initial stages of heavy-ion collisions.

Monday 2 November 2026, 10:30 at LPTHE, LPTHE library	SEM-LPTHE (Séminaire du LPTHE)	hep-th
Anders Wallberg ( CERN and EPFL )	TBA

Monday 2 November 2026, 11:00 at IPHT, Salle Claude Itzykson, Bât. 774	IPHT-MAT (Séminaire de matrices, cordes et géométries aléatoires)	physics
Yuan Miao	The Onsager algebra in quantum lattice models
Abstract:	Abstract:The Onsager algebra plays an important role in exactly solvable models. One of the most notable examples is the solution to the 2D classical Ising model using the Onsager algebra by Lars Onsager in 1944. I will explain the appearance of the Onsager algebra in various quantum lattice models, and report the recent results on the Onsager algebra as the symmetry of the 6-vertex model at root of unity values of anisotropy. The talk is based on a series of work in arXiv: 2606.25660, 2103.14569, 2012.10224 and work in progress.

Wednesday 4 November 2026, 10:30 at IHES, Amphithéâtre Léon Motchane	SEED (Seed Seminar of Mathematics and Physics)	math-ph
Tba	TBA

Wednesday 4 November 2026, 11:00 at LPENS, E239 (Theoretical physics library)	LPENS-BQ (Balades Quantiques de le LPENS)	cond-mat.stat-mech
Marco Schiro	From non-reciprocal to active quantum matter via engineered dissipation
Abstract:	Non-reciprocal interactions and activity are ubiquitous in classical systems far from equilibrium, from living and soft matter to ecology and optics. They give rise to distinctive collective phenomena and phase transitions. In this talk, I will discuss how non-reciprocal and active dynamics can be realised in quantum systems through engineered coupling to an external environment. I will first present our results on interacting non-reciprocal fermions and their dissipative phase transitions. I will then introduce three minimal models of an active quantum particle, exploring how activity manifests in the quantum regime.

Wednesday 4 November 2026, 11:45 at IHES, Amphithéâtre Léon Motchane	SEED (Seed Seminar of Mathematics and Physics)	math
Thomas Mordant ( LMO )	TBA

Wednesday 4 November 2026, 14:00 at IJCLAB, 100/2-A201 - Salle A201 (IJCLab) ( https://indico.ijclab.in2p3.fr/event/14514/ )	IJCLAB-HEP (Particle Physics Seminars at IJCLab)	hep-ph
Jani Penttala ( IJCLab )	Energy Correlators: A New Lens on Nuclear Structure
Abstract:	A central goal of particle physics is to understand how quarks and gluons are bound together to form nucleons and nuclear matter. One promising class of observables for this task is energy correlators, which have gained renewed attention in recent years due to their clean experimental and theoretical properties. Instead of measuring individual particles, energy correlators focus on the angular distribution of the energy flow and are often less sensitive to nonperturbative final-state hadronization. In this talk, I will discuss the role of energy correlators in probing nuclear structure, focusing on transverse momentum distributions, jet substructure, and gluon saturation. I will also demonstrate how energy correlators can provide us with complementary information compared to the standard particle production cross sections and discuss their potential for advancing our understanding of nuclear structure at the LHC and the future Electron-Ion Collider.

Thursday 5 November 2026, 10:00 at IHP, Choquet Bruhat	RENC-THEO (Rencontres Théoriciennes)	hep-th
Tba	TBA

Friday 6 November 2026, 13:00 at LPENS, Conf IV	ENS-BIOPHYS (ENS Biophysics Seminar)	physics.bio-ph
Nikolas Claussen ( Princeton University )	TBA

Monday 9 November 2026, 10:30 at LPTHE, LPTHE library	SEM-LPTHE (Séminaire du LPTHE)	hep-th
Dmitri Bykov	TBA

Monday 9 November 2026, 14:00 at IHES, Amphithéâtre Léon Motchane ( Séminaire Géométrie et groupes discrets )	MATH-IHES (TBA)	math
Antoine Song ( Caltech et IHES )	Representations and Harmonic Maps into Spheres
Abstract:	I will discuss some recent progress on harmonic maps from surfaces to spheres which are energy minimizing representatives of orthogonal representations. What can be said about their shapes and their limit geometry as the dimension of the representations grows to infinity? This is partly joint with Riccardo Caniato and Xingzhe Li.

Monday 9 November 2026, 16:00 at IHES, Amphithéâtre Léon Motchane ( Séminaire Géométrie et groupes discrets )	MATH-IHES (TBA)	math
Konstantinos Tsouvalas ( Jagiellonian University )	Combinations of Non-Archimedean Discrete Groups
Abstract:	Chatterji and Venkataramana, motivated by Nori's problem, asked for a real algebraic semisimple Lie group G and a simple Lie subgroup H of G, whether a Zariski-dense discrete subgroup of G, intersecting H in a lattice, is itself a lattice in G. After discussing what is known related to this question and Nori's problem, we will address a similar version of this question for the k-points of semisimple groups defined over a non-Archimedean local field k, and provide examples for which a positive answer fails. This is based on a combination theorem for discrete subgroups of matrix groups over discretely valued fields. We will also discuss a construction of non-Fuchsian hyperbolic groups that quasi-isometrically embed as subgroups of matrix groups over a discretely valued field.

Thursday 12 November 2026, 11:00 at LPTHE, bibliothèque du LPTHE, tour 13-14, 4eme étage	SEM-DARBOUX (Séminaire Darboux - physique théorique et mathématiques)	hep-th
Piet Lammers ( Sorbonne )	TBA

Friday 13 November 2026, 13:00 at LPENS, Conf IV	ENS-BIOPHYS (ENS Biophysics Seminar)	physics.bio-ph
Min Wu ( Worcester Polytechnic Institute )	TBA

Wednesday 18 November 2026, 10:30 at LPTHE, LPTHE library	WORK-CONF (Workshop or Conference)	math-ph
Tba	SEED

Wednesday 18 November 2026, 11:00 at IJCLAB, 100/2-A201 - Salle A201 (IJCLab) ( https://indico.ijclab.in2p3.fr/event/14513/ )	IJCLAB-HEP (Particle Physics Seminars at IJCLab)	hep-ph
Patricia Gimeno-Estivill ( University of Jyväskylä )	Diffractive TMDs and D meson production in UPCs in the CGC formalism
Abstract:	Using the Color Glass Condensate effective theory, we study the diffractive production of a massive quark-antiquark pair accompanied by a gluon in coherent photon-nucleus collisions at high energy. This partonic configuration provides the leading twist contribution to the cross section in the correlation limit where two of the partons are hard and nearly back to back in the transverse plane, while the third one is semi-hard, with a transverse momentum of the order of the nuclear saturation momentum. We consider two scenarios: (i) a hard quark-antiquark pair together with a semi-hard gluon; in this case we demonstrate transverse momentum dependent (TMD) factorisation with a mass-dependent "hard" factor and the standard expression for the gluon diffractive TMD, and (ii) a hard antiquark-gluon pair and a semi-hard quark; in this case we find TMD factorisation with a mass-independent "hard" factor and a mass-dependent quark diffractive TMD, which represents a new result. Additionally, based on these results we present a preliminary phenomenological study of diffractive D0 meson production in UPCs at LHC.

Wednesday 18 November 2026, 11:45 at LPTHE, LPTHE library	WORK-CONF (Workshop or Conference)	math-ph
Tba	SEED

Thursday 19 November 2026, 10:00 at IHP, Choquet Bruhat	RENC-THEO (Rencontres Théoriciennes)	hep-th
Max Wiesner ( Hamburg University )	TBA

Tuesday 24 November 2026, 10:45 at 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
Léo Touzo ( U. Chicago )	TBA

Wednesday 25 November 2026, 11:00 at LPTHE, LPTHE library	SEM-LPTHE (Séminaire du LPTHE)	hep-th
Claudia Rella ( IHES )	TBA

Thursday 26 November 2026, 11:00 at IHES, Amphithéâtre Léon Motchane	MATH-IHES (TBA)	math
Marco Volpe ( University of Mainz )	The Stratified Shape
Abstract:	In this talk, I will try to address the question of how to do algebraic topology with stratified spaces and schemes in a meaningful way. I will begin by recalling and motivating some of the main historical attempts to approach this question, both in topology and in algebraic geometry, passing through the work of Nash, Quinn, Siebenmann, Edwards–Hastings, Deligne, and, more recently, Lurie and Barwick–Glasman–Haine. I will then propose my own answer, based on a construction I call the stratified shape. Time permitting, I will discuss some applications of the stratified shape to proper homotopy theory (joint with Georg Lehner), homology manifolds (joint with Markus Land), and a generalization of Lurie's exodromy equivalence (joint with Peter Haine and Guglielmo Nocera).

Monday 30 November 2026, 10:30 at LPTHE, LPTHE library	SEM-LPTHE (Séminaire du LPTHE)	hep-th
Fiona Seibold ( EPFL )	TBA

Tuesday 1 December 2026, 10:45 at 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
Bo Han ( Cologne )	TBA

Wednesday 2 December 2026, 10:30 at IHES, Amphithéâtre Léon Motchane	SEED (Seed Seminar of Mathematics and Physics)	math-ph
Tba	TBA

Wednesday 2 December 2026, 11:45 at IHES, Amphithéâtre Léon Motchane	SEED (Seed Seminar of Mathematics and Physics)	math-ph
Tba	TBA

Thursday 3 December 2026, 10:00 at IHP, Yvette Cauchois	RENC-THEO (Rencontres Théoriciennes)	hep-th
Tba	TBA

Friday 4 December 2026, 13:00 at LPENS, Salle Camille Marbo, 29 ULM	ENS-BIOPHYS (ENS Biophysics Seminar)	physics.bio-ph
Matthias Merkel ( CPT Marseille, Turing Center for Living Systems )	TBA