Lundi 17 Novembre 2025, 11:00 à IPHT, Salle Claude Itzykson, Bât. 774	IPHT-MAT (Séminaire de matrices, cordes et géométries aléatoires)	physics
Giuseppe Di Giulio ( Stockholm University )	Local Quenches from a Krylov Perspective
Abstract:	Résumé/abstract: In the last few years, quantifying the complexity of quantum states has found applications in many fields, including quantum information and computing, quantum dynamics in many-body systems, and black hole physics. Among these measures, the spread complexity roughly quantifies the size of the space of states visited along quantum dynamics. It is obtained through Krylov space methods, which consist of projecting the evolution of a state onto one-dimensional dynamics. In this talk, I will discuss the evolution of the spread complexity after a local quantum quench in conformal field theories (CFT). Interestingly, this quantity depends on the central charge of the considered theory. I will also show that, to get rid of all the non-universal contributions in the leading time behaviour, it is convenient to study another Krylov space quantity, the K-entropy, an entropy measure defined for pure states without the need for a bipartition. These results support the usefulness of the Krylov space methods to study quantum dynamics.

Mardi 18 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
Thibault Scoquart ( LPT Toulouse/LPTMC )	TBA

Mardi 18 Novembre 2025, 11:00 à LPTHE, LPTHE library	SEM-LPTHE (Séminaire du LPTHE)	hep-th
Salvatore Raucci ( IFT Madrid )	AdS vacua of non-supersymmetric strings
Abstract:	The non-supersymmetric string landscape remains largely unexplored, lacking the systematic tools provided by the supergravity equations. In this talk, I will discuss cases where the equations of motion of tachyon-free, non- supersymmetric string theories can be recast as algebraic conditions. Focusing on the ten-dimensional SO(16)×SO(16) heterotic string, I will then present a systematic framework based on a fictitious Kaluza-Klein reduction, yielding AdS4 solutions on cosets G/H with H-valued gauge fields.

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

Mercredi 19 Novembre 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
Raj Patil ( MPI Potsdam & Humboldt Universität Berlin )	Precision Gravity: Gravitational Waves using Feynman Diagrams
Abstract:	Observations of gravitational waves (GW) have the potential to unravel the mysteries of cosmic origins, constrain the equations of state of compact objects, and serve as a test of general relativity. To achieve these scientific goals, it is crucial to develop highly precise and accurate waveform templates to minimize systematic errors. My talk will focus on computing state-of-the-art effective two-body Hamiltonians and fluxes using techniques from quantum field theory and scattering amplitudes. These Hamiltonians and fluxes serve as fundamental building blocks for waveform templates, and dictate the accuracy of the waveform model. In particular, I will describe the effects of spinning and tidally deformed compact objects on evolution of the binary system. I will present computations of the linear-in-spin Hamiltonian at 4.5 post-Newtonian (PN) order, as well as the quadratic-in-spin Hamiltonian at 5PN order. Furthermore, I will describe oscillation modes of neutron stars (NS) induced by tidal interactions, particularly the fundamental-mode dynamical tides, which are expected to play a crucial role in constraining the NS equation of state in upcoming GW observing runs. I will discuss the computation of fluxes up to 2PN for adiabatic tidal interactions and effective Hamiltonians up to 3PN for both dynamic and adiabatic tidal interactions. The latter is particularly interesting as it requires introducing counterterms to remove divergences, leading to a renormalization group flow of the post-adiabatic Love number.

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 )	Detecting particle-like interactions via coherently enhanced decoherence
Abstract:	Elusive particles, such as sub-GeV dark matter candidates or even the well-known neutrinos that decoupled one second after the Big Bang, may have evaded detection due to the tiny energy they deposit in detectors. Even when detected, experiments with energy thresholds are only sensitive to the high-q^2 region of the scattering rate, which is not the dominant contribution for many scenarios, such as dark- matter interactions mediated by long-range forces or low-momentum transfers that are Born-enhanced. In this talk, I will discuss the potential of atom interferometers to probe such particle-like interactions through an open-quantum-system framework and how this approach applies to dark matter searches. I will provide examples in which quantum-mechanically enhanced phase-shifts — induced collectively by the multiple atoms in the interferometer — could be tested in the laboratory. I will end by highlighting new, promising observables for discovering physics beyond the Standard Model.

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 )	Hamiltonian Cobordism
Abstract:	I will discuss states charged under global symmetries detected by the Cobordism Conjecture in Quantum Gravity theories and examine when such states can be realized as smooth, finite-energy configurations in asymptotically flat spacetime. Assuming standard energy conditions on the stress-energy tensor, I will show that no such regular configurations exist when the relevant bordism generators fail to admit a metric of positive scalar curvature. For such symmetries, the charged states should therefore be singular, involve quantum matter that violates energy conditions or collapse the asymptotically flat spacetime. Such global symmetries are therefore not manifest in the IR. I will outline the implications of this for symmetries detected by spin bordism. Finally, I will consider the bordism groups of spin manifolds with positive scalar curvature and argue that they detect approximate global symmetries in the IR. Such symmetries are broken in the UV but from the low-energy perspective they signal the need to include energy condition-violating matter. Based on WIP with M. Montero and G. Tazzoli

Vendredi 21 Novembre 2025, 15:00 à ESPCI, Room Charpak, entrance building, ground floor, 10 rue Vauquelin, Paris ( Zoom link available at seminaires-lpem@espci.fr )	SEM-EXCEP (Seminaire exceptionnel)	cond-mat
Andrew Millis ( Columbia University and the Flatiron Institute )	Magnetic, metal-insulator and superconducting transitions in Moire transition metal dicalcogenides
Abstract:	One unit cell thick layers of materials such as WSe$_2$ may be stacked one on top of the other at a small relative twist angle, creating a Moire' pattern characterized by a large unit cell. The resulting electronic structure is characterized by a nontrivial quantum geometry, interaction strength set by device configuration, and in-situ tunable electron density and band theory. The systems exhibit metallic, superconducting, fermi surface reconstructed (likely antiferromagnetic), and insulating phases. The unprecedented tunabilty allows a systematic experiment-theory comparison, enabling insights into the Mott transition, electronically mediated superconductivity and fundamental questions of transport in interacting electron systems. This talk reports will summarize recent experimental and theoretical work related to these questions. References: Nature 637, 839-845 (2025), PRR 6 033127 (2024), arXiv:2408.16075, arXiv:2412.14296, arXiv:2503.11763 arXiv:2506.22325 and to appear

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, 11:00 à IPHT, Salle Claude Itzykson, Bât. 774	IPHT-MAT (Séminaire de matrices, cordes et géométries aléatoires)	physics
Valerio Scarani	A quantum wheel of fortune
Abstract:	Abstract: In this talk I shall review the work done in the past few years, inspired by a previously unnoticed observation by Tsirelson [1]: the Wigner negativity of some states of a single harmonic oscillator can be certified by measuring only one observable (say, position) at one among a set of suitable times. This is somewhat surprising, as it is common knowledge that the evolution of a harmonic oscillator is identical to the classical one in the Heisenberg representation.  We improved the characterization of the original protocol for continuous variables and extended it to discrete variables [2,3], the latter case leading to the first experimental implementation [4]. We also modified the protocol to detect entanglement: for continuous variables, it gives an entanglement witness that is free of false positives [5]; for discrete variable, we reported the first witness that detects the GHZ state of N spins using only measurements of the total angular momentum [6,7]. On a more foundational level, the task being operational, it can be phrased in the language of generalized probabilistic theories: contrary to what happens for Bell inequalities, here quantum theory can always reach the maximal score [8] References: [1] B. Tsirelson, https://arxiv.org/abs/quant-ph/0611147 [2] L.H. Zaw et al., Phys. Rev. A 106, 032222 (2022) https://arxiv.org/abs/2204.10498 [3] L.H. Zaw, V.S., npj Quantum Information 11, 152 (2025) https://arxiv.org/abs/2411.03132 [4] A. Vartjees et al., Newton 1, 100017 (2025) https://arxiv.org/abs/2410.07641 [5] P. Jayachandran et al., Phys. Rev. Lett. 130, 160201 (2023) https://arxiv.org/abs/2210.10357 [6] K.-N. Huynh-Vu et al., Phys. Rev. A 109, 042402 (2024) https://arxiv.org/abs/2311.00806 [7] J. Chen et al., Phys. Rev. A 110, 062408 (2024) https://arxiv.org/abs/2410.07641[8] L.H. Zaw et al. Phys. Rev. Lett. 134, 190201 (2025) https://arxiv.org/abs/2401.16147

Lundi 24 Novembre 2025, 14:00 à LPNHE, Charpak	LPNHE (Séminaires du LPNHE)	physics
Baptiste Ravina ( LPTHE )	Toponium at the LHC: a new frontier in top-quark physics
Abstract:	The top quark, the heaviest known elementary particle, has long been thought unable to form bound states. However, intriguing hints in recent LHC data suggest that toponium, a short-lived quasi-bound state of a top-antitop pair, might have left observable traces in data and possibly even been discovered. In this seminar, we will discuss why toponium is a unique laboratory for studying the theory of the strong interaction in the non-relativistic regime and how modern theoretical techniques allow bound-state effects to be incorporated into state-of-the-art collider simulations. We will then review experimental signatures that could reveal the presence of toponium in current and future LHC data and finally, highlight recent ATLAS measurements showing an excess of events near threshold consistent with toponium formation, compare them with CMS results and theoretical expectations, and outline prospects for further investigation. Together, this will offer a comprehensive overview of the current status and future directions for using toponium as a new window into the physics of the top quark.

Lundi 24 Novembre 2025, 15:00 à LPTHE, LPTHE library	SEM-LPTHE (Séminaire du LPTHE)	hep-th
Jani Kastikainen ( University of Würzburg )	Driven inhomogeneous CFT as a theory in curved space-time
Abstract:	Driven quantum systems exhibit a large variety of interesting and sometimes exotic phenomena. In this talk, for two-dimensional conformal field theories (CFTs) driven by evolving background space-time metrics in a closed universe, I present an operator formulation as a driven inhomogeneous CFT. I solve the anomalous Ward identities for the renormalized stress tensor operator of the CFT in curved space-time and show that there exists a special renormalization scheme, the chirally split scheme, in which the solution is consistent with the presence of two commuting copies of the Virasoro algebra. Based on this, I derive the Schrödinger picture Hamiltonian operator and show that unitary time-evolution of the CFT in the background metric is equivalent to unitary evolution of the inhomogeneous CFT. I discuss simple correlation functions, entanglement entropy and their scheme dependence in the curved background. Depending on time constraints, I will present the corresponding holographic dual geometry in 3D gravity extending previous results to general driving. The talk is based on arXiv:2306.00099, arXiv:2409.08319 and arXiv:2508.18350.

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.

Mardi 25 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
Vincent Ouazan-Reboul ( LPTMS )	TBA

Mercredi 26 Novembre 2025, 10:30 à IHES, Amphithéâtre Léon Motchane ( Online talk streamed at IHES )	SEED (Seed Seminar of Mathematics and Physics)	math-ph
Giuseppe Scola ( UNICAL (Università della Calabria) )	Non-trivial Fixed Point of a \psi^4_d Fermionic Theory: Anomalous Exponent and Scaling Operators
Abstract:	We consider the Renormalization Group (RG) fixed-point theory associated with a fermionic \psi^4_d model in d = 1, 2, 3 with fractional kinetic term, whose scaling dimension is fixed so that the quartic interaction is weakly relevant in the RG sense. The model is defined in terms of a Grassmann functional integral with interaction V*, solving a fixed-point RG equation in the presence of external fields, and a fixed ultraviolet cutoff. We define and construct the field and density scale-invariant response functions, and prove that the critical exponent of the former is the naive one, while that of the latter is anomalous and analytic. We construct the corresponding (almost-)scaling operators, whose two point correlations are scale-invariant up to a remainder term, which decays like a stretched exponential at distances larger than the inverse of the ultraviolet cutoff. Our proof is based on constructive RG methods and, specifically, on a convergent tree expansion for the generating function of correlations, which generalizes the approach developed by three of the authors in a previous publication (Giuliani et al. in JHEP 01:026, 2021. https://doi.org/10.1007/JHEP01(2021)026). CMP 406.10 (2025): 257, joint work with A. Giuliani, V. Mastropietro and S. Rychkov.

Mercredi 26 Novembre 2025, 10:30 à IHES, Centre de conférences Marilyn et James Simons ( Cours de l'IHES )	MATH-IHES (TBA)	math
Hong Wang ( IHES & New York University )	Union of Tubes and Kakeya Sets (3/3)
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.

Mercredi 26 Novembre 2025, 11:00 à LPENS, L378	FORUM-ENS (Forum de Physique Statistique @ ENS)	cond-mat.stat-mech
Lenart Zadnik	TBA

Mercredi 26 Novembre 2025, 11:00 à IJCLAB, 100/2-A201 - Salle A201 (IJCLab) ( https://indico.ijclab.in2p3.fr/event/12350/ )	IJCLAB-HEP (Particle Physics Seminars at IJCLab)	hep-ph
Luca Maxia ( LPTHE, Sorbonne Université )	TBA

Mercredi 26 Novembre 2025, 11:00 à IPHT, Salle Claude Itzykson, Bât. 774	IPHT-MAT (Séminaire de matrices, cordes et géométries aléatoires)	hep-th
Thomas Van Riet ( KU Leuven )	TBA
Abstract:	TBA

Mercredi 26 Novembre 2025, 11:45 à IHES, Amphithéâtre Léon Motchane	SEED (Seed Seminar of Mathematics and Physics)	math-ph
Camille Cazaux ( LPSM )	TBA

Jeudi 27 Novembre 2025, 11:00 à LPTHE, bibliothèque du LPTHE, tour 13-14, 4eme étage	SEM-DARBOUX (Séminaire Darboux - physique théorique et mathématiques)	hep-th
Fathi Ben Aribi ( IMJ-PRG )	TBA

Vendredi 28 Novembre 2025, 12:00 à LPENS, L378	ENS-BIOPHYS (ENS Biophysics Seminar)	physics.bio-ph
Vincent Oauzan-Reboul ( LPTMS )	TBA

Vendredi 28 Novembre 2025, 15:00 à LPTHE, LPTHE library	SEM-LPTHE (Séminaire du LPTHE)	hep-th
Kunal Gupta ( Uppsala )	From knots to quivers via exponential networks
Abstract:	I will present our proposal for a mirror derivation of the quiver description of open topological strings known as the knots-quivers correspondence, based on enumerative invariants of augmentation curves encoded by exponential networks. Quivers are obtained by studying M2 branes wrapping holomorphic disks with Lagrangian boundary conditions on an M5 brane, through their identification with a distinguished sector of BPS kinky vortices in the 3d-3d dual QFT. Our proposal suggests that holomorphic disks with Lagrangian boundary conditions are mirror to calibrated 1-chains on the associated augmentation curve, whose intersections encode the linking of boundaries. This is based on works arXiv:2407.08445, arXiv:2412.14901 with Pietro Longhi.

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

Mardi 2 Décembre 2025, 11:00 à LPTHE, LPTHE library	SEM-LPTHE (Séminaire du LPTHE)	hep-th
Godwin Martin ( ICTS Bengaluru )	TBA

Mardi 2 Décembre 2025, 11:00 à IPHT, Amphi Claude Bloch, Bât. 774	IPHT-GEN (Séminaire général du SPhT)
Jesse Thaler ( MIT )	TBA

Jeudi 4 Décembre 2025, 10:00 à IHP, Room Yvette Cauchois (Perrin building)	RENC-THEO (Rencontres Théoriciennes)	hep-th
Andrew O'bannon	TBA
Abstract:	TBA

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	TBA

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, 11:45 à IHES, Amphithéâtre Léon Motchane	SEED (Seed Seminar of Mathematics and Physics)	math-ph
Lucas Rey ( DMA, Ens )	TBA