Séminaire Amplitudes et Gravitation sur l’Yvette (IHES/IPhT)
The S-matrix bootstrap is a non-perturbative framework that exploits general physical principles such as unitarity, analyticity, and crossing symmetry to constrain scattering amplitudes and gain insights into strongly interacting dynamics where perturbation theory fails. I will briefly review the state of the art of the modern bootstrap and motivate the need for a new framework that incorporates multi-particle unitarity. I will then describe the Atkinson-Mandelstam method and explain how deep-learning techniques enable its practical realization. Finally, I will present some of the results obtained using this approach.
 
Pour être informé des prochains séminaires vous pouvez vous abonner à la liste de diffusion en écrivant un mail à sympa@listes.math.cnrs.fr avec comme sujet: « subscribe seminaire_physique PRENOM NOM »(indiquez vos propres prénom et nom) et laissez le corps du message vide.

Séminaire Amplitudes et Gravitation sur l’Yvette (IHES/IPhT)
We study scattering on the Coulomb branch of planar N=4 SYM.  At weak ‘t Hooft coupling scattering amplitudes can be computed using Feynman diagrams and the relevant degrees of freedom are quarks and gluons. At strong ‘t Hooft coupling the dynamics is captured by string scattering in flat space.  Dual conformal symmetry makes it possible to constrain the unitarity properties and the spectrum of the amplitude: bound states are encoded in the cusp anomalous dimension of a Maldacena-Wilson line with operators inserted at the cusp, which is fixed by integrability.  In this talk, we show how to combine dual conformal invariance, integrability, worldsheet bootstrap and the S-matrix bootstrap to explore scattering at finite ‘t Hooft coupling.  [Based on 2510.19909]
 
Pour être informé des prochains séminaires vous pouvez vous abonner à la liste de diffusion en écrivant un mail à sympa@listes.math.cnrs.fr avec comme sujet: « subscribe seminaire_physique PRENOM NOM »(indiquez vos propres prénom et nom) et laissez le corps du message vide.

Running Seminar
I will explain how to find Hodge points on the bases of Calabi-Yau families together with the respective Hodge cycles in their fibers by looking at their mod p reductions.
========
Pour être informé des prochains séminaires vous pouvez vous abonner à la liste de diffusion en écrivant un mail à sympa@listes.math.cnrs.fr avec comme sujet: « subscribe seminaire_mathematique PRENOM NOM »(indiquez vos propres prénom et nom) et laissez le corps du message vide.

Seed Seminar of Mathematics and Physics
The conformal block expansion of correlation functions is a fundamental tool in the bootstrap program. Block computation can be related to a specific class of harmonic functions on the conformal group. We generalise this concept to the case of thermal conformal field theories and compute one-point blocks for spinning representations in three dimensions. Specifically, we derive a universal Casimir equation and solve it using recursion relations. Finally, we use the blocks in several examples to explore some features of OPE coefficients.
 
========
Pour être informé des prochains séminaires vous pouvez vous abonner à la liste de diffusion en écrivant un mail à sympa@listes.math.cnrs.fr avec comme sujet: « subscribe seminaire_mathematique PRENOM NOM »(indiquez vos propres prénom et nom) et laissez le corps du message vide.

Seed Seminar of Mathematics and Physics
Tensor network renormalization group (RG) is a powerful technique providing great control over the renormalization group flow both numerically and analytically. This talk will focus on the study of fixed points of tensor network RG maps in the context of classical lattice models (e.g., the Ising model). Studying fixed points allows one to retrieve information about phase transitions in a system, which motivates this research. I will first introduce basic tensor network concepts. Then, I will present some rigorous results about high- and low-temperature fixed points of lattice spin models (based on arXiv:2107.11464, 2210.06669, and 2401.04229). Finally, I will discuss the recent development that may grant access to the critical fixed points of lattice systems (based on arXiv:2408.10312).
 
========
Pour être informé des prochains séminaires vous pouvez vous abonner à la liste de diffusion en écrivant un mail à sympa@listes.math.cnrs.fr avec comme sujet: « subscribe seminaire_mathematique PRENOM NOM »(indiquez vos propres prénom et nom) et laissez le corps du message vide.

Seed Seminar of Mathematics and Physics
Anti-de Sitter space acts as an infra-red cutoff for asymptotically free theories, allowing interpolation between a weakly-coupled small-sized regime and a strongly-coupled flat-space regime. I will discuss this interpolation in the context of Yang-Mills theories in AdS from the perspective of boundary conformal theories and its implications for the confinement/deconfinement transition. We find indications that at the transition a singlet scalar operator becomes marginal, destabilizing the deconfined phase existing at a small size and leading to a confined phase that smoothly connects to flat space.
 
========
Pour être informé des prochains séminaires vous pouvez vous abonner à la liste de diffusion en écrivant un mail à sympa@listes.math.cnrs.fr avec comme sujet: « subscribe seminaire_mathematique PRENOM NOM »(indiquez vos propres prénom et nom) et laissez le corps du message vide.

Seed Seminar of Mathematics and Physics
I will present a concrete construction of 2d Ising partition functions on lattice, with non-abelian (more generally non-invertible) global symmetry. The construction realizes the Ising model as the boundary theory of a 3d symmetry topological field theory (SymTFT) with specific boundary conditions. Suitable choices of boundary conditions correspond to going to different topological sectors of the global symmetry or gauging arbitrary non-anomalous subsymmetry. Electric-magnetic type duality of the SymTFT results in dual descriptions of the Ising model that generalizes the Kramers-Wannier duality of Z/2Z symmetric Ising models.
 
========
Pour être informé des prochains séminaires vous pouvez vous abonner à la liste de diffusion en écrivant un mail à sympa@listes.math.cnrs.fr avec comme sujet: « subscribe seminaire_mathematique PRENOM NOM »(indiquez vos propres prénom et nom) et laissez le corps du message vide.

Seed Seminar of Mathematics and Physics
Non-equilibrium dynamics of isolated quantum many-body systems plays an important role in contemporary theoretical physics research, from foundational questions on quantum statistical mechanics to the development of quantum technologies.I will provide a guided tour of a selection of results on thermalization and ergodicity breaking in quantum many-body dynamics, with an eye on mathematically rigorous studies, including (many) conjectures and (few) proven statements.  
========
Pour être informé des prochains séminaires vous pouvez vous abonner à la liste de diffusion en écrivant un mail à sympa@listes.math.cnrs.fr avec comme sujet: « subscribe seminaire_mathematique PRENOM NOM »(indiquez vos propres prénom et nom) et laissez le corps du message vide.

Seed Seminar of Mathematics and Physics
Our understanding of the behaviors appearing in statistical physics has been built firstly on the well-known Ising Model. Here, we will consider a disordered version of the one-dimensional Ising model: we will present and study the ferromagnetic Ising model on a line graph interacting with an external magnetic field, sampled from an i.i.d. distribution. We will be interested in the regime where the intensity of the disorder is fixed and the spin-spin interaction goes to infinity.
We will also introduce a continuous version of the model, which naturally arises from a weak disorder limit. For this continuous model, various quantities (such as the free energy) can be computed explicitely, thus yielding precise information on the typical configurations of the system.
The free energy of the discrete model can easily be expressed as the Lyapunov exponent of a random product of 2×2 matrices, which we estimate using Furstenberg’s theory: we will present recent results on the asymptotics of the free energy, in the regime we consider.
Furthermore, in both the discrete and the continuous models, we will caracterise the behaviour of the system at the level of configurations. In agreement with predictions in the physics literature, we will show that the configurations are typically close to one given configuration, determined by the environment (the external field), thus showing that the disorder is strongly relevant.
Our discussion will concern mainly the critical case, i.e., the case where the disorder is centered, but we may also address the non-critical case.
 
========
Pour être informé des prochains séminaires vous pouvez vous abonner à la liste de diffusion en écrivant un mail à sympa@listes.math.cnrs.fr avec comme sujet: « subscribe seminaire_mathematique PRENOM NOM »(indiquez vos propres prénom et nom) et laissez le corps du message vide.

Seed Seminar of Mathematics and Physics
Hydrodynamics is one of the oldest example of field theories, describing the long-range behaviour of many-body systems and its study remained mostly classical. Nevertheless, near zero temperature, quantum fluctuations grow in importance raising the natural question: is there a consistent quantum picture of a perfect fluid at zero temperature? In this talk, I will review the subtly inequivalent Lagrangians realizations of the perfect fluid through the lens of modern effective field theory (EFT). I will then discuss its particularity, naming the presence of an infinitely dimensional symmetry. As we will see, its main implication is the existence of transverse modes with vanishing dispersion relation at the classical level, and an infinitely degenerate spectrum and UV-IR mixing at the quantum level. This is based on a work with G. Cuomo, E. Firat, B. Henning and R. Rattazzi https://arxiv.org/abs/2412.10344.
========
Pour être informé des prochains séminaires vous pouvez vous abonner à la liste de diffusion en écrivant un mail à sympa@listes.math.cnrs.fr avec comme sujet: « subscribe seminaire_mathematique PRENOM NOM »(indiquez vos propres prénom et nom) et laissez le corps du message vide.

Seed Seminar of Mathematics and Physics
Introduced by Polyakov in the 1980s, Liouville quantum gravity (LQG) is in some sense the canonical model of a random fractal Riemannian surface. LQG can be defined as a path integral over fields corresponding to the Liouville action, or equivalently as a random metric measure space that turns out to describe the scaling limit of a host of two-dimensional discrete objects. In particular, certain discrete conformal embeddings of random planar maps converge to canonical (up to conformal reparametrization) embeddings of LQG surfaces into 2D Euclidean space. Though one might expect these metric embeddings to retain some vestige of conformality, in fact no embedding of an LQG surface into Rn can be quasisymmetric. This generalizes a result of Troscheit in the special case of sqrt(8/3)-LQG (corresponding to uniform random planar maps). Time permitting, I will also discuss future directions in the study of metric embeddability for LQG.
The zoom link is available by subscribing to the mailing list: sympa@listes.math.cnrs.fr
========
Pour être informé des prochains séminaires vous pouvez vous abonner à la liste de diffusion en écrivant un mail à sympa@listes.math.cnrs.fr avec comme sujet: « subscribe seminaire_mathematique PRENOM NOM »(indiquez vos propres prénom et nom) et laissez le corps du message vide.

Seed Seminar of Mathematics and Physics
On large classes of closed even-dimensional Riemannian manifolds M, we construct and study the Copolyharmonic Gaussian Field, i.e. a conformally invariant log-correlated Gaussian field of distributions on M. This random field is defined as the unique centered Gaussian field with covariance kernel given as the resolvent kernel of Graham—Jenne—Mason—Sparling (GJMS) operators of maximal order. The corresponding Gaussian Multiplicative Chaos is a generalization to the 2m-dimensional case of the celebrated Liouville Quantum Gravity measure in dimension two. We study the associated Liouville Brownian motion and random GJMS operator, the higher-dimensional analogues of the 2d Liouville Brownian Motion and of the random Laplacian. Finally, we study the Polyakov–Liouville measure on the space of distributions on M induced by the copolyharmonic Gaussian field, providing explicit conditions for its finiteness and computing the conformal anomaly.J. London Math. Soc. (2) 2024:110, 1-80, joint work with Ronan Herry, Eva Kopfer, Karl-Theodor Sturm.
The zoom link is available by subscribing to the mailing list: sympa@listes.math.cnrs.fr
========
Pour être informé des prochains séminaires vous pouvez vous abonner à la liste de diffusion en écrivant un mail à sympa@listes.math.cnrs.fr avec comme sujet: « subscribe seminaire_mathematique PRENOM NOM »(indiquez vos propres prénom et nom) et laissez le corps du message vide.