Organising Committee Elli Pomoni(DESY)  Bruno Le Floch (Princeton University) and Masahito Yamazaki (Kavli IPMU, University of Tokyo)

Scientific Committee: Vasily Pestun (IHES), Silviu Pufu (Princeton University), Joerg Teschner (DESY)

The Summer school on "Supersymmetric Localization and Exact Results" will be held at the Institut des Hautes Etudes Scientifiques (IHES) from July 16 to July 27, 2018. IHES is located in Bures-sur-Yvette, south of Paris (40 minutes by train from Paris).

This school is open to everybody but intended primarily for young participants, including PhD students and postdoctoral fellows.

Significant progress has been made in the study of gauge theories in the last decade. Thanks to the discovery of novel techniques and especially supersymmetric localization, the field now possesses a plethora of exact results that previously seemed unreachable.

Starting with the work of Nekrasov who computed the instanton partition function for N=2 theories in four dimensions, Pestun computed the exact partition function on a four-sphere for theories with N=2 supersymmetry. Shortly after the partition functions as well as other observables in various spacetime dimensions and compact manifolds were computed.

Our school aims in deepening the understanding of current results and at investigating which of our current methods are transferable to theories with less supersymmetry, as well as trying to increase the list of possible observables that are computable via localization.

Each week will feature three or four speakers giving one lecture per day. During the first week, in addition to these three one hour and a half lectures there will be discussion and homework sessions in the afternoon. During the second week, some of the lectures will be replaced by talks on more advanced topics.

The main lectures will cover the following topics:

Week 1: Introduction to localization, Localization of instantons and Exact results on 4d N=2 theories

Week 2:  Topological strings and matrix models, M5 brane compactifications and Zamolodchikov metric and tt^* equation

Advanced talks week 2: Chiral algebras, N=1 localization, Localization with boundaries, line operators, surface operators, relations to CFT and integrable systems

INVITED SPEAKERS:

Week 1: 1h30 per topic per day
     Francesco Benini(SISSA
     Guido Festuccia (Uppsala)
     Wolfger Peelaers(Rutgers)

Advanced talk in week 1: 2-3 hours
     Seiji Terashima (Kyoto)

Week 2: 1h30 per topic per day
     Zohar Komargodski (Stony Brook)
     Maxim Zabzine (Uppsala)

Advanced talks in the second week: 2-3 hours each
     Nikita Nekrasov (Simons Center)
     Takuya Okuda (Tokyo)
     Balt van Rees (Durham)
 

Some funding is available for young participants (more info at the bottom of the page)

With the support of

 

Organized as part of the IHÉS Lectures, this 2-weeks Summer School will be the last major scientific event of the special trimester on Non-Linear Waves that will start in the beginning of May 2016 at IHÉS. This school aims at providing an overview of recent developments in the field at this stage of the new cycle started a few years ago and to provide to post-docs and researchers in the early stage of their career working in these domains an opportunity to interact with leading experts on the subject.

Another objective is to gather researchers with different backgrounds whose research is much more converging today than 4 years ago, such as the French schools working on fluid models, on kinetic theory, dynamical systems and partial differential equations in relation to finite-dimensional Hamiltonian models or the microlocal community.

Last but not least, another objective would be the following: the advances have helped to solve classical problems from physics with new and very advanced methods based on analytical intuition thus not always understood or simply not well-known by the physicists. The idea would be to initiate a transfer to physicists interested in non linear waves phenomena and intensify the discussions on more realistic models, whether fluid, kinetic or of high-frequency waves.

We will supplement mini courses (3 hours) in the morning and plenary talks in the afternoon (40-45 minutes) during 2 weeks.

Mini course speakers:

Rupert FRANK (California Institute of Technology)
Carlos KENIG (University of Chicago)
Nader MASMOUDI (Courant Institute of Mathematical Sciences)
Benoît PAUSADER (Brown University)
Michela PROCESI (Universita di Roma 1)
Robert STRAIN (University of Pennsylvania)
Daniel TATARU (University of California at Berkeley)

Plenary talks speakers:

Stefano BIANCHINI (SISSA)
Rémi CARLES (CNRS – IMAG Montpellier)
Stephen GUSTAFSON (University of British Columbia)
Joachim KRIEGER (EPFL)
Hans LINDBLAD  (Johns Hopkins University)
Hiroshi MATANO  (School of Science, University of Tokyo)
Natasa  PAVLOVIC (University of Texas at Austin)
Robert PEGO  (Carnegie Mellon University)
Svetlana ROUDENKO (George Washington University)
Gigliola  STAFFILANI (Massachusetts Institute of Technology)
Tai-Peng TSAI (University of British Columbia)
Nicola VISCIGLIA (Universita di Pisa)
Sijue WU (University of Michigan)

Organising Committee:

Yvan MARTEL (École Polytechnique)
Frank MERLE (Université de Cergy-Pontoise & IHÉS)
Fabrice PLANCHON (Université Nice Sophia-Antipolis)
 

Crédit photographique: © CNRS Photothèque
RAJAU Benoît (UMR7538 – Laboratoire de physique des lasers (LPL), VILLETANEUSE et VRIGNAUD François (UMR6172 – XLIM – LIMOGES)

With the support of

Surprisingly, there exist connected components of character varieties of fundamental groups of surfaces in semisimple Lie groups consisting only of injective representations with discrete image. Guichard and Wienhard introduced the notion of Θ-positive representations as a conjectural framework to explain this phenomenon. I will discuss joint work with Jonas Beyrer in which we establish several geometric properties of Θ-positive representations in PO(p,q). As an application, we deduce that they indeed form connected components of character varieties.

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IHES Covid-19 regulations:

– all the participants who will attend the event in person will have to keep their mask on in indoor spaces
and where the social distancing is not possible;
– speakers will be free to wear their mask or not at the moment of their talk if they feel more comfortable
without it;
– Up to 25 persons in the conference room, every participant will be asked to be able to provide a health pass
– Over 25 persons in the conference room, every participant will be asked to provide a health pass which will
be checked at the entrance of the conference room.

==================================================================

Emergence is a major buzz word of our times. My working definition, which gives plenty of room for manoeuvre is: the appearance of many body phenomena of higher symmetry than that of the Hamiltonian and degrees of freedom at the microscopic level.

In this colloquium I will discuss a topical example – the frustrated magnetic material, spin ice. Here, to an excellent approximation a classical field theoretic description with continuous U(1) symmetry emerges from Ising like degrees of freedom. The associated quasi-particles appear to be freely moving magnetic charge – magnetic monopoles – and the system behaves as a magnetic Coulomb fluid in the grand canonical ensemble with intrinsic topological properties. With the addition of quantum fluctuations the emergent magneto-statics develops further into a complete analogue of quantum electrodynamics. I will aliment this discussion with experimental results from a wide range of systems.

https://us02web.zoom.us/j/85270888147?pwd=aXdOVXBTSmNEU00vVFE2bXhqdE5vdz09

ID de réunion : 852 7088 8147
Code secret : 276852

Recently, classification problems of gapped ground state phases attract a lot of attention in quantum statistical mechanics. We explain about operator algebraic approach to these problems.

 

Participer à la réunion Zoom
https://us02web.zoom.us/j/89796579935?pwd=Ukt3R1VxUFdORHZENHJyN0k3R3Radz09

ID de réunion : 897 9657 9935
Code secret : 459425

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 quantum_encounters_seminar PRENOM NOM »
(indiquez vos propres prénom et nom) et laissez le corps du message vide.

In this talk, we will present some recent results on the twisted dynamical zeta functions of Ruelle and Selberg on compact hyperbolic manifolds, and the Fried conjecture. This conjecture concerns the relation between the value at zero of the twisted Ruelle zeta function and a spectral invariant: the complex-valued analytic torsion.

Participer à la réunion Zoom
https://us02web.zoom.us/j/84906502454?pwd=cEtmQTE3YlJoSXdJR052dnQ5eGJNQT09

ID de réunion : 849 0650 2454
Code secret : 173945

In this talk we will focus on discrete subgroups Γ of higher rank Lie groups G whose limit set is a Lipschitz manifold, i.e. locally the graph of a Lipschitz map. This is a not-uncommon feature, verified by Zariski-dense groups, usually caused by stable geometric properties of the embedding Γ → G. We will recall several examples of such groups, specially those coming from Higher rank Teichmüller Theory. The main purpose of the lecture is to explain a recent result, in collaboration with B. Pozzetti and A. Wienhard, where we prove that the critical exponent of a specific combination of eigenvalues (only depending on the dimension of the limit set) is independent of the representation. We will also explore some of its consequences.

I will discuss some questions related to Novikov’s problem for foliations on surfaces.

The problem is the following. Let M be a 3-periodic surface and H a plane intersecting M. Which kind of curves are realized as the intersection of M and H?

This problem was formulated by Sergey Petrovitch Novikov in the 80’s. He conjectured that the « trivial » situations (periodic and integrable) are generic. I will discuss the simplest situation when M is very symmetric. In this case, with Dynnikov and Skripchenko, we prove that the first return of the foliation induced by H is an Arnoux-Rauzy interval exchange transformation. I will give some properties of these maps (results with Arnoux, Cassaigne and Ferenczi). In the most interesting situation, I will mention a work in progress with Dynnikov, Mercat, Paris-Romaskevich and Skripchenko which is supposed to solve Novikov’s conjecture.

The talk will be accessible to a broad audience.

We study finite N aspects of the O(m) × O(N-m) vector model with quartic interactions in general 2 ≤ d ≤ 6 spacetime dimensions. This model has recently been shown to display the phenomenon of persistent symmetry breaking at a perturbative Wilson-Fisher-like fixed point in d=4-ε dimensions. The large rank limit of the bi-conical model displays a conformal manifold and a moduli space of vacua. We find a set of three double trace scalar operators that are respectively irrelevant, relevant and marginal deformations of the conformal manifold in general d. We calculate the anomalous dimensions of the single and multi-trace scalar operators to the first sub-leading order in the large rank expansion. The anomalous dimension of the marginal operator does not vanish in general, indicating that the conformal manifold is lifted at finite N. In the case of equal ranks we are able to derive explicitly the scaling dimensions of various operators as functions of only d.

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IHES Covid-19 regulations:

– all the participants who will attend the event in person will have to keep their mask on in indoor spaces
and where the social distancing is not possible;
– speakers will be free to wear their mask or not at the moment of their talk if they feel more comfortable
without it;
– Up to 25 persons in the conference room, every participant will be asked to be able to provide a health pass
– Over 25 persons in the conference room, every participant will be asked to provide a health pass which will
be checked at the entrance of the conference room.

==================================================================

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.

A many-body quantum system that is continually monitored by an external observer can be in two distinct dynamical phases, distinguished by whether or not repeated local measurements (throughout the bulk of the system) prevent the build-up of long-range quantum entanglement. I will describe the key features of such “measurement phase transitions” and sketch theoretical approaches to their critical properties that make connections with topics in classical statistical mechanics, such as percolation and disordered magnetism. Finally I will discuss random tensor networks with a tree geometry. These arise in a simple limit of the measurement problem, and they show an entanglement transition that can be solved exactly by a mapping to a problem of traveling waves.

==================================================================

IHES Covid-19 regulations:

– all the participants who will attend the event in person will have to keep their mask on in indoor spaces
and where the social distancing is not possible;
– speakers will be free to wear their mask or not at the moment of their talk if they feel more comfortable
without it;
– Up to 25 persons in the conference room, every participant will be asked to be able to provide a health pass
– Over 25 persons in the conference room, every participant will be asked to provide a health pass which will
be checked at the entrance of the conference room.

==================================================================

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 quantum_encounters_seminar PRENOM NOM »
(indiquez vos propres prénom et nom) et laissez le corps du message vide.

Scattering amplitudes in quantum field theories have intricate analytic properties as functions of the energies and momenta of the scattered particles. In perturbation theory, their singularities are governed by a set of nonlinear polynomial equations, known as Landau equations, for each individual Feynman diagram. The singularity locus of the associated Feynman integral is made precise with the notion of the Landau discriminant, which characterizes when the Landau equations admit a solution. In order to compute this discriminant, we present approaches from classical elimination theory, as well as a numerical algorithm based on homotopy continuation. These methods allow us to compute Landau discriminants of various Feynman diagrams up to 3 loops, which were previously out of reach. For instance, the Landau discriminant of the envelope diagram is a reducible surface of degree 45 in the three-dimensional space of kinematic invariants. We investigate geometric properties of the Landau discriminant, such as irreducibility, dimension and degree.

Participer à la réunion Zoom
https://us02web.zoom.us/j/89109430156?pwd=NnRZNFNHMkFVOUJ5cC92bkJOeDNHQT09

ID de réunion : 891 0943 0156
Code secret : 583871

 

In this talk I will discuss the notion of a GREG — a Group Random Element Generator — which is a generalization of a random walk on a group. Roughly, a Greg is a random sequence of group elements.

Associated with a Greg one obtains a pair of Furstenberg-Poisson boundaries, the spaces of ideal futures and ideal pasts. An important property that a Greg might have is the Asymptotic Past And Future Independence. Gregs satisfying this property, namely Apafic Gregs, are very well behaved. Geodesic Flows in a negatively curved environment, as well as classical random walks on groups, give rise to Apafic Gregs. After surveying the subject, I will focus on linear representations of Gregs and the associated invariant called the Lyapunov spectrum. As it turns out, under mild assumptions the Lyapunov spectrum would be simple and continuously varying.

The talk is based on joint work with Alex Furman.

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IHES Covid-19 regulations:

– all the participants who will attend the event in person will have to keep their mask on in indoor spaces
and where the social distancing is not possible;
– speakers will be free to wear their mask or not at the moment of their talk if they feel more comfortable
without it;
– Up to 25 persons in the conference room, every participant will be asked to be able to provide a health pass
– Over 25 persons in the conference room, every participant will be asked to provide a health pass which will
be checked at the entrance of the conference room.

==================================================================