Pantheon SEMPARIS Le serveur des séminaires parisiens Paris

The SEMPARIS seminar webserver hosts annoucements of all seminars taking place in Paris area, in all topics of physics, mathematics and computer science. It allows registered users to receive a selection of announcements by email on a daily or weekly basis, and offers the possibility to archive PDF or Powerpoint files, making it available to the scientific community.   [ More information ]


Upcoming Seminars [Next 30 ]
[ scheduler view ]

Thursday 20 June 2019, 10:00 at IHP, Salle 314 RENC-THEO (Rencontres Théoriciennes) cond-mat.str-el|hep-th
Anton Kapustin ( Caltech ) Thermal Hall conductance as a relative topological invariant, or detecting gravitational anomalies for lattice systems
Abstract: It is well-known that zero-temperature Hall conductance of a 2d system can be interpreted both as a bulk transport coefficient and a U(1) anomaly for the edge modes. The former interpretation allows one to write down a simple formula for it (Kubo formula). The latter interpretation explains why Hall conductance is a topological invariant. In this talk I will explain the difficulties in extending these considerations to thermal Hall conductance and how they are overcome. I argue that thermal Hall conductance should be regarded as an exact 1-form on the parameter space rather than a function. Another observation is that anomalies of edge modes can be interpreted in physical terms as violations of F. Bloch’s theorem about the absence of currents in an equilibrium state. Combining these observations, I show that low-temperature thermal Hall conductance of a gapped 2d system is robust under arbitrary deformations which do not close the gap.

Thursday 20 June 2019, 11:00 at IPN, Room A015 IPN-X (Séminaire commun de physique théorique des particules IPN-CPHT-X) hep-ph
Marc Schlegel ( NMSU, USA ) Transverse spin effects in the collinear twist-3 formalism
Abstract: In this talk the collinear twist-3 formalism and its application to polarized single-inclusive hard processes is discussed. The main ingredients of that formalism, i.e., collinear hadronic matrix elements of two-or three-parton operators, and their relations are introduced in detail. Then simple lepton-nucleon processes relevant for an Electron-Ion Collider (EIC) will be discussed. I will also briefly talk about a recent NLO calculation in that formalism for electron-positron annihilation.

Thursday 20 June 2019, 11:40 at IHP, 314 RENC-THEO (Rencontres Théoriciennes) hep-th
David Mateos ( U. Barcelona ) Holography at High Density
Abstract: The physics of Quantum Chromodynamics (QCD) at high density is notoriously difficult to study by conventional methods. Yet this physics will be probed by future observations of gravitational wave signals coming from neutron star mergers. I will discuss what light holography can shed on this difficult regime, paying particular attention to possible crystalline and color superconducting phases.

Friday 21 June 2019, 10:00 at IPHT, Salle Claude Itzykson, Bât. 774
( https://courses.ipht.cnrs.fr/?q=en/node/228 )
COURS (Cours) cond-mat|hep-th|physics|quant-ph
François Gélis And Grégoire Misguich ( IPhT ) Parallel programming for physicists (3/4)
Abstract: \noindent Modern computers have a growing number of processors or ``cores''. From a few units in a simple laptop, to several thousands in big servers, their number has been growing quickly over the years. But to fully take advantage of this computing power, it is necessary to have codes or softwares being able to distribute a given task over several processors working in parallel. \\ \\ These lectures will present an introduction to parallel programming in the context of scientific calculations; \par Introduction to hardware aspects (``shared'' versus ``distributed'' memory, communication between processors, vectorization, etc.) \par Solutions based on ``already-parallel'' softwares (from linear algebra libraries to highlevel computer algebra softwares) \\ \\ We will then present two widely used libraries for code parallelization, OpenMP (Open MultiProcessing) and MPI (Message Passing Interface). \\ \\ These lectures will be based on simple and concrete examples. They are intended for people with some basic programming knowledge (for instance in C/C++, Python or Fortran), but no prior experience with parallelization.
Attachments:
  • 2019_GM.pdf (8491135 bytes) OPEN

Friday 21 June 2019, 11:00 at LPTHE, Bibliothèque SEM-LPTHE (Séminaire du LPTHE) cond-mat.stat-mech
Vladimir Korobov ( JINR Dubna ) Precision theory for hydrogen molecular ions
Abstract: At present theoretical prediction for the spin-averaged frequency of ro-vibrational transitions in the hydrogen molecular ions (HMI) has reached a relative precision of $\sim\!7.5\!\times\!10^{-12}$. On the other hand, recent experiment on pure rotational transition in HD$^+$ has demonstrated the power of the Lamb-Dicke regime for precision spectroscopy of the HMI with strong potentiality in the nearest future to achieve a ppt level of spectroscopic accuracy. The Rydberg constant as it is determined in the CODATA14 adjustment of the fundamental constants has the relative uncertainty $5.9\!\times\!10^{-12}$. At the same time the two new experiments on spectroscopy of hydrogen atom performed at LKB, Paris, and MPQ, Munich, disagree in measuring the Rydberg constant by more than $3\sigma$! In our presentation we want to outline the way how the high precision results for the hydrogen molecular ions may be achieved with the help of the effective field theory --- the Nonrelativistic QED. At the very end of our talk we intend to discuss the problems, which are to be solved in order to improve (at least threefold) theoretical predictions. That will bring our theory to the level of accuracy which is better than for the present CODATA14 value of the Rydberg constant. And, we hope, that this will help to resolve the discrepancy between the LKB and MPQ experiments as well as to find answers to many other questions related to the fundamental constants.

Monday 24 June 2019, 10:45 at LPTMC, Jussieu, tower 13-12, room 5-23 SEM-LPTMC (Séminaire du Laboratoire de Physique Théorique de la Matière Condensée) cond-mat.mes-hall
Alexandre Solon ( LPTMC ) Pressure and forces in active matter
Abstract: Active matter, composed of self-propelling entities, is found across scales in nature, from cellular tissues to animal groups. Such systems, as well as engineered active materials, exhibit many types of collective behaviors and unusual mechanical properties. In this talk, I will focus on different aspects of the interactions between active fluids and boundaries or passive objects, and show that they lead to intriguing effects, specific to active systems. In particular, I will discuss the absence of equation of state for the pressure of active fluids, the instability of a filament in an active bath, long-range interactions mediated by an active fluid and the localization of active particles in a random potential.

Monday 24 June 2019, 11:00 at IPHT, Salle Claude Itzykson, Bât. 774 IPHT-PHM (Séminaire de physique mathématique) math-ph
Jean-Michel Maillet On quantum separation of variables
Abstract: A new approach to construct the separate variables basis leading to the full characterization of the transfer matrix spectrum of quantum integrable lattice models will be presented. The basis is generated by the repeated action of the transfer matrix itself on a generically chosen state of the Hilbert space. The fusion relations satisfied by the transfer matrix, stemming from the Yang-Baxter algebra properties, provide the necessary closure relations to define the action of the transfer matrix on such a basis, leading to a separate transfer matrix spectral problem. As a first example of this approach, the construction of such a basis for models associated to Y(g $\mid$ n) will be given. Then this general scheme will be applied concretely to fundamental models associated to the Y(g $\mid$ 2) and Y(g $\mid$ 3) R-matrices leading to the full characterization of their spectrum. Other examples that can be treated by this method like trigonometric spin chains, open chains with general integrable boundaries, and further higher rank cases will be briefly discussed.

Monday 24 June 2019, 13:45 at DPT-PHYS-ENS, Collège de France – 11, place Marcelin Berthelot – 75005 Paris, Room : 2 SEM-PHYS-ENS (Colloquium du Département de Physique de l'ENS) quant-ph
Pacôme Delva ( Observatoire de Paris ) Fundamental physics and geodesy with atomic clocks
Abstract: At the beginning of the 20th century the theories of special and general relativity were developed by Einstein and his contemporaries. These physical theories revolutionize our conceptions of time and of the measurement of time. The atomic clocks, which appeared in the 1950s, are so accurate and stable that it is now essential to take into account many relativistic effects. The development and worldwide comparisons of such atomic clocks allowed for some of the most stringent of fundamental physics, as well as new ideas for the search of dark matter, which I will present in this talk. On a more applied level, when taking general relativity for granted, distant comparisons of atomic clocks can be used for navigation and positioning, as well as the determination of the geopotential. I will show how the chronometric observables can fit and be used within the context of classical geodesy.

Monday 24 June 2019, 14:00 at IPHT, Salle Claude Itzykson, Bât. 774
( \\ https://www.ipht.fr/Phocea/Vie\_des\_labos/Seminaires/index.php?id=993882 )
COURS-IPHT (Cours de l'Institut de Physique Théorique) hep-th
Michele Vallisneri ( IPhT ) Le Salon Computationnel - Scientific Python for Fun and Profit (4/6)
Abstract: In the last 10 years, scientists across many fields have converged on Python as the language of choice for scientific applications; in addition to being powerful, expressive, and friendly, Python benefits from a strong ecosystem of open-source users/developers. Furthermore, the notebook interface and file format have emerged as a powerful mode for computational experimentation and for the exchange of reproducibility of studies. \par This course provides an introduction to the core Python language and to the basic ``stack'' of scientific packages. The tentative list of topics, which can later be modified according to interest and progress, is: \\ 1 - Core Python and the Python standard library; using the Jupyter notebook. \\ 2 - Numpy (arrays, broadly construed); Scipy (numerical methods). \\ 3 - Matplotlib (plotting); Pandas (data tables). \\ 4 - Object-oriented and functional Python. \\ 5 - Wrapping C/C++/Fortran; high-performance Python. \\ 6 - Sympy (symbolic calculations). \par This course won't make you into Python experts (you shouldn't expect to learn a language in a few hours!), but it will give you a sense of what is possible, of where to look for things, and of the overall spirit of the language and its community. If you wish to read ahead, here are recommended tutorials: \\ - https://docs.python.org/3/tutorial = the official language tutorial, staid but authoritative \\ - https://github.com/jakevdp/WhirlwindTourOfPython = a quick introduction to the core Python language \\ - https://jakevdp.github.io/PythonDataScienceHandbook = a thorough overview of scientific Python \par The course will consist of interactive, hands-on tutorials, lasting about 90 minues each. You are encouraged to bring your laptop, with a functional Python 3 installation. We recommend the Anaconda Distribution at https://www.anaconda.com/distribution (Python 3.7 version), which comes with all required packages. However, it is also possible to run Jupyter notebooks in the cloud, which you can do for free with a Google account at http://colab.research.google.com. \\ \\ (Organizer: IPhT/Sylvain Ribault)

Tuesday 25 June 2019, 11:00 at CPHT, Salle Louis Michel SEM-CPHT (Séminaire du CPHT) hep-th
Romain Ruzziconi ( University ULB Brussels ) The \Lambda-BMS4 group of dS4 and new boundary conditions for AdS4
Abstract: In this talk, I will discuss the solution space of general relativity in Bondi gauge, with non-vanishing cosmological constant. Using the dictionary between Bondi and Fefferman-Graham gauges, the analogues of the Bondi news, Bondi mass and Bondi angular momentum aspects at the boundary of generic asymptotically locally dS4 spacetimes will be identified. Then, I will introduce the \Lambda-BMS4 group as the residual symmetry group of Bondi gauge after boundary gauge fixing. This group consists in infinite dimensional non-abelian supertranslations and superrotations and it reduces in the asymptotically flat limit to the extended BMS4 group. Furthermore, I will present new boundary conditions for asymptotically locally AdS4 spacetimes which admit R times the group of area-preserving diffeomorphisms as the asymptotic symmetry group. (based on 1905.00971 )

Tuesday 25 June 2019, 11:00 at LPTM, 4.13 St Martin II SEM-LPTM-UCP (Seminaires du LPTM , Universite de Cergy Pontoise) math-ph
Servet Martinez ( CMM Universidad de Chile, Santiago, CHILI ) Probabilistic analysis of a discrete-time evolution in recombination.
Abstract: We study the discrete-time evolution of a recombination transformation in population genetics. The transformation acts on a product probability space, and its evolution is be described by a Markov chain on a set of partitions that converges to the finest partition. We describe the geometric decay rate to this limit and the quasi-stationary behavior of the Markov chain when conditioned to the event that the chain does not hit the limit.

Tuesday 25 June 2019, 14:00 at APC, 646A - Mondrian APC-TH (Seminar of the theory group of APC) gr-qc
Stéphane Lavignac ( IPHT, Saclay ) TBA

Tuesday 25 June 2019, 17:15 at LPENS, Salle Jaures COLLOQUIUM-ENS (Colloquium of the Physics Department of ENS) nlin
Rich Kerswell ( DAMTP, University of Cambridge ) Extracting Order from Disorder: Periodic Orbits Buried in Fluid Turbulence
Abstract: Ideas from dynamical systems have recently provided fresh insight into transitional and weakly turbulent flows. Viewing such flows as a trajectory through a phase space littered with simple invariant ('exact') solutions and their stable and unstable manifolds has proved a fruitful way of understanding such flows. Central to this approach is identifying such exact solutions directly from turbulent flow data. I will discuss amongst other things recent attempts to harness Koopman operator theory in this quest.

Wednesday 26 June 2019, 12:00 at LPENS, Conf IV FORUM-ENS (Forum de Physique Statistique @ ENS) cond-mat.stat-mech
Claudio Chamon ( Boston University ) Entanglement Spectrum Statistics as a Probe of Irreversibility and Universality in Quantum Circuits
Abstract: We study the problem of irreversibility when the dynamical evolution of a many-body system is described by a stochastic quantum circuit. In contrast to Hamiltonian evolution, energy levels are not well defined, and the well- established connection between the statistical fluctuations of the energy spectrum and irreversibility cannot be made. We show that the entanglement spectrum level statistics may provide the connection in this case. As a quantum state initialized as a product state evolves unitarily via a random quantum circuit, it generically gets asymptotically maximally entangled. Disentangling the final state is a tall order without knowledge of the exact (reverse) circuit. The entanglement spectrum level statistics, not the entanglement entropy, can capture the difficulty of finding a disentangling circuit using a Metropolis-like algorithm. We show that irreversibility corresponds to Wigner- Dyson statistics in the level spacing of the entanglement eigenvalues, and that this is obtained from a quantum circuit made from a set of universal gates for quantum computation. If, on the other hand, the system is evolved with a non- universal set of gates, the statistics of the entanglement level spacing deviates from Wigner-Dyson (e.g., Poisson distribution) and the disentangling algorithm succeeds.

Wednesday 26 June 2019, 14:00 at CPHT, Salle Louis Michel, CPHT, Ecole Polytechnique SEM-CPHT (Séminaire du CPHT) hep-th
Victoria Martin ( Arizona State University ) TBA

Wednesday 26 June 2019, 14:00 at IPHT, Salle Claude Itzykson, Bât. 774
( \\ https://www.ipht.fr/Phocea/Vie\_des\_labos/Seminaires/index.php?id=993883 )
COURS-IPHT (Cours de l'Institut de Physique Théorique) hep-th
Michele Vallisneri ( IPhT ) Le Salon Computationnel - Scientific Python for Fun and Profit (5/6)
Abstract: In the last 10 years, scientists across many fields have converged on Python as the language of choice for scientific applications; in addition to being powerful, expressive, and friendly, Python benefits from a strong ecosystem of open-source users/developers. Furthermore, the notebook interface and file format have emerged as a powerful mode for computational experimentation and for the exchange of reproducibility of studies. \par This course provides an introduction to the core Python language and to the basic ``stack'' of scientific packages. The tentative list of topics, which can later be modified according to interest and progress, is: \\ 1 - Core Python and the Python standard library; using the Jupyter notebook. \\ 2 - Numpy (arrays, broadly construed); Scipy (numerical methods). \\ 3 - Matplotlib (plotting); Pandas (data tables). \\ 4 - Object-oriented and functional Python. \\ 5 - Wrapping C/C++/Fortran; high-performance Python. \\ 6 - Sympy (symbolic calculations). \par This course won't make you into Python experts (you shouldn't expect to learn a language in a few hours!), but it will give you a sense of what is possible, of where to look for things, and of the overall spirit of the language and its community. If you wish to read ahead, here are recommended tutorials: \\ - https://docs.python.org/3/tutorial = the official language tutorial, staid but authoritative \\ - https://github.com/jakevdp/WhirlwindTourOfPython = a quick introduction to the core Python language \\ - https://jakevdp.github.io/PythonDataScienceHandbook = a thorough overview of scientific Python \par The course will consist of interactive, hands-on tutorials, lasting about 90 minues each. You are encouraged to bring your laptop, with a functional Python 3 installation. We recommend the Anaconda Distribution at https://www.anaconda.com/distribution (Python 3.7 version), which comes with all required packages. However, it is also possible to run Jupyter notebooks in the cloud, which you can do for free with a Google account at http://colab.research.google.com. \\ \\ (Organizer: IPhT/Sylvain Ribault)

Thursday 27 June 2019, 09:30 at LPTM, MIR UCP, Neuville sur Oise
( https://iea.u-cergy.fr/fr/manifestations-scientifiques/conferences-et-workhops/transport-et-dynamique-electronique-dans-du-graphene.html )
WORK-CONF (Workshop or Conference) cond-mat
G. Trambly, A. Honecker, C. Richter, K. Hricovini, L. Magaud (organizers) ( LPTM UCP; LPMS UCP; Institut Néel ) Transport et dynamique électronique dans du graphène, des dichalcogénures de métaux de transition à 2 dimensions
Abstract: Ce colloque se concentrera sur les progrès expérimentaux et théoriques récents dans le domaine du transport électronique et de la dynamique électronique de ces nanomatériaux 2D : Mono-couches de matériaux 2D, Jonctions, propriétés électroniques, Optiques et magnétiques des interfaces, Étude macroscopique d'hétéro-structures dans une configuration de dispositif Dynamique de spin dans les systèmes corrélés.

Friday 28 June 2019, 09:00 at LPTM, MIR UCP, Neuville sur Oise
( https://iea.u-cergy.fr/fr/manifestations-scientifiques/conferences-et-workhops/transport-et-dynamique-electronique-dans-du-graphene.html )
WORK-CONF (Workshop or Conference) cond-mat
G. Trambly, A. Honecker, C. Richter, K. Hricovini, L. Magaud (organizers) ( LPTM UCP; LPMS UCP; Institut Néel ) Transport et dynamique électronique dans du graphène, des dichalcogénures de métaux de transition à 2 dimensions
Abstract: Ce colloque se concentrera sur les progrès expérimentaux et théoriques récents dans le domaine du transport électronique et de la dynamique électronique de ces nanomatériaux 2D : Mono-couches de matériaux 2D, Jonctions, propriétés électroniques, Optiques et magnétiques des interfaces, Étude macroscopique d'hétéro-structures dans une configuration de dispositif Dynamique de spin dans les systèmes corrélés.

Friday 28 June 2019, 10:00 at IPHT, Salle Claude Itzykson, Bât. 774
( https://courses.ipht.cnrs.fr/?q=en/node/228 )
COURS (Cours) cond-mat|hep-th|physics|quant-ph
François Gélis And Grégoire Misguich ( IPhT ) Parallel programming for physicists (4/4)
Abstract: \noindent Modern computers have a growing number of processors or ``cores''. From a few units in a simple laptop, to several thousands in big servers, their number has been growing quickly over the years. But to fully take advantage of this computing power, it is necessary to have codes or softwares being able to distribute a given task over several processors working in parallel. \\ \\ These lectures will present an introduction to parallel programming in the context of scientific calculations; \par Introduction to hardware aspects (``shared'' versus ``distributed'' memory, communication between processors, vectorization, etc.) \par Solutions based on ``already-parallel'' softwares (from linear algebra libraries to highlevel computer algebra softwares) \\ \\ We will then present two widely used libraries for code parallelization, OpenMP (Open MultiProcessing) and MPI (Message Passing Interface). \\ \\ These lectures will be based on simple and concrete examples. They are intended for people with some basic programming knowledge (for instance in C/C++, Python or Fortran), but no prior experience with parallelization.
Attachments:
  • 2019_GM.pdf (8491135 bytes) OPEN

Friday 28 June 2019, 11:00 at APC, TBA APC-COLLOQUIUM (Colloquium de l'APC) astro-ph
Daniel Altschuler ( Puerto Rico University ) Science, Pseudoscience, and the Responsibility of Scientists
Abstract: In this presentation I outline the basic differences between Science and Pseudoscience with some examples of the latter, discuss some crucial concepts and end with a call for action by the scientific community vis-à-vis the ignorance about science and outright rejection by decision makers.

Friday 28 June 2019, 14:30 at LPENS, Conf IV LPA (Séminaire du laboratoire Pierre Aigrain) cond-mat
Julien Gabelli ( LPS, Orsay, France ) Tba
Abstract: tba

Monday 1 July 2019, 10:00 at IHES, Amphithéâtre Léon Motchane
( Cours de l'IHES )
MATH-IHES (TBA) math
Nader Masmoudi ( Université de New York ) Inviscid Limit and Prandtl System (3/4)
Abstract: One of the main open problems in the mathematical analysis of fluid flows is the understanding of the inviscid limit in the presence of boundaries. In the case of a fixed bounded domain, it is an open problem to know whether solutions to the Navier-Stokes system with no slip boundary condition (zero Dirichlet boundary condition) do converge to a solution to the Euler system when the viscosity goes to zero. The main problem here comes from the fact that we cannot impose a no slip boundary condition for the Euler system. To recover a zero Dirichlet condition, Prandtl proposed to introduce a boundary layer (a small neighborhood of the boundary) in which viscous effects are still present. It turns out that the system that governs the flow in this small neighborhood, namely the Prandtl system has many mathematical difficulties. The goal of this course is to discuss some of the recent development in the inviscid limit as well as the study of the Prandtl system. We will also discuss the singularity formation for both the stationary and non stationary Prandtl system.

Monday 1 July 2019, 11:00 at IPHT, Salle Claude Itzykson, Bât. 774 IPHT-PHM (Séminaire de physique mathématique) math-ph
Dinh-Long Vu ( IPhT ) Boundary entropy of integrable perturbed $SU(2)_k$ WZNW
Abstract: We apply the recently developped analytical methods for computing the boundary entropy, or the g-function, in integrable theories with non-diagonal scattering. We consider the particular case of the current-perturbed $SU(2)_k$ WZNW model with boundary and compute the boundary entropy for a specific boundary condition. The main problem we encounter is that in case of non-diagonal scattering the boundary entropy is infinite. We show that this infinity can be cured by a subtraction. The difference of the boundary entropies in the UV and in the IR limits is finite, and matches the known g-functions for the unperturbed $SU(2)_k$ WZNW model for even values of the level.

Monday 1 July 2019, 14:00 at IPHT, Salle Claude Itzykson, Bât. 774
( \\ https://www.ipht.fr/Phocea/Vie\_des\_labos/Seminaires/index.php?id=993884 )
COURS-IPHT (Cours de l'Institut de Physique Théorique) hep-th
Riccardo Guida ( IPhT ) Le Salon Computationnel - Scientific Python for Fun and Profit (6/6)
Abstract: In the last 10 years, scientists across many fields have converged on Python as the language of choice for scientific applications; in addition to being powerful, expressive, and friendly, Python benefits from a strong ecosystem of open-source users/developers. Furthermore, the notebook interface and file format have emerged as a powerful mode for computational experimentation and for the exchange of reproducibility of studies. \par This course provides an introduction to the core Python language and to the basic ``stack'' of scientific packages. The tentative list of topics, which can later be modified according to interest and progress, is: \\ 1 - Core Python and the Python standard library; using the Jupyter notebook. \\ 2 - Numpy (arrays, broadly construed); Scipy (numerical methods). \\ 3 - Matplotlib (plotting); Pandas (data tables). \\ 4 - Object-oriented and functional Python. \\ 5 - Wrapping C/C++/Fortran; high-performance Python. \\ 6 - Sympy (symbolic calculations). \par This course won't make you into Python experts (you shouldn't expect to learn a language in a few hours!), but it will give you a sense of what is possible, of where to look for things, and of the overall spirit of the language and its community. If you wish to read ahead, here are recommended tutorials: \\ - https://docs.python.org/3/tutorial = the official language tutorial, staid but authoritative \\ - https://github.com/jakevdp/WhirlwindTourOfPython = a quick introduction to the core Python language \\ - https://jakevdp.github.io/PythonDataScienceHandbook = a thorough overview of scientific Python \par The course will consist of interactive, hands-on tutorials, lasting about 90 minues each. You are encouraged to bring your laptop, with a functional Python 3 installation. We recommend the Anaconda Distribution at https://www.anaconda.com/distribution (Python 3.7 version), which comes with all required packages. However, it is also possible to run Jupyter notebooks in the cloud, which you can do for free with a Google account at http://colab.research.google.com. \\ \\ (Organizer: IPhT/Sylvain Ribault)

Monday 1 July 2019, 14:30 at IHES, Amphithéâtre Léon Motchane
( Cours de l'IHES )
MATH-IHES (TBA) math
Alexander Goncharov ( Yale University & IHES ) Quantum Geometry of Moduli Spaces of Local Systems and Representation Theory (2/4)
Abstract: Lectures 1-3 are mostly based on our recent work with Linhui Shen. Given a surface S with punctures and special points on the boundary considered modulo isotopy, and a split semi-simple adjoint group G, we define and quantize moduli spaces Loc(G,S) G-local systems on S, generalising character varieties. To achieve this, we introduce a new moduli space P(G, S) closely related to Loc(G,S). We prove that it has a cluster Poisson variety structure, equivariant under the action of a discrete group, containing the mapping class group of S. This generalises results of V. Fock and the author, and I. Le. For any cluster Poisson variety X, we consider the quantum Langlands modular double of the algebra of regular functions on X. If the Planck constant h is either real or unitary, we equip it with a structure of a *-algebra, and construct its principal series of representations. Combining this, we get principal series representations of the quantum Langlands modular double of the algebras of regular functions on moduli spaces P(G, S) and Loc(G,S). We discuss applications to representations theory, geometry, and mathematical physics. In particular, when S has no boundary, we get a local system of infinite dimensional vector spaces over the punctured determinant line bundle on the moduli space M(g,n). Assigning to a complex structure on S the coinvariants of oscillatory representations of W-algebras sitting at the punctures of S, we get another local system on the same spa. We conjecture there exists a natural non-degenerate pairing between these local systems, providing conformal blocks for Liouville / Toda theories. In Lecture 4 we discuss spectral description of non-commutative local systems on S, providing a non-commutative cluster structure of the latter. It is based on our joint work with Maxim Kontsevich.

Tuesday 2 July 2019, 14:00 at APC, 646A - Mondrian APC-TH (Seminar of the theory group of APC) gr-qc
José Blanco-Pillado ( IKERBASQUE, Bilbao ) TBA

Wednesday 3 July 2019, 10:00 at IHES, Amphithéâtre Léon Motchane
( Cours de l'IHES )
MATH-IHES (TBA) math
Nader Masmoudi ( Université de New York ) Inviscid Limit and Prandtl System (4/4)
Abstract: One of the main open problems in the mathematical analysis of fluid flows is the understanding of the inviscid limit in the presence of boundaries. In the case of a fixed bounded domain, it is an open problem to know whether solutions to the Navier-Stokes system with no slip boundary condition (zero Dirichlet boundary condition) do converge to a solution to the Euler system when the viscosity goes to zero. The main problem here comes from the fact that we cannot impose a no slip boundary condition for the Euler system. To recover a zero Dirichlet condition, Prandtl proposed to introduce a boundary layer (a small neighborhood of the boundary) in which viscous effects are still present. It turns out that the system that governs the flow in this small neighborhood, namely the Prandtl system has many mathematical difficulties. The goal of this course is to discuss some of the recent development in the inviscid limit as well as the study of the Prandtl system. We will also discuss the singularity formation for both the stationary and non stationary Prandtl system.

Friday 5 July 2019, 10:00 at IHES, Centre de conférences Marilyn et James Simons
( "Journée Gretchen & Barry Mazur" (https://indico.math.cnrs.fr/event/4697/) )
MATH-IHES (TBA) math
Alexander Goncharov ( Yale University & IHES ) Motivic Fundamental Group of CM Elliptic Curves and Geometry of Bianchi Hyperbolic Threefolds

Friday 5 July 2019, 11:00 at APC, Amphitheatre Pierre Gilles de Gennes APC-COLLOQUIUM (Colloquium de l'APC) astro-ph
Volodimir Savchenko ( Geneva Observatory ) TBA

Friday 5 July 2019, 11:30 at IHES, Centre de conférences Marilyn et James Simons
( "Journée Gretchen & Barry Mazur" (https://indico.math.cnrs.fr/event/4697/) )
MATH-IHES (TBA) math
Kestutis Cesnavicius ( Université Paris-Sud ) Purity for Flat Cohomology

seminars from series at institute
in subject with field matching

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