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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 ]
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Wednesday 20 June 2018, 11:00 at IPHT, Amphi Claude Bloch, Bât. 774 IPHT-SEM (Séminaire du IPHT) physics
Jainendra Jain ( Penn State ) Fractional quantum Hall effect and the magic of emergence
Abstract: When electrons in two dimensions are exposed to a high magnetic field, their kinetic energy is suppressed, spin frozen, and only the Coulomb interaction term survives in the Hamiltonian. What could be simpler? We have learned during the past three decades that this system generates some of the most beautiful emergent structures in physics. It has spawned topological particles that have fractional charge and fractional statistics, and it has produced exotic states, such as fractional quantum Hall effect, emergent Fermi sea, topological superconductivity and Wigner crystals. I shall begin with a pedagogical introduction to the understanding of the essential phenomenology in terms of emergent particles called composite fermions.  I shall then report on recent progress on two topics: competition between the liquid the crystal phases, and the mechanism of fractional quantum Hall effect in the second Landau level.  This colloquium is organized in the framework of the PSI2 program "Topological phases of matter: from the quantum Hall effect to spin liquids" (Topmat) https://topmat.sciencesconf.org/

Wednesday 20 June 2018, 11:30 at IPN, Bâtiment 100, Salle A015
( $ $ )
IPN-THEO (Séminaire du groupe de physique théorique de l'IPN Orsay) nucl-th
A. Ekstr\"om ( Chalmers University of Technology, Gothenburg, Sweden ) Precision nuclear theory: advances and challenges
Abstract: A precise and accurate theoretical model of the strong interactions between protons and neutrons would provide a key to new knowledge across 20 orders of magnitude; from neutrinos to neutron stars. Despite a century of the finest efforts, a systematic and quantitative description of strongly interacting matter at low energies is still lacking. In this seminar I will present some of the recent developments and future perspectives towards a predictive theory for atomic nuclei.
Attachments:
  • 2018_06_20_A_Ekstrom.pdf (204730 bytes) OPEN

Wednesday 20 June 2018, 15:30 at IPHT, Salle Claude Itzykson, Bât. 774 IPHT-SEM (Séminaire du IPHT) physics
Christian Glattli ( Service de Physique de l'état condensé, CEA Saclay ) A Josephson relation for FQHE fractional charges
Abstract: This seminar is organized in the framework of the PSI2 program "Topological phases of matter: from the quantum Hall effect to spin liquids" (Topmat) https://topmat.sciencesconf.org/

Thursday 21 June 2018, 11:00 at IPHT, Salle Claude Itzykson, Bât. 774 IPHT-SEM (Séminaire du IPHT) physics
Frédéric Mila ( EPFL, Lausanne ) Generalization of the Haldane conjecture to SU(3)
Abstract: This seminar is organized in the framework of the PSI2 program "Topological phases of matter: from the quantum Hall effect to spin liquids" (Topmat) https://topmat.sciencesconf.org/

Thursday 21 June 2018, 14:00 at LPTM, 4.13 St Martin II SEM-LPTM-UCP (Seminaires du LPTM , Universite de Cergy Pontoise) math-ph
Anastasia Doikou ( Department of Mathematics/SMCS, Heriot Watt U. Edinburgh, Scotland, UK ) Quantum Darboux-Bäcklund transformations
Abstract: We discuss the notion of the quantum auxiliary linear problem and the associated problem of quantum Darboux-Bäcklund transformation. In this frame we derive the analogue of the classical formula that provides the hierarchy of the time components of Lax pairs at the quantum level for both closed and open integrable lattice models. Particular emphasis is given to the time part of the quantum transformation as possible connections and applications to the problem of quantum quenches as well as the time evolution of local quantum impurities are evident. A discussion on the use of Bethe states as well as coherent states for the study of the time evolution is also presented. Connections with the quantum analogue of the Zakharov-Shabat method are also discussed.

Thursday 21 June 2018, 15:30 at IPHT, Salle Claude Itzykson, Bât. 774 IPHT-SEM (Séminaire du IPHT) physics
Philippe Mendels ( Laboratoire de Physique des Solides, Orsay ) Quantum kagome spin liquids: a local view
Abstract: This seminar is organized in the framework of the PSI2 program "Topological phases of matter: from the quantum Hall effect to spin liquids" (Topmat) https://topmat.sciencesconf.org/

Thursday 21 June 2018, 16:00 at LPT, 114 LPT-PTH (Particle Theory Seminar of LPT Orsay) hep-ph
Marcos Garcia ( Rice University ) Non-thermal particle production in the early universe
Abstract: I will discuss aspects of particle production in the early universe, when neither the produced particles nor the background in which they are created are in thermal equilibrium. I will focus first on "gentle" non-thermal particle production in the context of dark matter freeze-in scenarios. Here I will show that, depending on the energy dependence of the production cross section, the present dark matter abundance may have been created right at the end of inflation, in the earliest stages of reheating, before the decay products of the inflaton have thermalized. Time permitting, I will present a statistical framework for characterizing non- adiabatic, stochastic particle production during inflation and reheating. The evolution of coarse-grained quantities, such as particle occupation numbers, can be derived from a Fokker-Planck equation. I will discuss potential implications for density perturbations from the early universe.

Friday 22 June 2018, 10:00 at IPHT, Salle Claude Itzykson, Bât. 774
( https://courses.ipht.cnrs.fr/?q=fr/node/198 )
COURS (Cours) astro-ph|hep-ph
Marco Cirelli ( LPTHE Paris ) Dark matter phenomenology (2/5)
Abstract: Dark matter constitutes about 26\% of the present matter-energy content of the Universe (84\% of the matter-only content) and is one of the fundamental ingredients that shape the evolution of galaxies and the Universe. Surprisingly enough, the nature of dark matter is still unknown, and unveiling this mystery stands out as one of the most pressing issues in cosmology and particle physics. \par The course will present a basic overview of the state of the art in dark matter physics, mostly focussing on the phenomenology rather than on the many models proposed by particle theorists to explain it. \\ \par Plan of the lectures: \\ 1) Introduction, proofs of existence, and basic properties. Possible alternatives to particle dark matter and their status. \\ 2) Mechanisms of production in the early Universe: thermal freeze-out (in particular), freeze-in, asymmetric dark matter... \\ 3) Direct detection via nuclear recoils. \\ 4) Indirect detection with cosmic rays: charged particles, gamma rays (prompt and secondary), neutrinos. \\ 5) Collider searches (and possible complementarity of the searches).
Attachments:
  • 2017-2018.pdf (4503344 bytes) OPEN
  • 2018_Cirelli.pdf (4733534 bytes) OPEN

Friday 22 June 2018, 10:30 at IHES, Centre de conférences Marilyn et James Simons
( Cours de l'IHES )
MATH-IHES (TBA) hep-th
Sergiu Klainerman ( Princeton University & IHES ) On the Mathematical Theory of Black Holes (4/4)
Abstract: The gravitational waves detected by LIGO were produced in the final faze of the inward spiraling of two black holes before they collided to produce a more massive black hole. The experiment is entirely consistent with the so called Final State Conjecture of General Relativity according to which generic solutions of the Einstein vacuum equations can be described, asymptotically, by a finite number of Kerr solutions moving away from each other. Though the conjecture is so very easy to formulate and happens to be validated by both astrophysical observations as well as numerical experiments, it is far beyond our current mathematical understanding. In fact even the far simpler and fundamental question of the stability of one Kerr black hole remains wide open. In my lectures I will address the issue of stability as well as other aspects the mathematical theory of black holes such as rigidity of black holes and the problem of collapse. The rigidity conjecture asserts that all stationary solutions the Einstein vacuum equations must be Kerr black holes while the problem of collapse addresses the issue of how black holes form in the first place from regular initial conditions. Recent advances on all these problems were made possible by a remarkable combination of geometric and analytic techniques which I will try to outline in my lectures.

Friday 22 June 2018, 11:00 at LPTHE, Bibliothèque SEM-LPTHE (Séminaire du LPTHE) cond-mat.stat-mech|hep-th|math-ph
Shouvik Datta ( ETH Zurich ) OPE coefficients from modularity
Abstract: Modular invariance in 2d CFTs relates low-energy data to high-energy asymptotics. In this talk, I shall demonstrate how modular properties of correlation functions on the torus and the sphere (mapped to a pillow geometry) can be used to extract high-energy asymptotics of OPE coefficients. The results are universal and have implications for 2-to-2 scattering of black holes and the eigenstate thermalization hypothesis.

Friday 22 June 2018, 14:30 at IPHT, Salle Claude Itzykson, Bât. 774 IPHT-SEM (Séminaire du IPHT) physics
Federico Becca ( SISSA, Trieste ) Spectral signatures of fractionalization in the frustrated Heisenberg model on the square lattice
Abstract: This seminar is organized in the framework of the PSI2 program "Topological phases of matter: from the quantum Hall effect to spin liquids" (Topmat) https://topmat.sciencesconf.org/

Monday 25 June 2018, 10:45 at LPTMC, Jussieu, room 3-17, 3rd floor, tower 23-22 SEM-LPTMC (Séminaire du Laboratoire de Physique Théorique de la Matière Condensée) cond-mat.mes-hall
Simon-Boris Moulieras-Mantisi ( Myndblue/Quatorze-IG ) Deux docteurs dans le monde de l'entreprise
Abstract: La formation universitaire reste méconnue de la majorité des acteurs du secteur privé et les liens entre ces deux mondes sont encore trop peu développés. Pourtant, la formation universitaire, et notamment au travers de la réalisation d'une thèse, offre de nombreux atouts que le docteur doit absolument apprendre à valoriser afin de s'ouvrir les portes du privé. Deux docteurs en physique, anciens du LPTMC, interviennent pour partager leur saut vers l'entreprise. Simon Moulieras, data scientist chez MyndBlue, à Polytechnique et Boris Mantisi, data scientist chez Quatorze IG, bureau d'études d'ingénierie basé dans le 13 ème arrondissement de Paris. Chacun parlera 20 minutes et il y aura ensuite du temps de discussion.

Monday 25 June 2018, 11:00 at IPHT, Salle Claude Itzykson, Bât. 774 IPHT-SEM (Séminaire du IPHT) physics
Allan Macdonald ( University of Texas, Austin ) Broken Symmetries near Topological Insulator/ Normal Insulator Phase Transitions
Abstract: This seminar is organized in the framework of the PSI2 program "Topological phases of matter: from the quantum Hall effect to spin liquids" (Topmat) https://topmat.sciencesconf.org/

Monday 25 June 2018, 11:00 at IPHT, Pièce 35, Bât. 774 IPHT-PHM (Séminaire de physique mathématique) math-ph
Jean-Emile Bourgine ( Séoul ) New Integrable Structures from N = 2 Super Yang-Mills Theories
Abstract: Perhaps the most insightful correspondence between integrable systems and supersymmetric quantum field theories follows from the work of Seiberg and Witten (1994) on N=2 Super Yang-Mills theories. Originally formulated for theories defined on a Euclidean space-time and classical systems, it was later observed (Nekrasov-Shatashvili 2009) that a certain deformation of the space-time induces a quantization of the corresponding integrable system. Furthermore, a second deformation parameter has been introduced, but its effect on the integrability side remained unclear. In this talk, I will describe three different approaches (geometric, perturbative, algebraic) to understand the role of this mysterious parameter.

Tuesday 26 June 2018, 11:00 at LPTMS, LPTMS, salle 201, 2ème étage, Bât 100, Campus d'Orsay LPTMS (Séminaire du Laboratoire de Physique Théorique et Modèles Statistiques (Orsay)) physics
Urna Basu ( LPTMS, Université Paris-Sud ) Active Brownian Motion in Two Dimensions
Abstract: We study the dynamics of a single active Brownian particle in a two-dimensional harmonic trap. The active particle has an intrinsic time scale set by the rotational diffusion. The harmonic trap also induces a relaxational time-scale. We show that the competition between these two time scales leads to a nontrivial time evolution for the active Brownian particle. At short times a strongly anisotropic motion emerges leading to anomalous persistence properties. At long-times, the stationary position distribution in the trap exhibits two different behaviours: a Gaussian peak at the origin in the strongly passive limit and a delocalised ring away from the origin in the opposite strongly active limit. The predicted stationary behaviours in these limits are in agreement with recent experimental observations. Réf: Urna Basu, Satya N. Majumdar, Alberto Rosso and Grégory Schehr, Active Brownian Motion in Two Dimensions, preprint cond-mat.stat-mech arXiv:1804.09027

Tuesday 26 June 2018, 11:30 at LPTENS, LPTENS library STR-LPT-ENS-HE (Séminaire commun LPTENS/LPTHE) hep-th
Julian Sonner ( Université de Genève ) TBA
Abstract: TBA

Tuesday 26 June 2018, 14:00 at APC, 483 A - Malevitch APC-TH (Seminar of the theory group of APC) hep-th
Yuichiro Tada ( Nagoya University ) Stochastic inflation in a general field space
Abstract: Inflationary models in non-trivial field spaces encoded by their non-canonical kinetic terms have attracted attentions recently. We have then extended the so-called stochastic formalism to such a general case. This formalism investigates the fluctuation of inflatons treating them as Brownian motions. This work highlights the involved problem of this formalism, related with the mathematical uncertainty of the definition of noise integral. Comparing the correlation functions in the stochastic formalism and quantum field theory, we clarify that this uncertainty cannot be removed but rather the smallness of this would be a new criterion of the validity for the application of this formalism. We also check that it does not affect the observable curvature perturbations so much at least in a single-field case. Practical application prescriptions of this formalism may be also mentioned.

Tuesday 26 June 2018, 16:00 at IPHT, Salle Claude Itzykson, Bât. 774 IPHT-HEP (Séminaire de physique des particules et de cosmologie) hep-ph
Davide Racco ( Université de Genève ) Cosmological signatures of the SM Higgs instability: Primordial Black Holes and Gravitational Waves
Abstract: For the current central values of the Higgs boson and top quark masses, the standard model Higgs potential develops an instability at a scale of the order of $10^{11}\,$GeV. We show that cosmological signatures of such instability could be dark matter in the form of primordial black holes and the production of gravitational waves, sourced by Higgs fluctuations during inflation. The existence of dark matter might not require physics beyond the standard model, and this hypothesis may find its confirmation through the detection of gravitational waves.

Tuesday 26 June 2018, 17:15 at DPT-PHYS-ENS, Jean Jaures (29 rue d'Ulm) SEM-PHYS-ENS (Colloquium du Département de Physique de l'ENS) physics.flu-dyn
William Young ( UC San Diego ) Long range propagation of ocean swell
Abstract: TBA

Wednesday 27 June 2018, 11:00 at IPHT, Amphi Claude Bloch, Bât. 774 IPHT-SEM (Séminaire du IPHT) physics
Alexander Wietek ( University of Innsbruck ) Numerical identification of quantum spin liquids
Abstract: The emergence of quantum spin liquid phases of matter from local spin interactions is of fundamental interest in contemporary condensed matter physics. While several exactly solvable toy models for quantum spin liquids have been proposed and investigated, the theoretical study of (frustrated) spin systems with more realistic interactions relies on numerical simulations. We give a short overview of numerical methods to identify topologically ordered states and focus on the method of using numerical exact diagonalization in combination with variational wave functions. We present recent advances of the method and show, how this approach has been applied to identify certain chiral spin liquids in two-dimensional frustrated Heisenberg models.   This seminar is organized in the framework of the PSI2 program "Topological phases of matter: from the quantum Hall effect to spin liquids" (Topmat) https://topmat.sciencesconf.org/

Thursday 28 June 2018, 11:00 at IPHT, Salle Claude Itzykson, Bât. 774 IPHT-SEM (Séminaire du IPHT) physics
Didier Poilblanc ( Université Paul Sabatier, Toulouse ) PEPS chiral spin liquids
Abstract: This seminar is organized in the framework of the PSI2 program "Topological phases of matter: from the quantum Hall effect to spin liquids" (Topmat) https://topmat.sciencesconf.org/

Thursday 28 June 2018, 15:30 at IPHT, Salle Claude Itzykson, Bât. 774 IPHT-SEM (Séminaire du IPHT) physics
Natalia Chepiga ( EPFL, Lausanne ) DMRG investigation of quantum dimer ladders
Abstract: This seminar is organized in the framework of the PSI2 program "Topological phases of matter: from the quantum Hall effect to spin liquids" (Topmat) https://topmat.sciencesconf.org/

Friday 29 June 2018, 10:00 at IPHT, Salle Claude Itzykson, Bât. 774
( https://courses.ipht.cnrs.fr/?q=fr/node/198 )
COURS (Cours) astro-ph|hep-ph
Marco Cirelli ( LPTHE Paris ) Dark matter phenomenology (3/5)
Abstract: Dark matter constitutes about 26\% of the present matter-energy content of the Universe (84\% of the matter-only content) and is one of the fundamental ingredients that shape the evolution of galaxies and the Universe. Surprisingly enough, the nature of dark matter is still unknown, and unveiling this mystery stands out as one of the most pressing issues in cosmology and particle physics. \par The course will present a basic overview of the state of the art in dark matter physics, mostly focussing on the phenomenology rather than on the many models proposed by particle theorists to explain it. \\ \par Plan of the lectures: \\ 1) Introduction, proofs of existence, and basic properties. Possible alternatives to particle dark matter and their status. \\ 2) Mechanisms of production in the early Universe: thermal freeze-out (in particular), freeze-in, asymmetric dark matter... \\ 3) Direct detection via nuclear recoils. \\ 4) Indirect detection with cosmic rays: charged particles, gamma rays (prompt and secondary), neutrinos. \\ 5) Collider searches (and possible complementarity of the searches).
Attachments:
  • 2017-2018.pdf (4503344 bytes) OPEN
  • 2018_Cirelli.pdf (4733534 bytes) OPEN

Friday 29 June 2018, 11:00 at LPTHE, Bibliothèque SEM-LPTHE (Séminaire du LPTHE) cond-mat.stat-mech|math-ph
Satya Majumdar ( LPTMS Orsay ) KPZ story
Abstract: The celebrated KPZ equation (Kardar, Parisi, Zhang, 1986) is an important milestone in statistical physics, originally introduced to describe the late time dynamics in two dimensional growth models. Over the last 30 years, the KPZ story has evolved in various interesting directions, making links on the way to different areas of physics and mathematics. This includes in particular the link to the famous Tracy-Widom distribution in random matrix theory. The story of KPZ is a very successful one, involving theoretical physics, mathematics and experiments--a fertile playground for interdisciplinary science. In this talk, I will review the evolution of the KPZ story, pointing out the important landmarks as I go along. At the very end, I will discuss some recent developments establishing a nice link between the KPZ height fluctuations and the edge physics in cold atom systems.

Friday 29 June 2018, 11:00 at IPHT, Amphi Claude Bloch, Bât. 774 IPHT-SEM (Séminaire du IPHT) physics
Julien Vidal ( LPTMC, Paris ) Phase transitions in string-nets
Abstract: This seminar is organized in the framework of the PSI2 program "Topological phases of matter: from the quantum Hall effect to spin liquids" (Topmat) https://topmat.sciencesconf.org/

Friday 29 June 2018, 14:30 at IPHT, Salle Claude Itzykson, Bât. 774 IPHT-SEM (Séminaire du IPHT) physics
Jean-Noël Fuchs ( LPTMC, Paris ) 16-fold way in the Kitaev honeycomb model
Abstract: This seminar is organized in the framework of the PSI2 program "Topological phases of matter: from the quantum Hall effect to spin liquids" (Topmat) https://topmat.sciencesconf.org/

Monday 2 July 2018, 10:45 at LPTMC, Jussieu, room 5-23, 5th floor, tower 13-12 SEM-LPTMC (Séminaire du Laboratoire de Physique Théorique de la Matière Condensée) cond-mat.mes-hall
Anthony Lesage ( LPTMC ) Antony Lesage (LPTMC)
Abstract: TBA

Monday 2 July 2018, 11:00 at IPHT, Amphi Claude Bloch, Bât. 774 IPHT-SEM (Séminaire du IPHT) physics
Haruki Watanabe ( Tokyo University ) Many-body Chern number and Thouless pump via twisted boundary condition
Abstract: This seminar is organized in the framework of the PSI2 program "Topological phases of matter: from the quantum Hall effect to spin liquids" (Topmat) https://topmat.sciencesconf.org/

Monday 2 July 2018, 14:30 at IPHT, Amphi Claude Bloch, Bât. 774 IPHT-SEM (Séminaire du IPHT) physics
Steve Simon ( Oxford University ) Topologically Ordered Matter and Why You Should be Interested
Abstract: In two dimensional topological phases of matter, processes depend on gross topology rather than detailed geometry. Thinking in 2 1 dimensions, particle world lines can be interpreted as knots or links, and the amplitude for certain processes becomes a topological invariant of that link. While sounding rather exotic, we believe that such phases of matter not only exist, but have actually been observed in quantum Hall experiments, and could provide a uniquely practical route to building a quantum computer. Possibilities have also been proposed for creating similar physics in systems ranging from superfluid helium to strontium ruthenate to semiconductor-superconductor junctions to quantum wires to spin systems to graphene to cold atoms. This seminar is organized in the framework of the PSI2 program "Topological phases of matter: from the quantum Hall effect to spin liquids" (Topmat) https://topmat.sciencesconf.org/

Tuesday 3 July 2018, 14:00 at APC, 483 A - Malevitch APC-TH (Seminar of the theory group of APC) hep-th
Léonie Canet ( Université de Grenoble ) Correlation functions in fully developed turbulence
Abstract: Turbulence is an ubiquitous phenomenon in natural and industrial fluid flows. Yet, it still lacks a satisfactory theoretical description. One of the main open issues is to calculate the statistical properties of the turbulent steady state, and in particular what is generically called intermittency effects, starting from the fundamental description of the fluid dynamics provided by Navier-Stokes equation. In this presentation, I will focus on isotropic and homogeneous turbulence in three-dimensional incompressible flows. In the first part, I will give an introduction on the basic phenomenology of turbulence, and show what are the typical manifestations of intermittency. In the second part, I will explain how one can derive exact asymptotic (i.e. at large wave- numbers) properties of the correlation functions in the turbulent state, using a field-theoretic approach, based on the Non-Perturbative Renormalisation Group, and compare them to numerical simulations and experiments.

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