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  IPHTSEM (Séminaire du IPHT)  physics 



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.Â I shall begin with a pedagogical introduction to the understanding of the essential phenomenology in terms of emergent particles called composite fermions. Â 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.Â 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 ( $ $ )  IPNTHEO (Séminaire du groupe de physique théorique de l'IPN Orsay)  nuclth 



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: 
Wednesday 20 June 2018, 15:30 at IPHT, Salle Claude Itzykson, Bât. 774  IPHTSEM (Séminaire du IPHT)  physics 



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  IPHTSEM (Séminaire du IPHT)  physics 



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  SEMLPTMUCP (Seminaires du LPTM , Universite de Cergy Pontoise)  mathph 



Abstract:  We discuss the notion of the quantum auxiliary linear problem and the associated problem of quantum DarbouxBäcklund 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 ZakharovShabat method are also discussed. 
Thursday 21 June 2018, 15:30 at IPHT, Salle Claude Itzykson, Bât. 774  IPHTSEM (Séminaire du IPHT)  physics 



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  LPTPTH (Particle Theory Seminar of LPT Orsay)  hepph 



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" nonthermal particle production in the context of dark matter freezein 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 coarsegrained quantities, such as particle occupation numbers, can be derived from a FokkerPlanck 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)  astrophhepph 



Abstract:  Dark matter constitutes about 26\% of the present matterenergy content of the Universe (84\% of the matteronly 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 freezeout (in particular), freezein, 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: 
Friday 22 June 2018, 10:30 at
IHES,
Centre de conférences Marilyn et James Simons ( Cours de l'IHES )  MATHIHES (TBA)  hepth 



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  SEMLPTHE (Séminaire du LPTHE)  condmat.statmechhepthmathph 



Abstract:  Modular invariance in 2d CFTs relates lowenergy data to highenergy 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 highenergy asymptotics of OPE coefficients. The results are universal and have implications for 2to2 scattering of black holes and the eigenstate thermalization hypothesis. 
Friday 22 June 2018, 14:30 at IPHT, Salle Claude Itzykson, Bât. 774  IPHTSEM (Séminaire du IPHT)  physics 



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 317, 3rd floor, tower 2322  SEMLPTMC (Séminaire du Laboratoire de Physique Théorique de la Matière Condensée)  condmat.meshall 



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  IPHTSEM (Séminaire du IPHT)  physics 



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  IPHTPHM (Séminaire de physique mathématique)  mathph 



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 YangMills theories. Originally formulated for theories defined on a Euclidean spacetime and classical systems, it was later observed (NekrasovShatashvili 2009) that a certain deformation of the spacetime 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 



Abstract:  We study the dynamics of a single active Brownian particle in a twodimensional harmonic trap. The active particle has an intrinsic time scale set by the rotational diffusion. The harmonic trap also induces a relaxational timescale. 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 longtimes, 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 condmat.statmech arXiv:1804.09027 
Tuesday 26 June 2018, 11:30 at LPTENS, LPTENS library  STRLPTENSHE (Séminaire commun LPTENS/LPTHE)  hepth 



Abstract:  TBA 
Tuesday 26 June 2018, 14:00 at APC, 483 A  Malevitch  APCTH (Seminar of the theory group of APC)  hepth 



Abstract:  Inflationary models in nontrivial field spaces encoded by their noncanonical kinetic terms have attracted attentions recently. We have then extended the socalled 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 singlefield case. Practical application prescriptions of this formalism may be also mentioned. 
Tuesday 26 June 2018, 16:00 at IPHT, Salle Claude Itzykson, Bât. 774  IPHTHEP (Séminaire de physique des particules et de cosmologie)  hepph 



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 DPTPHYSENS, Jean Jaures (29 rue d'Ulm)  SEMPHYSENS (Colloquium du Département de Physique de l'ENS)  physics.fludyn 



Abstract:  TBA 
Wednesday 27 June 2018, 11:00 at IPHT, Amphi Claude Bloch, Bât. 774  IPHTSEM (Séminaire du IPHT)  physics 



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 twodimensional frustrated Heisenberg models. Â 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  IPHTSEM (Séminaire du IPHT)  physics 



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  IPHTSEM (Séminaire du IPHT)  physics 



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)  astrophhepph 



Abstract:  Dark matter constitutes about 26\% of the present matterenergy content of the Universe (84\% of the matteronly 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 freezeout (in particular), freezein, 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: 
Friday 29 June 2018, 11:00 at LPTHE, Bibliothèque  SEMLPTHE (Séminaire du LPTHE)  condmat.statmechmathph 



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 TracyWidom distribution in random matrix theory. The story of KPZ is a very successful one, involving theoretical physics, mathematics and experimentsa 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  IPHTSEM (Séminaire du IPHT)  physics 



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  IPHTSEM (Séminaire du IPHT)  physics 



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 523, 5th floor, tower 1312  SEMLPTMC (Séminaire du Laboratoire de Physique Théorique de la Matière Condensée)  condmat.meshall 



Abstract:  TBA 
Monday 2 July 2018, 11:00 at IPHT, Amphi Claude Bloch, Bât. 774  IPHTSEM (Séminaire du IPHT)  physics 



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  IPHTSEM (Séminaire du IPHT)  physics 



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 semiconductorsuperconductor 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  APCTH (Seminar of the theory group of APC)  hepth 



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 NavierStokes equation. In this presentation, I will focus on isotropic and homogeneous turbulence in threedimensional 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 fieldtheoretic approach, based on the NonPerturbative Renormalisation Group, and compare them to numerical simulations and experiments. 
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