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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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Thursday 20 January 2022, 11:00 at IHP, zoom
( https://zoom.us/j/97507124810 Meeting ID: 975 0712 4810 Passcode: 1234 )
RENC-THEO (Rencontres Théoriciennes) hep-th
Michael Green A Novel Expression for an Integrated Correlator (in N = 4 supersymmetric Yang–Mills theory)
Abstract: This talk will present the exact expression for an integrated correlator of four superconformal primary operators in the stress tensor multiplet of SU(N) N = 4 supersymmetric Yang-Mills, based on the localised partition function of the N = 2∗ theory. I will show that this integrated correlator can be expressed as a strikingly simple two-dimensional lattice sum. This is a function of the complex Yang–Mills coupling, and is manifestly invariant under SL(2, Z) (Montonen–Olive) duality. The correlator satisfies a powerful Laplace equation that relates its value for SU(N) to its value for SU(N−1) and SU(N+1). For finite N the correlator reproduces and extends perturbative and non-perturbative N = 4 SYM results. The large-N expansion is holographically related to the SL(2, Z)-invariant low energy expansion of the type IIB superstring four-graviton amplitude in AdS5 × S5. The talk will also describe the extension of of these results to n-point correlators with n > 4 that violate the U(1) bonus symmetry maximally.

Thursday 20 January 2022, 14:00 at IHP, zoom
( https://zoom.us/j/97507124810 Meeting ID: 975 0712 4810 Passcode: 1234 )
RENC-THEO (Rencontres Théoriciennes) hep-th
Leonardo Rastelli Carving out the space of gravitational effective field theories
Abstract: I will review recent progress on carving out the space of consistent weakly coupled gravitational effective field theories, both in flat space and in Anti de Sitter space. The main technical tools are dispersive sum rules for the S-matrix (flat space) or for CFT correlators (AdS space), which follow from the general principles of unitarity and causality. Higher derivative couplings are expected to be of order one in the units of the UV cutoff. Our approach justifies this expectation and allows to prove rigorous bounds on the order one coefficients. In particular, we prove a precise version of the conjecture that any large N CFT with a large gap must be dual to a local effective field theory in AdS.

Monday 24 January 2022, 10:45 at LPTMC, online
( Zoom: https://us06web.zoom.us/j/81533150574?pwd=NlM1ZlJvUTQvZUxpVmV6QWdMbmlLQT09 Meeting ID: 815 3315 0574 Passcode: 336254 )
SEM-LPTMC (Séminaire du Laboratoire de Physique Théorique de la Matière Condensée) cond-mat
Hadrien Vroylandt ( Institut des Sciences du Calcul et des Données, Sorbonne Université ) Learning the dynamics of systems with memory: Generalized Langevin equations
Abstract: Generalized Langevin equations with non-linear forces and memory kernels are commonly used to describe the effective dynamics of coarse-grained variables in molecular dynamics. Such reduced dynamics play an essential role in the study of a broad class of processes, ranging from chemical reactions in solution to conformational changes in biomolecules or phase transitions in condensed matter systems. I will first discuss the derivation of the generalized Langevin equations, emphasizing the need for memory in the effective dynamics due to the lack of a proper separation of time scales. Then, I will turn on the inference of such generalized Langevin equations from observed trajectories, using a maximum likelihood approach. This data-driven approach provides a reduced dynamical model for collective variables, enabling the accurate sampling of their long-time dynamical properties at a computational cost drastically reduced with respect to all-atom numerical simulations. I will illustrate the potential of this method on several model systems, both in and out of equilibrium.

Monday 24 January 2022, 14:00 at IPHT, Salle Claude Itzykson, Bât. 774 IPHT-STA (Séminaire de Physique Statistique, CEA/Saclay) cond-mat
Emilio Trevisani ( IPhT ) TBA

Tuesday 25 January 2022, 11:00 at LPTMS, Petit amphi, bâtiment Pascal n° 530+ zoom
( For zoom info, please write to valentina.ros@universite-paris-saclay.fr or check the LPTMS website )
LPTMS (Séminaire du Laboratoire de Physique Théorique et Modèles Statistiques (Orsay)) cond-mat.stat-mech
Jacqueline Bloch ( C2N ) Using cavity polariton lattices as analog simulators
Abstract: An analog simulator is a synthetic physical system, which emulates in a controlled way a physical problem. You can get answers about the physical problem by directly performing experiments on the simulator. This approach is particularly relevant for quantum problems where computation times grows exponentially with the system’s size. In the present seminar, I will present the polariton platform and explain how it is relevant for analog simulation of many interesting open problems.  Cavity polaritons are hybrid exciton-photon quasi-particle emerging from the strong coupling regime between photons confined in an optical cavity and excitons confined in quantum wells. They present physical properties reflecting their mixed nature. From the photon part, they inherit a small effective mass and can be confined in lattices with typical dimensions of the order of a few microns. Their excitonic part endows them with inter-particle interactions resulting  in a giant Kerr non linearity. Moreover the system is intrinsically open and out of equilibrium because photons constantly leak out from the cavity. Cavity polaritons have been shown to present fascinating properties such as Bose Einstein condensation at elevated temperature, superfluidity, multistability etc [1]. In the present talk, I will explain how the polariton plateform is particularly suitable to realize analog simulation of open complex systems and explore fundamental physical phenomena. I will describe a few recent results of our group:  How do wave localize in exotic quasi-crystals and how fractality does develop? This physics can be emulated with polariton lattices [2] Polariton condensates are out of equilibrium and their phase dynamics has been predicted to obey the celebrated Kardar Parisi Zhang (KPZ) equation. We have been able to reveal experimentally universal KPZ scaling laws in the first order coherence of a 1D polariton condensate.[3] Polariton lattices are also very interesting for the investigation of topological photonics. In particular, the ability to drive the system with controlled phases opens a new paradigm for non-linear topological photonics. [4]  References : [1]  Ciuti & I. Carusotto, Quantum fluids of light, Rev. Mod. Phys. 85, 299 (2013) [2] V. Goblot et al. Emergence of criticality through a cascade of delocalization transitions in quasiperiodic chains, Nature Physics 16, 832 (2020) [3] Q. Fontaine et al., Observation of KPZ universal scaling in a one-dimensional polariton condensate, arXiv:2112.09550 (2021) [4] N. Pernet et al., N. Pernet, et al., Topological gap solitons in a 1D non-Hermitian lattice, arXiv:2101.01038 (to appear 2022)

Tuesday 25 January 2022, 13:45 at IHES, Amphithéâtre Léon Motchane
( Séminaire Laurent Schwartz -- EDP et applications )
MATH-IHES (TBA) math
Pierre Raphaël ( Université de Cambridge ) Explosion sur critique : brisure d’échelle et scénario de type front

Tuesday 25 January 2022, 14:00 at APC, contact roperpol@apc.in2p3.fr for Zoom meeting details APC-TH (Seminar of the theory group of APC) gr-qc
Marc Casals ( University College Dublin ) Black Hole Stability Properties: from Instability of Extremal Kerr to Violation of Cosmic Censorship
Abstract: Black holes in the Universe do not exist in isolation but, rather, they are surrounded by matter. It is therefore important to study the stability properties of black holes under matter field perturbations. In this talk we will discuss the stability properties under classical field perturbations of several rotating (Kerr) black hole spacetimes. In particular, we will present recent results on some of the mode stability properties of the following: (i) a maximally-rotating (extremal) Kerr black hole, whose event horizon suffers from the so-called Aretakis instability; (ii) Kerr-de Sitter spacetime, representing a Kerr black hole in a Universe with accelerated expansion, and so possessing a cosmological horizon as well as an event horizon; and (iii) the inner (Cauchy) horizon of Kerr- Newman-de Sitter spacetime, representing a charged Kerr-de Sitter black hole, where we find evidence for violation of Penrose’s strong Cosmic Censorship conjecture.

Tuesday 25 January 2022, 14:00 at LPTHE, Library & Zoom link in comments
( Join Zoom Meeting https://cern.zoom.us/j/67310205088?pwd=cytWVUJTZTZMWjlER3JwcXF2SkxLdz09 Meeting ID: 673 1020 5088 Passcode: 127835 )
LPTHE-PPH (Particle Physics at LPTHE) hep-ph
Redamy Perez-Ramos ( LPTHE ) Hadron correlations on the search of new physics beyond the standard model in the e+e- annihilation and the LHC
Abstract: The analysis of azimuthal correlations along with jet shapes in multiparticle production can be useful to uncover the existence of new physics beyond the Standard Model, e.g., Hidden Valley, in the e + e − annihilation at high energies. In this seminar, based on previous theoretical studies and using PYTHIA8 event generator, it is found that both azimuthal and rapidity long-range correlations are enhanced due to the presence of a new stage of matter on top of the QCD partonic cascade. Ridge structures, similar to those observed at the LHC, show up providing a possible signature of new physics at future e + e −colliders. Preliminary results on pp collisions will be discussed for completeness.

Tuesday 25 January 2022, 15:00 at IHES, Amphithéâtre Léon Motchane
( Séminaire Laurent Schwartz -- EDP et applications )
MATH-IHES (TBA) math
Laurent Desvillettes ( Institut Universitaire de France et Université de Paris ) Dissipation d'entropie pour les opérateurs de collision

Thursday 27 January 2022, 14:00 at LPTHE, Amphi Charpak LPNHE groundfloor between towers 23 and 32 and online (zoom) TQM (Theory of quantum matter) math-ph
Félix Werner ( LKB Paris ) TBA
Abstract: https://us06web.zoom.us/j/84343644046?pwd=aEFRNG96ZlZYSTJSWUtUQ0t4aHRPdz09

Thursday 27 January 2022, 14:00 at LPENS, E227a LPTENS-HE (Séminaire commun LPTENS-LPTHE) hep-th
Eric Perlmutter ( IPhT ) TBA

Monday 31 January 2022, 13:30 at LPENS, L378 LPENS-MDQ (Séminaire Matériaux et Dispositifs Quantiques du LPENS) cond-mat
François Dubin ( Institut des Nansciences de Paris, INSP ) TBA

Tuesday 1 February 2022, 11:00 at LPTMS, Salle des séminaires du FAST et du LPTMS, bâtiment Pascal n°530 + zoom
( For zoom info, please write to valentina.ros@universite-paris-saclay.fr or check LPTMS website. )
LPTMS (Séminaire du Laboratoire de Physique Théorique et Modèles Statistiques (Orsay)) cond-mat.stat-mech
Guilhem Semerjian ( LPENS ) The planted matching problem
Abstract: This talk will present some results, obtained with statistical mechanics techniques, on the planted matching problem. The latter is an inference problem, where the goal is to recover a perfect matching hidden (planted)  in a weighted graph, the weights on the planted and non-planted edges being drawn with two different distributions. Joint work with Gabriele Sicuro and Lenka Zdeborova.

Tuesday 1 February 2022, 14:00 at APC, contact roperpol@apc.in2p3.fr for Zoom meeting details APC-TH (Seminar of the theory group of APC) gr-qc
Matt Lewandowski ( Northwestern University ) Baryonic effects in the Effective Field Theory of Large-Scale Structure and an analytic recipe for lensing in CMB-S4
Abstract: Upcoming Large-Scale Structure surveys will likely become the next leading sources of cosmological information, making it crucial to have a precise understanding of the influence of baryons on cosmological observables. The Effective Field Theory of Large-Scale Structure (EFTofLSS) provides a consistent way to predict the clustering of dark matter and baryons on large scales, where their leading corrections in perturbation theory are given by a simple and calculable functional form even after the onset of baryonic processes. In this paper, we extend the two- fluid-like system up to two-loop order in perturbation theory. Along the way, we show that a new linear counterterm proportional to the relative velocity of the fluids could generically be present, but we show that its effects are expected to be small in our universe. Regardless, we show how to consistently perform perturbation theory in the presence of this new term. We find that the EFTofLSS at two-loop order can accurately account for the details of baryonic processes on large scales. We compare our results to a hydrodynamical N-body simulation at many redshifts and find that the counterterms associated with the leading corrections to dark matter and baryons start to differ between redshifts z ≈ 3 and z ≈ 2, signaling the onset of star-formation physics. We then use these fits to compute the lensing power spectrum, show that the understanding of baryonic processes will be important for analyzing CMB-S4 data, and show that the two-loop EFTofLSS accurately captures these effects for ℓ ≲ 2000. Our results are also potentially of interest for current and future weak lensing surveys.

Friday 4 February 2022, 13:00 at LPENS, Salle Favard, IBENS BIOPHY-ENS-ESPCI (Séminaire de biophysique ENS-ESPCI) physics.bio-ph
Herve Turlier ( College de France ) TBA
Abstract: TBA

Tuesday 8 February 2022, 11:00 at LPTMS, Salle des séminaires du FAST et du LPTMS, bâtiment Pascal n°530+zoom
( For zoom info, please write to valentina.ros@universite-paris-saclay.fr )
LPTMS (Séminaire du Laboratoire de Physique Théorique et Modèles Statistiques (Orsay)) cond-mat.stat-mech
Aurelien Grabsch ( LPTMC ) TBA

Tuesday 8 February 2022, 14:00 at APC, seminar room 483A, contact roperpol@apc.in2p3.fr for Zoom meeting details APC-TH (Seminar of the theory group of APC) gr-qc
Gills Cohen-Tannoudji ( CEA ) Cold dark matter: A gluonic Bose-Einstein condensate in Anti-de Sitter space time

Tuesday 8 February 2022, 17:15 at DPT-PHYS-ENS, Amphi Jaurès - Ecole normale supérieure 29 rue d'Ulm 75005 PARIS COLLOQUIUM-ENS (Colloquium of the Physics Department of ENS) physics
Matteo Barsuglia ( APC - CNRS ) Ground based gravitational-wave astronomy in the next decades
Abstract: After the first gravitational wave detection in 2015 and the GW170817 multi-messenger observation, the gravitational-wave astronomy has evolved rapidly. LIGO and Virgo detectors have performed their 3rd observing run between April 2019 and March 2020 and the third catalog of gravitational-waves sources (GWTC-3) has just been released, with a total of 90 sources detected so far. Upgrades of LIGO and Virgo are planned in the decade 2020-2030, increasing the scientific potential of the gravitational-wave detector network, which will include two more instruments in the next years: KAGRA in Japan and a third LIGO in India. In the decade 2030, the Einstein Telescope project, an European underground gravitational-wave observatory, aims to increase the sensitivity of current detector by one order of magnitude. In this seminar, after an summary about the current gravitational-wave observations, I will be describe in detail the LIGO-Virgo plans for the 2020 decade and then the scientific objectives and plans for Einstein Telescope. Matteo Barsuglia, directeur de recherche au CNRS (au laboratoire Astroparticule et Cosmologie), responsable pour la France de Virgo et Einstein Telescope.

Thursday 10 February 2022, 11:00 at CPHT, Zoom https://ecolepolytechnique.zoom.us/j/81221828492 SEM-CPHT (Séminaire du CPHT) hep-th
Niko Jokela ( University of Helsinki ) TBA
Abstract: TBA

Thursday 10 February 2022, 14:00 at LPTHE, INSP Jussieu towers 22-23 room 3-17 and online (zoom) TQM (Theory of quantum matter) math-ph
Rebeca Ribeiro ( C2N Palaiseau ) TBA
Abstract: https://us06web.zoom.us/j/88244544737?pwd=N2dnVllwSGxKRHRRVjZFb0taNFk3QT09

Friday 11 February 2022, 13:00 at LPENS, Salle Favard, IBENS BIOPHY-ENS-ESPCI (Séminaire de biophysique ENS-ESPCI) physics.bio-ph
Feng-Ching Tsai ( Institut Curie ) TBA
Abstract: TBA

Monday 14 February 2022, 13:30 at LPENS, L361 LPENS-MDQ (Séminaire Matériaux et Dispositifs Quantiques du LPENS) cond-mat
Jean-Damien Pillet ( Ecole Polytechnique ) TBA

Tuesday 15 February 2022, 11:00 at LPTMS, Salle des séminaires du FAST et du LPTMS, bâtiment Pascal n°530+zoom
( For zoom info, please write to valentina.ros@universite-paris-saclay.fr )
LPTMS (Séminaire du Laboratoire de Physique Théorique et Modèles Statistiques (Orsay)) cond-mat.stat-mech
Adam Nahum ( LPENS ) TBA

Tuesday 15 February 2022, 14:00 at APC, contact roperpol@apc.in2p3.fr for Zoom meeting details APC-TH (Seminar of the theory group of APC) gr-qc
Lucas Pinol ( IFT ) TBA

Friday 18 February 2022, 13:00 at LPENS, Zoom BIOPHY-ENS-ESPCI (Séminaire de biophysique ENS-ESPCI) physics.bio-ph
Andrea Cavagna ( Instituto dei Sistemi Complessi, Rome ) TBA
Abstract: TBA

Thursday 24 February 2022, 14:00 at LPTM, Distanciel TEAMS SEM-LPTM-UCP (Seminaires du LPTM , Universite de Cergy Pontoise) cond-mat.stat-mech
Aurélien Grabsch ( LPTMC Sorbonne Université, Paris ) Generalised Density Profiles in Single-File Systems
Abstract: Single-file transport, where particles diffuse in narrow channels while > not overtaking each other, is a fundamental model for the tracer > subdiffusion observed in confined systems, such as zeolites or carbon > nanotubes. This anomalous behavior originates from strong bath-tracer > correlations in 1D, which we characterise in this talk through > Generalised Density Profiles (GDPs). These GDPs have however remained > elusive, because they involve an infinite hierarchy of equations. Here, > for the Symmetric Exclusion Process, a paradigmatic model of single-file > diffusion, we break the hierarchy and unveil a closed equation satisfied > by these correlations, which we solve. Beyond quantifying the > correlations, the central role of this equation as a novel tool for > interacting particle systems will be further demonstrated by showing > that it applies to out-of equilibrium situations, other observables and > other representative single-file systems. >

Tuesday 1 March 2022, 17:15 at DPT-PHYS-ENS, Amphi Jaurès - Ecole normale supérieure 29 rue d'Ulm 75005 PARIS COLLOQUIUM-ENS (Colloquium of the Physics Department of ENS) physics
Hakim Atek TBA
Abstract: TBA

Monday 7 March 2022, 13:30 at LPENS, L378 LPENS-MDQ (Séminaire Matériaux et Dispositifs Quantiques du LPENS) cond-mat
Gerbold Ménard ( Laboratoire de Physique et d'Etude des Matériaux, LPEM ) TBA

Tuesday 8 March 2022, 11:00 at LPTMS, Salle des séminaires du FAST et du LPTMS, bâtiment Pascal n°530 + zoom
( For zoom info, please write to valentina.ros@universite-paris-saclay.fr )
LPTMS (Séminaire du Laboratoire de Physique Théorique et Modèles Statistiques (Orsay)) cond-mat.stat-mech
Lorenzo Piroli ( LPENS ) TBA

Thursday 10 March 2022, 14:00 at LPTHE, INSP Jussieu towers 22-23 room 3-17 and online (zoom) TQM (Theory of quantum matter) math-ph
Benoît Douçot ( LPTHE ) TBA
Abstract: https://us06web.zoom.us/j/81226484885?pwd=K1ZRMWlrR1Y0UEIxcnJpclJHa1lUZz09 ID de réunion : 812 2648 4885 Code secret : 066997

seminars from series at institute
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