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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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Monday 27 March 2017, 11:00 at IPHT, Salle Claude Itzykson, Bât. 774 IPHT-PHM (Séminaire de physique mathématique) math-ph
Vincent Rivasseau ( LPT Orsay ) Loop Vertex Representation
Abstract: We shall discuss an integral representation that could be useful to prove easily Borel summability of matrix models with arbitrary order interactions.

Tuesday 28 March 2017, 10:30 at IHES, Amphithéâtre Léon Motchane
( Cours des professeurs permanents de l'IHES )
MATH-IHES (TBA) hep-th
Hugo Duminil-Copin ( IHES ) Sharp threshold phenomena in Statistical Physics (2/4)
Abstract: In this course, we will present different techniques developed over the past few years, enabling mathematicians to prove that phase transitions are sharp. We will focus on a few classical models of statistical physics, including Bernoulli percolation, the Ising model and the random-cluster model.

Tuesday 28 March 2017, 11:00 at IPHT, Salle Claude Itzykson, Bât. 774 SEM-EXCEP (Séminaire exceptionel) physics
Jean-Yves Ollitrault ( IPhT ) Des quarks et des gluons
Abstract: Au coeur de la matière se trouvent les atomes, au coeur d'un atome se trouve un minuscule noyau, et le noyau de l'atome lui-même est constitué de particules qu'on dit "élémentaires" car on les pense indivisibles, les quarks et les gluons. On montrera comment un accélérateur de 27 kilomètres de long permet d'examiner sous toutes les coutures ces particules, et ce qu'apporte la recherche théorique sur ce sujet.

Tuesday 28 March 2017, 14:00 at LPTM, 4.13 St Martin II SOUTEN-TH (Soutenance de thèse) cond-mat
Valentin Bois ( LPTM UCP Cergy Pontoise ) Effet de la deuxieme orbitale dans les systemes 1d de fermions alcalino terreux ultrafroids
Abstract: TBA

Tuesday 28 March 2017, 14:00 at APC, 371 A - Klein (salle inhabituelle) APC-TH (Seminar of the theory group of APC) hep-th
Nicola Tamanini ( APC ) Late time cosmology with LISA: probing the cosmic expansion with massive black hole binary mergers as standard sirens
Abstract: I will summarize the potential of the LISA mission to constrain the expansion history of the universe using massive black hole binary mergers as gravitational wave standard sirens. After briefly reviewing the concept of standard siren, I will outline the analysis and methodologies to use LISA as a cosmological probe, and present estimates for the power of LISA in constraining cosmological parameters for both standard and alternative cosmological models.

Tuesday 28 March 2017, 14:00 at LPTHE, library LPTHE-PPH (Particle Physics at LPTHE) hep-ph
Lukas Witkowski ( APC Paris ) A biography of the Weak Gravity Conjecture
Abstract: In its original form the Weak Gravity Conjecture (WGC) is a proposed constraint on gauge theories coupled to gravity. From this simple starting point one can however arrive at far reaching implications: if true, the WGC gives rise to severe constraints on models of large-field inflation and it may have important consequences for the stability of the string theory landscape. It is this connection to inflation, which has led to renewed interest in the WGC in the recent years. However, the progress made in this time comes with a price: there exist several competing formulations of the conjecture. Further, there are various generalisations with varying levels of support. While more evidence has been gathered, there is still no proof. In this talk I want to give a status report on the WGC: in particular, I will present the current formulations, recent evidence and the status quo on applications to cosmology and particle physics.

Tuesday 28 March 2017, 15:30 at LPTHE, bibliothèque STR-LPT-ENS-HE (Séminaire commun LPTENS/LPTHE) hep-th
Vincent Rivasseau ( LPT Orsay ) The Emergent Melonic Spell
Abstract: The Gurau-Witten (GW) tensor models provide a field theoretic reformulation of the Sachdev-Ye-Kitaev model (SYK), with the same fascinating properties. But GW models have in addition a rich random-geometric content which will be discussed.

Wednesday 29 March 2017, 11:00 at LPTENS, Conference room 4 SEM-LPTENS (Seminaire du LPTENS) hep-th
Albrecht Klemm ( Bonn University ) Effective action from M-theory on twisted connected sum $G_2$-manifolds
Abstract: We study the four-dimensional low energy effective N=1 supergravity theory of the dimensional reduction of M-theory on $G_2$-manifolds, which are constructed by Kovalev's twisted connected sum gluing suitable pairs of asymptotically cylindrical Calabi--Yau threefolds $X_{L/R}$ augmented with a circle $S^1$. In the Kovalev limit the Ricci-flat $G_2$-metrics are approximated by the Ricci-flat metrics on $X_{L/R}$ and we identify the universal modulus --- the Kovalon --- that parametrizes this limit. We observe that the low energy effective theory exhibits in this limit gauge theory sectors with extended supersymmetry. We determine the universal (semi-classical) K\"ahler potential of the effective N=1 supergravity action as a function of the Kovalon and the volume modulus of the $G_2$-manifold. This K\"ahler potential fulfills the no-scale inequality such that no anti-de-Sitter vacua are admitted. We describe geometric degenerations in $X_{L/R}$, which lead to non-Abelian gauge symmetries enhancements with various matter content. Studying the resulting gauge theory branches, we argue that they lead to transitions compatible with the gluing construction and provide many new explicit examples of $G_2$-manifolds. (based on 1702.05435 )

Wednesday 29 March 2017, 14:15 at IPHT, Salle Claude Itzykson, Bât. 774 IPHT-MAT (Séminaire de matrices, cordes et géométries aléatoires) hep-th
Andreas Braun ( Oxford ) Polytopes and G2 Mirror Symmetry
Abstract: Millions of novel examples of compact G2 holonomy manifolds have been given in recent years as twisted connected sums of asymptotically cylindrical Calabi-Yau threefolds. For compactifications of type II string theories on such G2 manifolds, we give a construction of their mirrors. Similar to Batyrev's construction of Calabi-Yau mirrors, pairs of polytopes play a crucial role.

Thursday 30 March 2017, 11:00 at LPTHE, Bibliothèque SEM-INFOR (Séminaire informel) cond-mat.stat-mech
Mattia Cafasso ( Université d'Angers ) Le modèle de Kontsevich: phénomènes de Stokes et universalité.
Abstract: Pendant mon séminaire j'expliquerai comment on peut décrire, de façon analytique, la convergence du modèle de Kontsevich vers certaines solutions de la hiérarchie de la première équation de Painlevé, et quelle est leur monodromie. Mon outil principale sera la théorie des transformations de Darboux. Ensuite, je discuterai l'universalité (dans le sens de la théorie de matrices aléatoires) de ce modèle.

Thursday 30 March 2017, 11:00 at IHES, Amphithéâtre Léon Motchane MATH-IHES (TBA) hep-th
Raymond E. Goldstein ( University of Cambridge & IHES ) Upside Down and Inside Out: The Biomechanics of Cell Sheet Folding
Abstract: Deformations of cell sheets are ubiquitous in early animal development, often arising from a complex and poorly understood interplay of cell shape changes, division, and migration. In this talk I will describe an approach to understanding such problems based on perhaps the simplest example of cell sheet folding: the “inversion” process of the algal genus Volvox, during which spherical embryos literally turn themselves inside out through a process hypothesized to arise from cell shape changes alone. Through a combination of light sheet microscopy and elasticity theory a quantitative understanding of this process is now emerging.

Thursday 30 March 2017, 13:30 at DPT-PHYS-ENS, room Conf. IV, 24 Rue Lhomond, ENS Paris SEM-PHYS-ENS (Colloquium du Département de Physique de l'ENS) cond-mat
Immanuel Bloch ( Max Planck Institute for Quantum Optics, Munich ) TBA
Abstract: TBA

Thursday 30 March 2017, 16:00 at LPT, salle 114, 1er etage, batiment 210 SEM-LPT (Séminaire de Physique des Particules du LPT) hep-ph
Aritra Gupta ( Harish-Chandra Research Institute, Allahabad ) TBA

Thursday 30 March 2017, 16:30 at INSP, 22-23 salle 317 au 3ème étage SEM-INSP (Séminaire général de l'INSP) physics|physics.atom-ph|physics.gen-ph
Aldo Antognini ( ETH Zurich ) The proton radius puzzle
Abstract: We have measured several 2S-2P transitions in muonic hydrogen ($\mu$p), muonic deuterium ($\mu$d) and muonic helium ions ($\mu^3$He, $\mu^4$He). From muonic hydrogen we extracted a proton charge radius 20 times more precise than obtained from electron-proton scattering and hydrogen high-precision laser spectroscopy but at a variance of 7$\sigma$; from these values. This discrepancy is nowadays referred to as the "proton radius puzzle". New insight has been recently provided by the first determination of the deuteron charge radius from laser spectroscopy of $\mu$d. The status of the proton charge radius puzzle including the new insights obtained by $\mu$d spectroscopy will be discussed.

Friday 31 March 2017, 10:00 at IPHT, Salle Claude Itzykson, Bât. 774
( https://courses.ipht.cnrs.fr/?q=fr/node/166 )
COURS (Cours) astro-ph|hep-th
John Joseph Carrasco ( IPhT ) Graphical insights, with applications from QCD to cosmology (6/6)
Abstract: Graphs, at their most abstract, provide a language for describing relationships, one which has long been beneficial for the program of physical prediction. Combined with the Wilsonian understanding of effective field theory, perturbative analysis finds a role in predictions relevant to all scales, from processes describing the scattering of primordial gravitons, to QCD interactions at CERN's Large Hadron Collider, to establishing the astrophysical in-spiral and consequent post-merger ringing out of black holes, to the evolution of the largest scales cosmologically conceivable. Modern advances in scattering amplitude calculation have reemphasized the role of graphical organization towards efficient prediction, generalizing away from brute Feynman calculation, but yielding structural insights suggestive of a new type of unification touching predictions relevant to all of these scales. \par In these lectures I will talk about graphical organization of perturbative prediction, emphasizing scattering amplitudes, but with an eye towards generalization. \\ - GENERALIZED UNITARITY METHODS. How verification can be inverted towards construction. 1 lecture. \\ - COLOR-KINEMATICS (``BCJ'') DUALITY AND ASSOCIATED DOUBLE-COPY. Exploring both computational advantages as well as unifying structure exposed. Relevant theories include: Chiral Pions, Yang-Mills, QCD, Born-Infeld, Volkov-Akulov, Galileons, Einstein-Hilbert Gravity, Open and Closed string theories. 2 lectures. \\ - QCD. Generalizations particularly relevant to QCD calculations (massive, non-adjoint representations). 1 lecture. \\ - GRAVITY/COSMOLOGY. Application of some of these ideas to astrophysical and cosmological classical solutions in gravity. 2 lectures.
Attachments:
  • 2016-2017.pdf (5422338 bytes) OPEN
  • 2017_Carrasco.pdf (4705214 bytes) OPEN

Tuesday 4 April 2017, 10:30 at IHES, Amphithéâtre Léon Motchane
( Cours des professeurs permanents de l'IHES )
MATH-IHES (TBA) hep-th
Hugo Duminil-Copin ( IHES ) Sharp threshold phenomena in Statistical Physics (3/4)
Abstract: In this course, we will present different techniques developed over the past few years, enabling mathematicians to prove that phase transitions are sharp. We will focus on a few classical models of statistical physics, including Bernoulli percolation, the Ising model and the random-cluster model.

Tuesday 4 April 2017, 14:00 at APC, 483 A - Malevitch APC-TH (Seminar of the theory group of APC) hep-th
Zhang Yongchao ( Université Libre de Bruxelles ) Long lived light scalar in the minimal left-right symmetric model
Abstract: In the minimal left-right symmetric model which could accommodate the tiny neutrino masses via TeV seesaw mechanism, the neutral scalar from the right-handed symmetry breaking sector could be much lighter than the electroweak scale. We discuss the constraints on this particle from low-energy flavor observables, e.g. meson oscillations and rare decays, and find that such a light particle is necessarily long-lived, and can be searched for at the LHC via displaced signals of a collimated photon jet, if its mass is of order GeV scale. This decay mode provides a new test of TeV scale left-right model.

Wednesday 5 April 2017, 14:15 at IPHT, Salle Claude Itzykson, Bât. 774 IPHT-MAT (Séminaire de matrices, cordes et géométries aléatoires) hep-th
Robin Terrisse ( IPNL Lyon ) TBA

Thursday 6 April 2017, 11:00 at IHES, Amphithéâtre Léon Motchane MATH-IHES (TBA) hep-th
Raymond E. Goldstein ( University of Cambridge & IHES ) Cytoplasmic Streaming and Collective Behavior in Microswimmer Suspensions
Abstract: The field of "active matter" focuses on the collective behaviour of large numbers of individual units (molecular motors, cells, organisms) which inject energy into a fluid at the small scales, creating large-scale nonequilibrium patterns. In this talk I will link together two historically important examples of active matter - concentrated suspensions of bacteria and cytoplasmic streaming in plant and animal cells - to illustrate recent experimental and theoretical developments in the area of self-organization.

Thursday 6 April 2017, 14:00 at LPT, cosmology room 110, bldg 210, 1st floor SEM-LPT (Séminaire de Physique des Particules du LPT) hep-ph
Sebastian Garcia-Saenz ( IAP ) Galileon p-form theories
Abstract: The space based interferometer LISA has a great potential in probing cosmology. This talk presents two observables through which LISA could provide us with new information on the characteristics of the universe, complementary to what can be gathered from electromagnetic observations : the detection of a stochastic background of gravitational waves coming from the very early universe, and the use of massive black hole binaries as standard sirens to test the expansion of the universe.

Tuesday 11 April 2017, 10:30 at IHES, Amphithéâtre Léon Motchane
( Cours des professeurs permanents de l'IHES )
MATH-IHES (TBA) hep-th
Hugo Duminil-Copin ( IHES ) Sharp threshold phenomena in Statistical Physics (4/4)
Abstract: In this course, we will present different techniques developed over the past few years, enabling mathematicians to prove that phase transitions are sharp. We will focus on a few classical models of statistical physics, including Bernoulli percolation, the Ising model and the random-cluster model.

Tuesday 11 April 2017, 10:30 at IHES, Centre de conférences Marilyn et James Simons
( Séminaire de Géométrie Arithmétique Paris-Pékin-Tokyo )
MATH-IHES (TBA) hep-th
Peter Scholze ( Université de Bonn et IHES ) The geometric Satake equivalence in mixed characteristic
Abstract: In order to apply V. Lafforgue's ideas to the study of representations of p-adic groups, one needs a version of the geometric Satake equivalence in that setting. For the affine Grassmannian defined using the Witt vectors, this has been proven by Zhu. However, one actually needs a version for the affine Grassmannian defined using Fontaine's ring B_dR, and related results on the Beilinson-Drinfeld Grassmannian over a self-product of Spa({\mathbb Q}_p). These objects exist as diamonds, and in particular one can make sense of the fusion product in this situation; this is a priori surprising, as it entails colliding two distinct points of Spec({\mathbb Z}). The focus of the talk will be on the geometry of the fusion product, and an analogue of the technically crucial ULA (Universally Locally Acyclic) condition that works in this non-algebraic setting.

Tuesday 11 April 2017, 10:30 at IHES, Centre de conférences Marilyn et James Simons
( Séminaire de Géométrie Arithmétique Paris-Pékin-Tokyo )
MATH-IHES (TBA) hep-th
Peter Scholze ( Université de Bonn et IHES ) The geometric Satake equivalence in mixed characteristic
Abstract: In order to apply V. Lafforgue's ideas to the study of representations of p-adic groups, one needs a version of the geometric Satake equivalence in that setting. For the affine Grassmannian defined using the Witt vectors, this has been proven by Zhu. However, one actually needs a version for the affine Grassmannian defined using Fontaine's ring B_dR, and related results on the Beilinson-Drinfeld Grassmannian over a self-product of Spa({\mathbb Q}_p). These objects exist as diamonds, and in particular one can make sense of the fusion product in this situation; this is a priori surprising, as it entails colliding two distinct points of Spec({\mathbb Z}). The focus of the talk will be on the geometry of the fusion product, and an analogue of the technically crucial ULA (Universally Locally Acyclic) condition that works in this non-algebraic setting.

Tuesday 11 April 2017, 11:00 at LPTENS, LPTENS Library STR-LPT-ENS-HE (Séminaire commun LPTENS/LPTHE) hep-th
Christoph Keller ( ETH Zurich ) TBA
Abstract: TBA

Tuesday 11 April 2017, 14:00 at APC, 483 A - Malevitch APC-TH (Seminar of the theory group of APC) hep-th
Giulia Cusin ( Université de Genève ) TBA

Wednesday 12 April 2017, 14:15 at IPHT, Salle Claude Itzykson, Bât. 774 IPHT-MAT (Séminaire de matrices, cordes et géométries aléatoires) hep-th
Savdeep Sethi ( University of Chicago ) (TBA)

Thursday 13 April 2017, 11:00 at IHES, Amphithéâtre Léon Motchane MATH-IHES (TBA) hep-th
Raymond E. Goldstein ( University of Cambridge & IHES ) Leonardo, Rapunzel, and the Mathematics of Hair
Abstract: From Leonardo da Vinci to the Brothers Grimm our fascination with hair has endured in art and science. We love it for its “body” or “volume”, the fluffiness and elasticity that comes from its random waves and curls. But apart from a purely tactile response, can we take a more quantitative approach to hair, to explain these macroscopic properties in terms of the behaviour of individual hairs? We know that the important physics governing hair involves the interplay of its elasticity, weight, and curliness, but it is only recently that these have been synthesized into a mathematical theory. This talk will cover those recent advances in the description of physical fiber bundles, including the "Ponytail shape equation" and aspects of "Hairodynamics".

Tuesday 18 April 2017, 14:00 at APC, 483 A - Malevitch APC-TH (Seminar of the theory group of APC) hep-th
Andrei Belokogne ( APC ) Stueckelberg massive electromagnetism in de Sitter and anti-de Sitter spacetimes: Two-point functions and renormalized stress-energy tensors
Abstract: We discuss Stueckelberg massive electromagnetism on an arbitrary four-dimensional curved spacetime. By considering Hadamard vacuum states, we construct the two-point functions associated with Stueckelberg massive electromagnetism in de Sitter and anti-de Sitter spacetimes. We present the Hadamard renormalization of the expectation value of the stress-energy-tensor operator, and we provide its explicit expression for the Stueckelberg theory. By using this general result, we obtain an exact analytical expression for the renormalized vacuum expectation value of the stress-energy tensor of the massive vector field propagating in de Sitter and anti-de Sitter spacetimes. These results could have interesting implications in cosmology of the very early universe or in the context of the AdS/CFT correspondence.

Wednesday 19 April 2017, 14:15 at IPHT, Salle Claude Itzykson, Bât. 774 IPHT-MAT (Séminaire de matrices, cordes et géométries aléatoires) hep-th
Joris Raeymaekers ( Prague Institute of Physics ) (TBA)

Thursday 20 April 2017, 10:00 at IHP, 314 RENC-THEO (Rencontres Théoriciennes) hep-th
Vasilis Niarchos ( Durham ) Aspects of Berry phase in QFT
Abstract: Berry phase is a well-known feature of quantum mechanics. In this talk I will describe several new results about Berry phase in quantum field theory. We will see that even simple quantum field theories can exhibit non-trivial Berry phases and will discuss an explicit example in axion electrodynamics. We will also discuss a general relation between the Berry connection in conformal field theories and the connections on conformal manifolds considered previously by several authors in conformal perturbation theory. The implementation of this relation in 2d N=(2,2) and 4d N=2 superconformal field theories leads to a useful re-derivation of the tt* equations. The latter have important implications on the non-perturbative structure of certain correlation functions, which I will briefly review.

seminars from series at institute
in subject with field matching

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