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Friday 1 December 2017, 10:30 at IHES, Amphithéâtre Léon Motchane
( Cours de l'IHES )
MATH-IHES (TBA) hep-th
Vincent Vargas ( ENS, Paris ) Liouville conformal field theory and the DOZZ formula (4/4)
Abstract: Liouville conformal field theory (LCFT hereafter), introduced by Polyakov in his 1981 seminal work "Quantum geometry of bosonic strings", can be seen as a random version of the theory of Riemann surfaces. LCFT appears in Polyakov's work as a 2d version of the Feynman path integral with an exponential interaction term. Since then, LCFT has emerged in a wide variety of contexts in the physics literature and in particular recently in relation with 4d supersymmetric gauge theories (via the AGT conjecture). A major issue in theoretical physics was to solve the theory, namely compute the correlation functions. In this direction, an intriguing formula for the three point correlations of LCFT was proposed in the middle of the 90's by Dorn-Otto and Zamolodchikov-Zamolodchikov, the celebrated DOZZ formula. The purpose of the course is twofold (based on joint works with F. David, A. Kupiainen and R. Rhodes). First, I will present a rigorous probabilistic construction of Polyakov's path integral formulation of LCFT. The construction is based on the Gaussian Free Field. Second, I will show that the three point correlation functions of the probabilistic construction indeed satisfy the DOZZ formula. This establishes an explicit link between probability theory (or statistical physics) and the so-called conformal bootstrap approach of LCFT.

Friday 1 December 2017, 14:00 at LPTHE, Library LPTHE-PPH (Particle Physics at LPTHE) hep-ph
Glennys Farrar ( CCPP - NY U. ) Sexaquark Dark Matter
Abstract: There may be a so-far-undiscovered neutral, stable particle composed of 6 quarks, denoted S, with mass m_S ~ 2 m_p. If so, the S is an excellent Dark Matter candidate. I will explain why such a particle would not have been detected, propose experiments to discover it, discuss why direct detection experiments to date do not exclude it, mention some of the numerous astrophysical benefits of a DM-baryon interaction, and how it works cosmologically giving the observed DM-baryon abundance ratio and the baryon asymmetry of the Universe.

Monday 4 December 2017, 14:30 at IHES, Amphithéâtre Léon Motchane
( Séminaire Géométrie et groupes discrets )
MATH-IHES (TBA) hep-th
Martin Deraux ( Université Grenoble Alpes ) Spherical CR structures on 3-manifolds
Abstract: : A spherical CR structure on a 3-manifold is a geometric structure modeled on the boundary at infinity of the complex hyperbolic plane, or in other words a (G,X)-structure with G=PU(2,1), X=S^3. I will discuss spherical CR uniformizations, which are a special kind of spherical CR structure that arises by taking the manifold at infinity of a quotient of the ball by the action of a discrete group of isometries. I will explain how to construct some explicit uniformizations, including a 1-parameter family of (pairwise non-conjugate) spherical CR uniformizations of the figure eight knot complement.

Monday 4 December 2017, 16:30 at IHES, Amphithéâtre Léon Motchane
( Séminaire Géométrie et groupes discrets )
MATH-IHES (TBA) hep-th
Matias Carrasco ( (Universidad de la Republica, Montevideo) ) Dimension drop of the harmonic measure of some hyperbolic random walks
Abstract: We consider the simple random walk on two types of tilings of the hyperbolic plane. The first by 2π⁄q-angled regular polygons, and the second by the Voronoi tiling associated to a random discrete set of the hyperbolic plane, the Poisson point process. In the second case, we assume that there are on average λ points per unit area. In both cases the random walk (almost surely) escapes to infinity with positive speed, and thus converges to a point on the circle. The distribution of this limit point is called the harmonic measure of the walk. I will show that the Hausdorff dimension of the harmonic measure is strictly smaller than 1, for q sufficiently large in the Fuchsian case, and for λ sufficiently small in the Poisson case. In particular, the harmonic measure is singular with respect to the Lebesgue measure on the circle in these two cases. The proof is based on a Furstenberg type formula for the speed together with an upper bound for the Hausdorff dimension by the ratio between the entropy and the speed of the walk. This is joint work with P. Lessa and E. Paquette.

Tuesday 5 December 2017, 11:30 at LPTENS, LPTENS library STR-LPT-ENS-HE (Séminaire commun LPTENS/LPTHE) hep-th
Marcos Crichigno ( University of Amsterdam ) TBA
Abstract: TBA

Tuesday 5 December 2017, 14:00 at APC, 483 A - Malevitch APC-TH (Seminar of the theory group of APC) hep-th
Daniel Kroff Fogaça ( CPHT-X ) TBA

Tuesday 5 December 2017, 14:30 at IHES, Amphithéâtre Léon Motchane PT-IHES (Séminaire de physique théorique de l'IHES) hep-th
Fidel I. Schaposnik Massolo ( Seoul National University & IHES ) Phase Diagram of Planar Matrix Quantum Mechanics, Tensor and SYK Models (arXiv: 1707.03431)
Abstract: In this talk I present the phase diagram of a U(N)^2 x O(D) invariant fermionic planar matrix quantum mechanics (equivalently tensor or complex SYK models) in the new large D limit dominated by melonic graphs. The Schwinger-Dyson equations can have two solutions describing either a "large" black hole phase a la SYK or a "small" black hole with trivial IR behavior. In the strongly coupled region of the mass-temperature plane, there is a line of first order phase transitions between the small and large black hole phases. This line terminates at a new critical point which can be studied numerically in detail. The critical exponents are non-mean-field and different on the two sides of the transition. If time allows, I will compare this to purely bosonic unstable and stable melonic models.

Tuesday 5 December 2017, 16:00 at IPHT, Salle Claude Itzykson, Bât. 774 IPHT-HEP (Séminaire de physique des particules et de cosmologie) hep-ph
Matthias Wilhelm ( Niels Bohr Institute ) The Hagedorn temperature of AdS5/CFT4 via integrability
Abstract: We establish a framework for calculating the Hagedorn temperature of AdS5/CFT4 via integrability. Concretely, we derive the thermodynamic Bethe ansatz equations that yield the Hagedorn temperature of planar N=4 super Yang-Mills theory at any value of the 't Hooft coupling. We solve these equations perturbatively at weak coupling via the associated Y-system, confirming the known results at tree-level and one-loop order as well as deriving the previously unknown two-loop Hagedorn temperature. Finally, we comment on solving the equations at finite coupling.

Thursday 7 December 2017, 11:30 at LPTENS, LPTENS Library STRINT (Strings, integrability and beyond) hep-th
Alexander Molochkov ( Far Eastern Federal University, Russia ) TBA
Abstract: TBA

Thursday 7 December 2017, 14:30 at LPTENS, LPTENS Library STRINT (Strings, integrability and beyond) hep-th
Francesco Ravanini ( Bologna University ) TBA
Abstract: TBA

Thursday 7 December 2017, 16:00 at LPT, 114 LPT-PTH (Particle Theory Seminar of LPT Orsay) hep-ph
Darius Faroughy ( Jožef Stefan Institute, Ljubljana ) Confronting hints of new physics in semi-leptonic B-decays with direct searches at the LHC
Abstract: In recent years, hints of lepton flavor universality (LFU) violation in B-physics have apeared in different experimental measurements. In particular, large deviations from the SM predictions in semi-leptonic B-decays have been reported by Belle, BaBar and LHCb in the R_D(*) ratios for b —>c transitions, and more recently by LHCb in the R_K(*) ratios for b—>s transitions. In the meanwhile, a huge amount of theoretical work has been put forward in order to explain these experimental discrepancies with physics beyond the SM. In this talk we argue that high energy experiments at the LHC are capable of probing at current luminosities many of these models by directly searching for new heavy states in neutral currents. As an example we focus on R_D(*) and show, by using model independent arguments and simplified models, that existing data from LHC searches in high-mass ττ tails pose a serious challenge to many BSM solutions. Finally, we briefly discuss recent attempts of building a UV complete model that can explain simultaneously R_D(*) and R_K(*).

Friday 8 December 2017, 10:00 at IPHT, Salle Claude Itzykson, Bât. 774
( https://courses.ipht.cnrs.fr/?q=fr/node/194 )
COURS (Cours) cond-mat
Pierfrancesco Urbani ( IPhT ) Statistical physics of glassy systems: tools and applications (5/6)
Abstract: The complex behavior of a large variety of systems can often be ascribed to the competition of many quasi-optimal equilibria. In these cases metastability deeply affects both the structural and dynamical properties. Glasses are the prototype of such systems, with glassy behavior arising not only in condensed matter but also in a wide variety of fields ranging from optimization to computer science. \par In these lectures I will introduce different kinds of glassy systems and I will describe their fundamental similarities, which emerge from their statistical description. Then I will focus on a representative model, the random perceptron, and I will discuss the main techniques that can be used to solve it. \par These techniques provide a versatile theoretical toolbox that can be applied to several problems such as for example the physics of the jamming transition, its interpretation in the context of constraint satisfaction, as well as the design of new efficient algorithms to solve statistical problems. \\ 1.Introduction to glassy systems: structural glasses and constraint satisfaction problems. \\ 2.The random perceptron model. The replica approach. The replica symmetric solution and phase diagram. \\ 3.Replica symmetry breaking and marginal stability. The full RSB solution of the random perceptron. \\ 4.The jamming transition as a satisfiability threshold; critical exponents. \\ 5.Belief propagation approach and the algorithmic version of the Thouless-Anderson-Palmer equations. \\ Supported by ``Investissements d'Avenir'' LabEx PALM (ANR-10-LABX-0039-PALM)
Attachments:
  • 2017-2018.pdf (4503344 bytes) OPEN
  • 2017_Urbani.pdf (5052625 bytes) OPEN

Tuesday 12 December 2017, 11:30 at LPTENS, LPTENS library STR-LPT-ENS-HE (Séminaire commun LPTENS/LPTHE) hep-th
Sameer Murthy ( King's College London ) TBA
Abstract: TBA

Tuesday 12 December 2017, 14:00 at APC, 483 A - Malevitch APC-TH (Seminar of the theory group of APC) hep-th
Camille Bonvin ( Université de Genève ) TBA

Tuesday 12 December 2017, 17:15 at DPT-PHYS-ENS, Salle Jean Jaurès (29 rue d'Ulm) SEM-PHYS-ENS (Colloquium du Département de Physique de l'ENS) quant-ph
Mark Kasevich ( Stanford University ) TBA

Wednesday 13 December 2017, 10:00 at IHES, Centre de conférences Marilyn et James Simons
( Séminaire de Géométrie Arithmétique Paris-Pékin-Tokyo )
MATH-IHES (TBA) hep-th
J. Fresan ( Ecole polytechnique & IHES ) Exponential motives
Abstract: What motives are to algebraic varieties, exponential motives are to pairs (X, f) consisting of an algebraic variety over some field k and a regular function f on X. In characteristic zero, one is naturally led to define the de Rham and rapid decay cohomology of such pairs when dealing with numbers like the special values of the gamma function or the Euler constant gamma which are not expected to be periods in the usual sense. Over finite fields, the étale and rigid cohomology groups of (X, f) play a pivotal role in the study of exponential sums.  Following ideas of Katz, Kontsevich, and Nori, we construct a Tannakian category of exponential motives when k is a subfield of the complex numbers. This allows one to attach to exponential periods a Galois group that conjecturally governs all algebraic relations among them. The category is equipped with a Hodge realisation functor with values in mixed Hodge modules over the affine line and, if k is a number field, with an étale realisation related to exponential sums. This is a joint work with Peter Jossen (ETH).

Wednesday 13 December 2017, 13:45 at LKB, Collège de France, salle 2 SEM-PHYS-ENS (Colloquium du Département de Physique de l'ENS) quant-ph
Mark Kasevich ( Stanford, USA ) Quantum measurement strategies for atoms, photons and electrons
Abstract: Quantum measurement protocols based on dispersive cavity-assisted interactions will be described. We will show how these protocols lead to performance improvements for precision atomic sensors and to new tests of quantum mechanics. We will also describe quantum imaging methods based on repeated coherent interactions in degenerate optical and electron cavities.

Wednesday 13 December 2017, 14:00 at LPT, Amphi 1, bat 210, 2eme etage, LPT Orsay SOUTEN-TH (Soutenance de thèse) hep-ph
Robert Salazar ( LPT Orsay/Universidad Los Andes (Colombie) ) Resultats exacts et mecanismes de fusion pour les systemes bidimensionnels

Thursday 14 December 2017, 10:00 at IHP, 314 RENC-THEO (Rencontres Théoriciennes) hep-th
Giuseppe Dibitetto ( Uppsala University ) About the (in)stability of stringy AdS vacua
Abstract: I will first briefly review the mechanism of bubble nucleation as a possible instability channel for AdS vacua. Secondly I will discuss it in the specific context of effective supergravity models arising from string compactifications truncated to their closed string sector. By making use of positive energy theorems, I will show that such instabilities do not really occur within this setup. Finally, I will discuss the relation between the above analysis and the weak gravity conjecture (WGC) and will eventually argue that some expected universal instabilities for non-supersymmetric AdS are crucially linked to the coupling between open and closed string sector.

Thursday 14 December 2017, 11:45 at IHP, 314 RENC-THEO (Rencontres Théoriciennes) hep-th
Michal Spalinski TBA

Friday 15 December 2017, 10:00 at IPHT, Salle Claude Itzykson, Bât. 774
( https://courses.ipht.cnrs.fr/?q=fr/node/194 )
COURS (Cours) cond-mat
Pierfrancesco Urbani ( IPhT ) Statistical physics of glassy systems: tools and applications (6/6)
Abstract: The complex behavior of a large variety of systems can often be ascribed to the competition of many quasi-optimal equilibria. In these cases metastability deeply affects both the structural and dynamical properties. Glasses are the prototype of such systems, with glassy behavior arising not only in condensed matter but also in a wide variety of fields ranging from optimization to computer science. \par In these lectures I will introduce different kinds of glassy systems and I will describe their fundamental similarities, which emerge from their statistical description. Then I will focus on a representative model, the random perceptron, and I will discuss the main techniques that can be used to solve it. \par These techniques provide a versatile theoretical toolbox that can be applied to several problems such as for example the physics of the jamming transition, its interpretation in the context of constraint satisfaction, as well as the design of new efficient algorithms to solve statistical problems. \\ 1.Introduction to glassy systems: structural glasses and constraint satisfaction problems. \\ 2.The random perceptron model. The replica approach. The replica symmetric solution and phase diagram. \\ 3.Replica symmetry breaking and marginal stability. The full RSB solution of the random perceptron. \\ 4.The jamming transition as a satisfiability threshold; critical exponents. \\ 5.Belief propagation approach and the algorithmic version of the Thouless-Anderson-Palmer equations. \\ Supported by ``Investissements d'Avenir'' LabEx PALM (ANR-10-LABX-0039-PALM)
Attachments:
  • 2017-2018.pdf (4503344 bytes) OPEN
  • 2017_Urbani.pdf (5052625 bytes) OPEN

Monday 18 December 2017, 14:00 at IPHT, Salle Claude Itzykson, Bât. 774 IPHT-STA (Séminaire de Physique Statistique, CEA/Saclay) cond-mat
Olivier Parcollet ( IPhT ) (TBA)

Tuesday 19 December 2017, 14:00 at LPTENS, LPTENS library STR-LPT-ENS-HE (Séminaire commun LPTENS/LPTHE) hep-th
Dalimil Mazac ( Stony Brook ) TBA
Abstract: TBA

Tuesday 19 December 2017, 14:00 at APC, 483 A - Malevitch APC-TH (Seminar of the theory group of APC) hep-th
Andrei Neronov ( Geneva Observatory ) TBA

Tuesday 19 December 2017, 14:30 at IHES, Amphithéâtre Léon Motchane PT-IHES (Séminaire de physique théorique de l'IHES) hep-th
Emil Akhmedov ( ITEP ) Surprises of quantization in de Sitter space
Abstract: I will talk about loop infrared effects in de Sitter QFT. Namely about their types, physical meaning and origin and also about their resumation and physical consequences. The talk is based on arXiv:1701.07226.

Thursday 11 January 2018, 11:45 at IHP, 314 RENC-THEO (Rencontres Théoriciennes) hep-th
Sergei Dubovsky ( New York University ) Towards a theory of confining strings
Abstract: We put forward the Axionic String Ansatz (ASA), which provides a unified description for the worldsheet dynamics of confining strings in pure Yang--Mills theory both in $D=3$ and $D=4$ space-time dimensions. The ASA is motivated by the excitation spectrum of long confining strings, as measured on a lattice, and by recently constructed integrable axionic non-critical string models. According to the ASA, pure gluodynamics in 3D is described by a non-critical bosonic string theory without any extra local worldsheet degrees of freedom. We argue that this assumption fixes the set of quantum numbers (spins, $P$- and $C$-parities) of almost all glueball states. We confront the resulting predictions with the properties of approximately $1^2+2^2+3^2+5^2=39$ lightest glueball states measured on a lattice and find a good agreement.

Friday 12 January 2018, 10:00 at IPHT, Salle Claude Itzykson, Bât. 774
( https://courses.ipht.cnrs.fr/?q=fr/node/195 )
COURS (Cours) math.AG
Bertrand Eynard ( IPhT ) Riemann surfaces (1/5)
Abstract: (TBA)
Attachments:
  • 2017-2018.pdf (4503344 bytes) OPEN

Tuesday 16 January 2018, 11:30 at LPTENS, LPTENS library STR-LPT-ENS-HE (Séminaire commun LPTENS/LPTHE) hep-th
David Vegh TBA
Abstract: TBA

Tuesday 16 January 2018, 14:00 at APC, 483 A - Malevitch APC-TH (Seminar of the theory group of APC) hep-th
Sebastien Garcia-Saenz ( IAP ) TBA

Thursday 18 January 2018, 11:00 at LPTHE, bibliothèque SEM-DARBOUX (Séminaire Darboux - physique théorique et mathématiques) math|math.MP
David Hernandez ( IMJ-PRG ) TBA

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