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Friday 9 February 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 (5/5)
Abstract: Algebraic equations are widespread in mathematics and physics, and the geometry of their spaces of solutions can be complicated. In the case of an equation of two complex variables, the space of solutions is a Riemann surface. \par We will provide basic tools (going back to Riemann) for studying algebraic equations and describing the geometry of compact Riemann surfaces. \par We will consider a Riemann surface defined from the solution locus of a polynomial equation $P(x,y)=0$ in $\mathbb{C} \times \mathbb{C}$. We will study its topology and geometry, and learn how to integrate differential forms along closed contours. Then we will describe the moduli space of Riemann surfaces with a given topology: its dimension, topology, etc. \par We will introduce some of the many tools that have been invented since the time of Riemann for studying these objects. We will partly follow the Mumford Tata lectures, the Fay lectures, and the Farkas-Kra book. \\ \\ The plan is: \\ - Compact Riemann surfaces, charts, atlas, toplogy. Meromorphic functions and one-forms. Theorems on poles and residues. Newton's polygon. \\ - Integrals, periods, Abel map, Jacobian, divisors. Theta functions, prime form, fundamental form. Basis of cycles, homology and cohomology. \\ - Moduli spaces of Riemann surfaces. Deligne-Mumford compactification, Chern classes, tautological ring. Kontsevich integral and KdV hierarchy. \\ - If times permits: fiber bundles, Hitchin systems, link to integrable systems.
Attachments:
  • 2017-2018.pdf (4503344 bytes) OPEN
  • 2018_Eynard_0.pdf (4424243 bytes) OPEN

Friday 9 February 2018, 11:00 at LPTHE, Bibliothèque SEM-LPTHE (Séminaire du LPTHE) cond-mat.stat-mech
Sanjay Ramassamy ( ENS Lyon ) Miquel dynamics for circle patterns
Abstract: Circle patterns are one of the ways to uniformize graphs on surfaces, by embedding them in such a way that every face admits a circumcircle. In this talk I will describe a discrete-time dynamical system on circle patterns with the combinatorics of the square grid. This dynamics, based on the classical six-circles theorem of Miquel, is called Miquel dynamics. It was introduced by Richard Kenyon as an attempt to find a connection between circle patterns and the dimer model. I will present some properties of this dynamics which suggest its integrability. Partly joint work with Alexey Glutsyuk (École normale supérieure de Lyon).

Monday 12 February 2018, 10:45 at LPTMC, tower 13-12 5th floor room 5-23 SEM-LPTMC (Séminaire du Laboratoire de Physique Théorique de la Matière Condensée) cond-mat.mes-hall
André Thiaville ( LPS Orsay ) Magnétisme et topologie

Tuesday 13 February 2018, 11:00 at IPHT, Salle Claude Itzykson, Bât. 774 SEM-EXCEP (Séminaire exceptionel) physics
Francis Bernardeau ( IAP et IPhT ) (TBA)

Tuesday 13 February 2018, 14:00 at APC, 483 A - Malevitch APC-TH (Seminar of the theory group of APC) hep-th
Xavier Bekaert ( LMPT, Université de Tours ) TBA

Tuesday 13 February 2018, 16:00 at IPHT, Salle Claude Itzykson, Bât. 774 IPHT-HEP (Séminaire de physique des particules et de cosmologie) hep-ph
Francesco Riva ( CERN and Geneva University ) (TBA)

Wednesday 14 February 2018, 11:30 at IPN, Bâtiment 100, Salle A015
( $ $ )
IPN-THEO (Séminaire du groupe de physique théorique de l'IPN Orsay) nucl-th
Wouter Ryssens ( IPNL ) Towards symmetry-unrestricted Skyrme-HFB: MOCCa and its applications
Abstract: The concept of intrinsic symmetry breaking is central to the mean-field description of nuclei: it allows for the inclusion of correlations beyond the indepent-particle picture at modest computational cost. Restriction of the rotational symmetry to one Cartesian axis (instead of three) is a prime example of intrinsic symmetry breaking in many mean-field approaches; limiting rotational symmetry this way gives acces to the description of axial deformations. While in many applications axial (and to a lesser extent, triaxial) deformations are considered, there remain a number of significant additional symmetries that are assumed to be conserved in many approaches. These assumptions are usually made for two reasons: every conserved intrinsic symmetry eases the computational burden and facilitates the physical interpretation of the results. However, an important downside of conserving additional symmetries is the limitation of the variational space and a loss of generality: the description of exotic geometries is often impossible. An example is reflection symmetry: while assumed to be conserved in many cases, it is necessarily broken for nuclear configurations exhibiting octupole or tetrahedral deformation. With the advent of tracking-$\gamma$-ray spectroscopy, experiments become more and more able to resolve the rich structure of rotational bands in numerous nuclei. More and more data becomes available on bands that are associated in a mean-field context with exotic geometries of the nucleus. To provide a satisfactory mean-field description of such bands, only allowing for axial (or even triaxial) deformations is not sufficient. To improve the description of such states, we have developed a new framework for self-consistent mean-field calculations, using effective Skyrme interactions in a coordinate-space representation. The MOCCa code is a generalization of the principles of the EV8 code, allowing its user for significant freedom concerning symmetry assumptions of the nuclear configuration and a more general treatment of pairing correlations. Breaking signature symmetry in particular presents a new frontier for nuclear density functional theory. Without such assumption, the orientations of various angular momenta at play in the nucleus are no longer restricted by symmetry. This freedom opens up the possibility to study various exotic rotational phenomena such as wobbling excitations and octupole rotational bands, as well as treat quasiparticle excitations in both even and odd-mass nuclei on a more general level. I will first introduce MOCCa and the principles it is built on, highlighting the physical and practical motivations for its construction. Afterwards, I will touch upon past and present challenges when dealing with signature symmetry, specifically with respect to the treatment of pairing, including a discussion on how to solve the Skyrme-HFB equations without any conserved antilinear symmetry. Finally, I will present a set of recent results obtained within this framework, specifically focusing on the freedom obtained by releasing signature symmetry, specifically when dealing with (the rotation of) odd nuclei.
Attachments:
  • 2018_02_14_W_Ryssens.pdf (212037 bytes) OPEN

Friday 16 February 2018, 11:30 at SAMM, C20.13 SAMM (Statistics, Analysis, Multidisciplinary Modeling) CoRR.CY|cond-mat.stat-mech|physics.soc-ph
Claire Lemercier ( CNRS / SciencesPo ) Structure and Dynamics of Migration Patterns in 19th-century Northern France
Abstract: Spatial and relational patterns of intensive rural-urban migration are a major concern in social sciences. We reconstitute migration areas and explain their path-dependent changes through an innovative and easily replicable research strategy. Focusing on the rapid urbanization of 19th-century Northern France, we analyze the long-neglected, yet non-random patterns of movement between villages and explain the exceptionally slow pace of French rural out-migration. The techniques inspired by network analysis complement standard models used in economic geography and allow us to identify the enduring channels of preferential migration between villages as well as the impact of changing socio-economic opportunities. The social differentiation among the possibilities to migrate, along with the interactions between marriage and work-related movements, produce multivariate models of migration field transformations. NB : La présentation sera en français

Tuesday 27 February 2018, 11:30 at LPTENS, LPTENS library STR-LPT-ENS-HE (Séminaire commun LPTENS/LPTHE) hep-th
Elli Pomoni ( DESY ) TBA
Abstract: TBA

Tuesday 6 March 2018, 14:00 at APC, 483 A - Malevitch APC-TH (Seminar of the theory group of APC) hep-th
Sajad Abbar ( APC, Université Paris Diderot ) Collective Neutrino Oscillations in Core-Collpase Supernovae and Neutron Star Mergers

Tuesday 6 March 2018, 16:00 at IPHT, Salle Claude Itzykson, Bât. 774 IPHT-HEP (Séminaire de physique des particules et de cosmologie) hep-ph
Garrett Goon ( ITP Utrecht University ) (TBA)

Tuesday 6 March 2018, 17:15 at DPT-PHYS-ENS, room Jean Jaurès (29 rue d'Ulm) SEM-PHYS-ENS (Colloquium du Département de Physique de l'ENS) astro-ph
Bruce Allen ( Max Planck Institute for Gravitational Physics & U. of Wisconsin-Milwaukee ) The direct observation of gravitational waves
Abstract: For the first time, starting more than two years ago, the advanced LIGO and Virgo instruments have directly observed gravitational waves. The first signals seen were from the mergers of pairs of massive black holes, and more recently we have also observed the inspiral and merger of two neutron stars. I will talk about the history and current status of this field, the basic physics of our observations, and some of our hopes and expectations for the future.

Friday 9 March 2018, 10:00 at IPHT, Salle Claude Itzykson, Bât. 774
( https://courses.ipht.cnrs.fr/?q=fr/node/196 )
COURS (Cours) hep-th
Monica Guica ( IPhT ) Asymptotic symmetries, black holes, and holography (1/5)
Abstract: (TBA)
Attachments:
  • 2017-2018.pdf (4503344 bytes) OPEN

Monday 12 March 2018, 10:45 at LPTMC, tower 13-12 5th floor room 5-23 SEM-LPTMC (Séminaire du Laboratoire de Physique Théorique de la Matière Condensée) cond-mat.mes-hall
Xia-Qing Shi ( Soochow university, China and SPEC-CEA Saclay ) Recent results on dense bacterial suspensions
Abstract: This talk will show that bacterial suspensions, beyond their intrinsic, dominating importance in biology, are also excellent systems to explore and test theoretical results on active matter, I will present recent experimental results on dense bacterial suspensions obtained in the groups of Masaki Sano (University of Tokyo), Yilin Wu (Chinese University of Hong Kong), and Hepeng Zhang (Shanghai Jiaotong University). I will put them in context, situating them within our current knowledge of active matter, stressing differences and similarities. Particular attention will be paid to the modeling efforts already deployed or to be developed in order to understand the fascinating large-scale phenomena observed by these 3 groups.

Tuesday 13 March 2018, 11:30 at LPTHE, LPTHE library STR-LPT-ENS-HE (Séminaire commun LPTENS/LPTHE) hep-th
Eric D'hoker ( UCLA ) TBA
Abstract: TBA

Thursday 15 March 2018, 11:00 at LPTHE, bibliothèque SEM-DARBOUX (Séminaire Darboux - physique théorique et mathématiques) math|math.MP
Oliver Schnetz ( Erlangen ) TBA

Friday 16 March 2018, 10:00 at IPHT, Salle Claude Itzykson, Bât. 774
( https://courses.ipht.cnrs.fr/?q=fr/node/196 )
COURS (Cours) hep-th
Monica Guica ( IPhT ) Asymptotic symmetries, black holes, and holography (2/5)
Abstract: (TBA)
Attachments:
  • 2017-2018.pdf (4503344 bytes) OPEN

Monday 19 March 2018, 14:00 at IPHT, Salle Claude Itzykson, Bât. 774 IPHT-STA (Séminaire de Physique Statistique, CEA/Saclay) cond-mat
Martin Lenz ( LPTMS Orsay ) Slimming down through frustration
Abstract: Controlling the self-assembly of supramolecular structures is vital for living cells, and a central challenge for engineering at the nano- and microscales. Nevertheless, even particles without optimized shapes can robustly form well-defined morphologies. This is the case in numerous medical conditions where normally soluble proteins aggregate into fibers. Beyond the diversity of molecular mechanisms involved, we propose that fibers generically arise from the aggregation of irregular particles with short-range interactions. Using minimal models of frustrated aggregating particles, we demonstrate robust fiber formation for a variety of particle shapes and aggregation conditions. Geometrical frustration plays a crucial role in this process, and accounts for the range of parameters in which fibers form as well as for their metastable, yet long-lived character.

Tuesday 20 March 2018, 17:15 at DPT-PHYS-ENS, room Jean Jaurès (29 rue d'Ulm) SEM-PHYS-ENS (Colloquium du Département de Physique de l'ENS) cond-mat.str-el
Gabriel Kotliar ( Rutgers University ) How to form strongly correlated electron states
Abstract: TBA

Friday 23 March 2018, 10:00 at IPHT, Salle Claude Itzykson, Bât. 774
( https://courses.ipht.cnrs.fr/?q=fr/node/196 )
COURS (Cours) hep-th
Monica Guica ( IPhT ) Asymptotic symmetries, black holes, and holography (3/5)
Abstract: (TBA)
Attachments:
  • 2017-2018.pdf (4503344 bytes) OPEN

Monday 26 March 2018, 10:45 at LPTMC, tower 13-12 room 5-23 SEM-LPTMC (Séminaire du Laboratoire de Physique Théorique de la Matière Condensée) cond-mat.mes-hall
Giulio Biroli ( IPhT Saclay and LPS ENS ) TBA

Tuesday 27 March 2018, 11:30 at LPTENS, LPTENS library STR-LPT-ENS-HE (Séminaire commun LPTENS/LPTHE) hep-th
Apratim Kaviraj ( LPTENS ) TBA
Abstract: TBA

Thursday 29 March 2018, 11:00 at LPTHE, bibliothèque SEM-DARBOUX (Séminaire Darboux - physique théorique et mathématiques) math|math.MP
Nicolas Bergeron ( IMG-PRG ) TBA

Friday 30 March 2018, 10:00 at IPHT, Salle Claude Itzykson, Bât. 774
( https://courses.ipht.cnrs.fr/?q=fr/node/196 )
COURS (Cours) hep-th
Monica Guica ( IPhT ) Asymptotic symmetries, black holes, and holography (4/5)
Abstract: (TBA)
Attachments:
  • 2017-2018.pdf (4503344 bytes) OPEN

Tuesday 3 April 2018, 11:00 at IPHT, Salle Claude Itzykson, Bât. 774 IPHT-GEN (Séminaire général du SPhT) physics
Slava Rychkov ( CERN and IHES ) (TBA)

Tuesday 3 April 2018, 17:15 at DPT-PHYS-ENS, room Jean Jaurès (29 rue d'Ulm) SEM-PHYS-ENS (Colloquium du Département de Physique de l'ENS) quant-ph
Sabrina Maniscalco ( University of Turku ) TBA
Abstract: TBA

Thursday 5 April 2018, 10:00 at IHP, 314 RENC-THEO (Rencontres Théoriciennes) hep-th
Oscar Dias ( Southampton ) TBA

Thursday 5 April 2018, 11:45 at IHP, 314 RENC-THEO (Rencontres Théoriciennes) hep-th
James Sparks ( Oxford ) TBA

Friday 6 April 2018, 10:00 at IPHT, Salle Claude Itzykson, Bât. 774
( https://courses.ipht.cnrs.fr/?q=fr/node/196 )
COURS (Cours) hep-th
Monica Guica ( IPhT ) Asymptotic symmetries, black holes, and holography (5/5)
Abstract: (TBA)
Attachments:
  • 2017-2018.pdf (4503344 bytes) OPEN

Monday 9 April 2018, 14:00 at IPHT, Salle Claude Itzykson, Bât. 774 IPHT-STA (Séminaire de Physique Statistique, CEA/Saclay) cond-mat
Juan P. Garrahan ( University of Nottingham ) (TBA)

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