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 at LPTHE  
[ scheduler view ] 
Thursday 24 May 2018, 11:00 at LPTHE, bibliothèque  SEMDARBOUX (Séminaire Darboux  physique théorique et mathématiques)  mathmath.MP 



Abstract:  We will first recall the general framework of cluster algebras and cluster varieties attached to arbitrary quivers. We will then explain what can be said about interesting differential forms on these varieties when the quiver is a tree, and how counting points over finite fields gives a first idea about their cohomology. This will be illustrated with examples, and involve an amusing set of Feynman rules with 3 colors. 
Thursday 24 May 2018, 14:00 at LPTHE, Library  LPTHEPPH (Particle Physics at LPTHE)  hepph 



Abstract:  There are some discrepancies with respect to Standard Model predictions in measurements of $b$meson decays. After reviewing the discrepancies and effective field theory fits, we examine simplified models of new physics that may explain a subset of them: in particular, $B \rightarrow K^{(\ast)} \mu^+ \mu^$. There are two such classes of model that explain the discrepancies at treelevel: leptoquarks or $Z^\prime$ models. We then examine the prospects of detecting these two explanations at future colliders: the future circular collider and the high luminosity or high energy versions of the LHC. 
Friday 25 May 2018, 11:00 at LPTHE, Bibliothèque  SEMLPTHE (Séminaire du LPTHE)  condmat.statmech 



Abstract:  In this talk, I will discuss a theoretical framework for understanding materials that are fragile. These are marginal solids or highly viscous liquids that emerge out of thermal equilibrium in response to external stresses. Granular materials and nonBrownian colloidal suspensions are wellknown examples, however, reconfigurable pathways of force transmission also play an important role in biological systems. In granular materials, external forces such as gravity create rigid and flowing states. The mechanical integrity of these marginal solids is reliant on a filamentary network of stressbearing structures. An outstanding question in the field has been how the constraints of vectorial force balance influence the response of granular assemblies to stress, and create localized stress pathways. I will present results of recent work showing that the localized response is a consequence of the disorder in the underlying contact network, and can be mapped on to a ``localization'' problem. I will also discuss an interpretive theory, based on statistical ensembles, of two transitions driven by frictional contacts: shear jamming and discontinuous shear thickening. 
Thursday 31 May 2018, 10:00 at IHP, 314  RENCTHEO (Rencontres Théoriciennes)  hepth 


Thursday 31 May 2018, 11:45 at IHP, 314  RENCTHEO (Rencontres Théoriciennes)  hepth 



[ English version ] 