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  
[ scheduler view ] 
Monday 25 January 2021, 10:45 at
LPTMC,
online zoom seminar ( https://zoom.us/j/95256910532 ID de réunion : 952 5691 0532 Code secret : 141152 )  SEMLPTMC (Séminaire du Laboratoire de Physique Théorique de la Matière Condensée)  condmat.meshall 



Abstract:  Manybody localization is a way to break ergodicity, thermalization and transport in disordered interacting quantum systems.The existence of a manybody localization transition in 2D systems is an open question that is being addressed experimentally, theoretically and numerically. In this talk, I will show some recent numerical results for a model whose features make it especially accessible to exact diagonalization. We numerically study the possibility of manybody localization transition in a constrained system: a disordered quantum dimer model on the honeycomb lattice. By using the peculiar constraints of this model and stateoftheart exact diagonalization and time evolution methods, we probe large twodimensional systems of up to N=108 sites. F Pietracaprina and F Alet, Arxiv Preprint arXiv:2005.10233 [condmat.disnn] (2020) 
Monday 25 January 2021, 11:00 at IPHT, (voir dans annonce)  IPHTPHM (Séminaire de physique mathématique)  mathph 



Abstract:  I will start with a brief review of the irrelevant currentcurrent deformations of twodimensional QFTs introduced by Smirnov and Zamolodchikov, concentrating on the $T\bar T, J\bar T $ and $ JT_a$ ones. I will then show that classical $T\bar T, J\bar T $ and $ JT_a$ deformed CFTs possess an infinite set of symmetries that take the form of a field dependent generalization of twodimensional conformal and, if applicable, $U(1)$ transformations. The Poisson bracket algebra of the associated conserved charges consists of two commuting copies of a functional Witt  (Ka\v{c}Moody) algebra. One notes, however, that at semiclassical level on a cylinder, the equal spacing of the descendants' energies predicted by such a symmetry algebra is inconsistent with the known finitesize spectrum of the deformed CFTs. I will show how to resolve this tension in the specific case of $J\bar T$  deformed CFTs, by exhibiting a new set of (classical) conserved charges, which are related to the previous symmetry generators by a type of energydependent spectral flow. The above results suggest then that $T\bar T, J\bar T $ and $ JT_a$ deformed CFTs correspond to nonlocal versions of usual twodimensional conformal field theories, a structure that would be interesting to explore further. \\ \\ The seminar is online only. \\ Internet link to be collected from the Organizer: Vincent Pasquier (vincent.pasquier@ipht.fr) 
Monday 25 January 2021, 16:00 at
LPNHE,
Online ( Contact seminaires@lpnhe.in2p3.fr for Zoom link )  LPNHE (Séminaires du LPNHE)  hepex 


Tuesday 26 January 2021, 14:00 at APC, https://unige.zoom.us/j/93722626572  APCTH (Seminar of the theory group of APC)  grqc 



Abstract:  Primordial black holes are a dark matter candidate, which may originate from strong perturbations created during inflation. These perturbations can be studied using the formalism of stochastic inflation. I present a numerical approach to this problem, where the stochastic dynamics is solved by generating a large number of random realizations. This makes it possible to go beyond analytical approximations and take into account additional effects such as backreaction between the perturbations and the background. I show that in an example model with an inflection point potential and ultraslowroll inflation, compatible with CMB measurements, stochastic effects produce a highly nonGaussian tail for the perturbations, which changes the predictions for black hole production significantly. 
Tuesday 26 January 2021, 16:00 at IHP, Seminar via zoom https://ijclab.zoom.us/j/94900481972  P^3 (Particle Physics in Paris)  astrophhepph 



Abstract:  In this talk I will highlight some special experimental capabilities of future liquid argon time projection chamber (LArTPCs) neutrino experiments like the Fermilab’s Short Baseline Neutrino Program and DUNE. I will give a broad overview of what could be gained with these capabilities. Then, I will provide concrete physics opportunities that are enabled by LArTPCs, including measuring the CP violation phase with atmospheric neutrinos, searching for light dark matter, and performing precision electroweak physics measurements. 
Thursday 28 January 2021, 11:00 at
LPTHE,
Zoom and bibliothèque du LPTHE, tour 1314, 4eme étage ( This seminar will be given in hybrid mode. People who wish to attend in person should contact Ander Retolaza. Zoom: https://zoom.us/j/97507124810 (pwd= 1234 ) )  RENCTHEO (Rencontres Théoriciennes)  hepth 



Abstract:  We formulate a series of conjectures relating the geometry of conformal manifolds to the spectrum of local operators in conformal field theories in d>2 spacetime dimensions. We focus on conformal manifolds with limiting points at infinite distance with respect to the Zamolodchikov metric. Our central conjecture is that all theories at infinite distance possess an emergent higherspin symmetry, generated by an infinite tower of currents whose anomalous dimensions vanish exponentially in the distance. Stated geometrically, the diameter of a noncompact conformal manifold must diverge logarithmically in the higherspin gap. Our conjectures are related to the Distance Conjecture in the swampland program. We discuss the supporting evidence, their holographic interpretation, and implications for superconformal field theories. 
Monday 1 February 2021, 10:45 at
LPTMC,
online zoom seminar ( https://zoom.us/j/95015087598 ID de réunion : 950 1508 7598 Code secret : 599922 )  SEMLPTMC (Séminaire du Laboratoire de Physique Théorique de la Matière Condensée)  condmat.meshall 



Abstract:  Our modern understanding of universality, namely the independence of the critical properties of a system from its microscopic details, is based on the ideas put forward by K. Wilson and formalised within the framework of the renormalization group (RG). Despite the centrality of the subject in modern days theoretical Physics and the many decades passed since Wilson's original works, the classification of universality classes is to date largely unsolved. In recent years, however, the functional reformulation of the perturbative RG provided a simple tool to approach such a classification, extending significantly our knowledge of universality classes entailed by discrete symmetry groups in scalar field theories. In this talk, I will first introduce the technique, elucidate its keypoint features and explain why it is so effective in charting the theory space. In passing, I briefly review the theory of invariant polynomials paying particular attention to the socalled Hilbert (or Molien) series. I will then focus on three particular cases: the scalar field theories endowed with the symmetry group of regular polytopes, the randomly diluted Ising models and the more general hypercubic scalar field theories. For each of these three cases, I review the main results and suggest possible lines of future investigations. References: https://arxiv.org/abs/1902.05328 https://arxiv.org/abs/2006.12808 
Tuesday 2 February 2021, 14:00 at APC, https://unige.zoom.us/j/93722626572  APCTH (Seminar of the theory group of APC)  grqc 



Abstract:  Although inflation is broadly accepted to be the standard paradigm for early universe cosmology, many of its quantum properties remain unknown. For instance, the crowning glory of inflation lies in explaining latetime macroscopic inhomogeneities as arising from tiny quantum fluctuations; however, most of the established literature ignores the crucial role that entanglement between the modes of the fluctuating field plays in its observable predictions. In this talk, I shall discuss how treating observable longwavelength modes as part of an open quantum system can significantly affect the dynamics (and detectable consequences) of inflation, even when considering the nonlinearities arising solely from gravity. Since these dissipative effects are at the heart of decoherence (and how quantum fluctuations turn classical), such primordial entanglement is inescapable and provides universal upper bounds on the duration of inflation. 
Tuesday 2 February 2021, 14:00 at LPTHE, Seminar via zoom https://zoom.us/j/95696803823  LPTHEPPH (Particle Physics at LPTHE)  astrophhepphhepth 


Tuesday 2 February 2021, 17:00 at LPTENS, GoToMeeting  STRLPTENSHE (Séminaire commun LPTENS/LPTHE)  hepth 


Thursday 4 February 2021, 11:00 at LPTHE, bibliothèque du LPTHE, tour 1314, 4eme étage  SEMDARBOUX (Séminaire Darboux  physique théorique et mathématiques)  condmathepthmath.MP 



Abstract:  In this talk we review the Ktheoretic description of topological phases of insulators and superconductors in the effective one particle approximation. In that approximation, an insulator (or superconductor) is described by a Hamiltonian whose spectrum has a gap at the Fermi energy. Two Hamiltonians belong to the same topological phase if they can be deformed into each other without closing the gap. For this to be welldefined, it is important to specify the space of possible Hamiltonians with its topology. When this space is taken to be a C*algebra equipped with a real structure and a grading, one can use real graded Ktheory and its dual (Khomology or cyclic cohomology) to describe the topological phases and their numerical topological invariants. 
Friday 5 February 2021, 14:00 at LPTENS, GoToMeeting  STRLPTENSHE (Séminaire commun LPTENS/LPTHE)  hepth 


Monday 8 February 2021, 10:45 at
LPTMC,
online zoom seminar ( https://zoom.us/j/3863193200 ID de réunion : 386 319 3200 Code secret : 044816 )  SEMLPTMC (Séminaire du Laboratoire de Physique Théorique de la Matière Condensée)  condmat.meshall 



Abstract:  TBA 
Tuesday 9 February 2021, 16:00 at
IHP,
Seminar via zoom https://ijclab.zoom.us/j/94900481972 ( This seminar will be followed by the one of Constantinos Skordis (University of Cyprus and Czech Academy of Sciences) at 16:30 )  P^3 (Particle Physics in Paris)  astrophhepphhepth 


Tuesday 9 February 2021, 16:30 at
IHP,
Seminar via zoom https://ijclab.zoom.us/j/94900481972 ( This seminar follows the one at 16:00 by David Spergel (Princeton University) )  P^3 (Particle Physics in Paris)  astrophhepphhepth 


Friday 19 February 2021, 14:00 at LPTENS, GoToMeeting  STRLPTENSHE (Séminaire commun LPTENS/LPTHE)  hepth 


Tuesday 23 February 2021, 16:00 at IHP, Seminar via zoom https://ijclab.zoom.us/j/94900481972  P^3 (Particle Physics in Paris)  hepphhepth 


Friday 5 March 2021, 11:00 at APC, https://uparis.zoom.us/j/84776224570?pwd=ZWNLMEQ0bThsWGJuL0IvbnUxTEpxUT09  APCCOLLOQUIUM (Colloquium de l'APC)  hepth 



Abstract:  TBA 

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