Strings: Monday, 07/04/2025, 14:00, Room 226
Diego Trancanelli (University of Modena, Modena)
Conformal defects and RG flows in ABJM
Defects play a central role in many contexts, from condensed matter to quantum gravity. The situations in which the bulk theory is conformal and the defect inherits part of this symmetry -- the so-called defect conformal field theories (dCFTs) -- have recently received a lot of attention, also thanks to new powerful methods to tackle them, like supersymmetric localization, integrability or the bootstrap. A dCFT may be deformed by turning on marginally relevant operators, which trigger RG flows connecting different fixed points. A natural arena where this phenomenon can be explored are 3-dimensional Chern-Simons theories coupled to matter. These are in fact known to display a plethora of Wilson loops that can be used to define 1-dimensional dCFTs living on their contours. In this talk we discuss a few examples from an intricate web of RG flows connecting the dCFTs defined on the BPS and non-BPS Wilson loops of ABJM theory. We compute the anomalous dimensions of the deforming operators, establish g-theorems along the flows, and also discuss the role played by cohomological anomalies and framing. Based on: 2211.16501, 2305.01647, 2312.13283, 2410.10970.
Cosmo: Wednesday, 16/04/2025, 11:30, Slov - "Sál A. Kochanovské" - část A (podium) Solid/1.NP/P.23/1
Natalie Hogg (University of Montpellier)
The weak lensing of strong lensing: a new probe of cosmology
Both weak and strong gravitational lensing have been used to constrain cosmology, via measurements of the clustering parameter S8 with cosmic shear, and measurements of the Hubble parameter H0 and dark energy equation of state w with strong lensing time delays. However, strong lensing images are themselves weakly lensed, and this 'weak lensing of strong lensing' has the potential to become a powerful cosmic probe in its own right. In this talk, I will review the so-called line-of-sight formalism which describes the weak lensing of strong lensing, show how the line-of-sight shear escapes from degeneracies with other lens model parameters, and present the first measurement of this quantity in 50 strong gravitational lenses from the SLACS catalogue. I will also provide a taster of JWST's incredible strong lens detection abilities by concluding my talk with an overview of the COSMOS-Web Lens Survey.
Strings: Monday, 05/05/2025, 14:00, Room 226
Giuseppe Policastro (Ecole Normale Supérieure, Paris)
Energy transport in 2D holographic conformal and non-conformal interfaces
Defects and interfaces are the subjects of intense study in different contexts, as they provide useful probes quantum field theory and condensed-matter systems. In the case of two-dimensional conformal interfaces, universal properties are encoded in the flux of energy transmitted and reflected for an excitation scattering with the interface. I will discuss the study of energy trasport across interfaces in the holographic setup, using the minimal holographic model of a brane in AdS3, and extended brane configurations that can mimic top-down smooth gravity solutions, and the extension to a class of non-conformal defects obtained by turning on a TTbar-deformation of the CFT.
Cosmo: Wednesday, 24/04/2025, 11:30, Lecture Room
Gabriele Franciolini (University of Pisa)
TBA
Cosmo: Wednesday, 14/05/2025, 11:30, Lecture Room
Oindrila Ghosh (Stockholm University) (TBC)
TBA
Strings: Monday, 12/05/2025, 14:00, Room 226
Subhroneel Chakrabarti (Masaryk University, Brno)
TBA
Cosmo: Wednesday, 28/05/2025, 11:30, Lecture Room
Jose M Ezquiaga (University of Copenhagen) (TBC)
TBA
Strings: Monday, 19/05/2025, 14:00, Solid Lecture Hall
Valery Frolov (University of Alberta, Canada)
TBA
Strings: Monday, 26/05/2025, 14:00, Room 226
Seyed Morteza Hosseini (Queen Mary University of London, London)
TBA
Cosmo: Wednesday 21/05/2025, 11:30, Lecture Room
Guillermo Franco-Abellan (Amsterdam University)
TBA
Strings: Monday, 09/06/2025, 14:00, Room-226
Debashis Ghoshal (Harish-Chandra Research Institute, Allahabad)
TBA
Strings: Monday, 16/06/2025, 14:00, Room 226
Andrea De Marco (Charles University & CEICO, Prague)
TBA