Fukaya category for Landau-Ginzburg orbifolds and Berglund-Hübsch homological mirror symmetry for curve singularities

Cheol-Hyun Cho
Seoul National University
September 21, 2020
For a weighted homogeneous polynomial and a choice of a diagonal symmetry group, we define a new Fukaya category based on wrapped Fukaya category of its Milnor fiber together with monodromy information. It is analogous to the variation operator in singularity theory. As an application, we formulate a complete version of Berglund-Hübsch homological mirror symmetry and prove it for two variable cases.

Light-rays and detectors in Wilson-Fisher theory

Petr Kravchuk
Member, School of Natural Sciences, IAS
September 18, 2020
In conformal field theory, in contrast to gapped theories, S-matrix is not well-defined. Similarly, various inclusive observables which make sense in a gapped theory, such as "energy squared" calorimeters, suffer from IR divergences in CFTs. Using the example of Wilson-Fisher theory, I will discuss how these observables can be renormalized and what is the physical meaning of their anomalous dimensions.

Broué’s Abelian Defect Group Conjecture II

Daniel Juteau
Centre National de la Recherche Scientifique/Université Paris Diderot; Member, School of Mathematics
September 17, 2020
In this second talk about Broué’s Abelian Defect Group Conjecture, we will explain its geometric version in the case of finite groups of Lie type: the equivalence should be induced by the cohomology complex of Deligne-Lusztig varieties. This was actually the main motivation for the conjecture in the first place. We will illustrate those ideas with the case of SL(2,q).

Turbulent power-law spectra in the universe

Siyao Xu
IAS
September 17, 2020
Turbulence is ubiquitous in astrophysical media and plays an essential role in a variety of fundamental astrophysical processes. The turbulent power-law spectra have been observed in the solar wind, the interstellar medium, the intracluster medium, over a vast range of length scales. In our Galaxy, I will discuss pulsars as a unique tool for statistically studying the turbulence in the multi-phase interstellar medium over different ranges of length scales.

Simulating Multiscale Astrophysics to Understand Galaxy formation

Rachel Somerville
Rutgers University; Flatiron Institute
September 15, 2020
Building genuinely a priori models of galaxy formation in a cosmological context is one of the grand challenges of modern astrophysics. Most large volume simulations of galaxy formation currently adopt phenomenological scaling relations to model "small scale" processes such as star formation, stellar feedback, and black hole formation, growth, and feedback, which limits their predictive power.

Reeb dynamics in dimension 3 and broken book decompositions

Vincent Colin
Université de Nantes
September 11, 2020
In a joint work with Pierre Dehornoy and Ana Rechtman, we prove that on a closed 3-manifold, every nondegenerate Reeb vector field is supported by a broken book decomposition. From this property, we deduce that in dimension 3 every nondegenerate Reeb vector field has either 2 or infinitely periodic orbits and that on a closed 3-manifold that is not graphed, every nondegenerate Reeb vector field has positive topological entropy.