Talks

The notion of singular support for coherent sheaves was introduced by Arinkin and Gaitsgory in order to carefully state the geometric Langlands conjecture.  This is a conjectural equivalence of categories of sheaves on certain moduli spaces: in order to make the conjecture reasonable one needs to restrict to sheaves which satisfy a certain "singular support condition".  In this talk I'll explain how to think about this singular support condition from the point of view of boundary conditions in twisted N=4 gauge theory.  Specifically, Arinkin and Gaitsgory's singular support condition arises by considering only those boundary conditions which are compatible with a natural choice of vacuum state.  By allowing this vacuum state to move away from this natural choice we see aspects of a rich additional structure for the geometric Langlands correspondence.  This work is joint with Philsang Yoo.

Any quantum field theory can be thought of as arising from a perturbed UV conformal field theory, suggesting that information about the full RG flow is encoded in the original CFT. I will discuss ongoing work developing new methods for extracting this information to study strongly-coupled IR dynamics. This method uses a UV basis of conformal Casimir eigenstates to construct the Hamiltonian, which is then truncated at some maximum Casimir eigenvalue and diagonalized to approximate the low energy spectrum of the IR theory. After presenting a general framework which can be applied to CFTs in any number of dimensions, I will then focus on the specific example of scalar field theory, which can be used to study strongly-coupled systems like the 2D and 3D Ising models. Finally, I will discuss the possible application of this framework to gauge theories, including QCD.

I will discuss the role(s) of the Immirzi parameter in Loop Quantum Gravity, insisting on the Poisson algebra formed by Thiemann's complexifier, the volume and the Hamiltonian constraint. In particular, we will see how loop quantum cosmology is a direct quantization of this CVH Poisson algebra and how cosmological evolution amounts to a flow in the Immirzi parameter.

I will first show that a number of persistent astrophysical puzzles, including missing pulsars in the galactic center, fast radio bursts, the abundance of r-process elements, and the type Ia supernova progenitor problem, may all be an emerging signature of dark matter. I will address some theoretical implications and new astrophysical phenomena -- for example "quiet kilonovae" and "r-process donuts" -- associated with this dark matter. Then, I will describe a newly discovered effect, that dark matter crashing into neutron stars warms them to infrared temperatures detectable with the Thirty Meter, European Extremely Large, and James Webb Space telescopes.

Gravitational lensing is one of the primary investigation tools of all current and future wide field surveys. In this talk I will review its current status (with the Kilo Degree Survey (KiDS)) and show what unique cosmological information it gives us. Lensing is not limited to a, low redshift, dark universe probe, it can also be used as a tool to probe baryons and nicely work in synergy with baryonic probes (e.g. CMB, Xray, tSZ, HI). I will show some of the work in progress to help constraining Active Galactic Nuclei feedback