The Rényi entanglement entropy of quantum many-body systems can be viewed as the difference in free energy of partition functions with different trace topologies. We introduce an external field λ that controls the partition function topology, allowing us to define a notion of nonequilibrium work as λ is varied smoothly. Nonequilibrium fluctuation theorems of the work provide us with statistically exact estimates of the Rényi entanglement entropy. We put these ideas to use in the context of quantum Monte Carlo simulations of SU(N) symmetric spin models in one and two dimensions. In both cases we detect logarithmic violations to the area law with high precision, allowing us to extract the central charge for the critical 1D models and the number of Goldstone modes for the magnetically ordered 2D models.

I will discuss global quenches in a number of interacting quantum field theory models away from the conformal regime. The scaling of various observables at early times will be presented with a particular emphasis placed on the leading order effects that cannot be recovered using the finite order conformal perturbation theory. At the end I will discuss potential route towards understanding the late time dynamics using the canonical ideas of effective action.

In this talk I shall be describing how to obtain planar scattering amplitudes of quartic massless scalar theory from some particular positive geometries known as Stokes polytopes. The residues of the canonical form on these Stokes polytopes can be used to compute scattering amplitudes for quartic interactions. Properties like locality and unitarity of the amplitudes will be manifest from the geometric properties of the Stokes polytopes.

The SYK model provides an uncommon example of a theory where Eigenstate Thermalization Hypothesis (ETH) can be verified in analytically. In this talk I will discuss this model in the deep infrared limit where the theory has an emergent conformal (reparametrization) symmetry that is broken both spontaneously and explicitly. To study the validity of ETH, we compute the heavy- light correlation functions of operators in the conformal spectrum of the theory. We compute these correlation functions with and without the contribution of the low energy (Schwarzian) modes, which are known to be the origin of the chaotic behaviour in this theory. In considering the contributions of the Schwarzian modes we find a weaker form of ETH: while the heavy operator insertions increase the effective temperature perceived by the light insertions, this effective temperature is proportional to the background temperature and goes to zero with the background temperature. In the case where Schwarzian modes aren’t considered, we find ETH in limit in which the weight of the heavy operators approach infinity. I will also discuss implications of these results for the states in AdS2 gravity dual.

The last few years have seen an explosion in our understanding of dualities in 2+1 dimensional quantum field theories. More and more examples are being uncovered, but a systematic understanding of the patterns is still missing. In this talk I will discuss how to use holography to generate large new classes of purely field theoretic dualities including generalizations of the well-studied particle/vortex duality.

Host: Pranjal Nayak

The SYK model provides an uncommon example of a theory where Eigenstate Thermalization Hypothesis (ETH) can be verified in analytically. In this talk I will discuss this model in the deep infrared limit where the theory has an emergent conformal (reparametrization) symmetry that is broken both spontaneously and explicitly. To study the validity of ETH, we compute the heavy- light correlation functions of operators in the conformal spectrum of the theory. We compute these correlation functions with and without the contribution of the low energy (Schwarzian) modes, which are known to be the origin of the chaotic behaviour in this theory. In considering the contributions of the Schwarzian modes we find a weaker form of ETH: while the heavy operator insertions increase the effective temperature perceived by the light insertions, this effective temperature is proportional to the background temperature and goes to zero with the background temperature. In the case where Schwarzian modes aren’t considered, we find ETH in limit in which the weight of the heavy operators approach infinity. I will also discuss implications of these results for the states in AdS2 gravity dual.

Description: The axion is a proposed particle whose existence might account for much of the dark matter of the universe. This same particle also arises as the solution to the strong-CP problem of particle physics. There have been several decades of experiments that have attempted to detect new particles with many of the properties of the axion - but without being sensitive to the preferred region of parameter space. I will report on the Axion Dark Matter Experiment, ADMX, which is currently running and is achieving the required sensitivity towards potential discovery. There are also new ideas in case nature has a related but different elusive solution to the dark matter problem - these will also be described with a focus on having discovery potential.

Host: Susan Gardner

I will discuss the definition and use of gravitational Wilson lines as a means of understanding the AdS/CFT dictionary. Applications will include the gravitational self-energy of point particles, and the late time behavior of Lorentzian correlators.

Host: Pranjal Nayak

Title: Gauss Bonnet Gravity and Singularity Crossing

Abstract: 

We study the effect of adding a Gauss Bonnet term to general relativity, in five dimensions, on modifying the singular behavior of certain gravitational solutions. These solutions are the Gauss Bonnet FRW cosmology and spherically symmetric Black hole solution. In these cases, we were able to show that nonspacelike geodesics can be extended across the singularities, which render these spacetimes geodesically complete. We check the consistency of these extensions with the field equations against the known Gauss Bonnet junction conditions.

Title: The Schwarzian and black hole physics

Abstract: In this talk, I will discuss the Schwarzian theory (relevant for low-energy SYK physics and Jackiw-Teitelboim gravity) from a 2d perspective. I will demonstrate how Schwarzian quantum mechanics is naturally embedded in 2d Liouville CFT. This perspective allows a direct computation of Schwarzian two- and four-point functions. Out-of-time ordered (OTO) four-point functions are also determined using the 2d R-matrix. The semi-classical limit of these expressions demonstrate various aspects of black holes, such as quasi-normal modes and eikonal shockwave expressions in the holographic bulk. In the end, I briefly discuss some generalizations to other theories. Mostly based on arXiv:1705.08408.