I will review a few recent papers on 4d, N=3 superconformal field theories.

We develop an effective field theory for dissipative fluids which governs the dynamics of long-lived gapless modes associated with conserved quantities. The resulting theory gives an action formulation of fluctuating hydrodynamics which incorporates systematically nonlinear interactions of noises. The theory applies to nonlinear disturbances…

Soft theorems for the scattering of low energy photons and gravitons and cosmological consistency relations on the squeezed-limit correlation functions are both understood to be consequences of invariance under large gauge transformations. I will show how one can apply the same method used in cosmology – based on the identification of an infinite…

I'll review a few recent papers that discuss the subject in the title, focusing on results based on AdS/CFT.

We present a method in 2d CFT for calculating correlators in a state corresponding to the spherical collapse of a shell of matter in three dimensional quantum gravity. In field theory terms, we describe the equilibration process, from early times to thermalization, of a CFT following a sudden injection of energy at time t = 0. Our approach is a…

“Bubbles of nothing” are a dramatic instability of spacetimes with compact extra dimensions. A hole appears in spacetime, inside of which there is neither space nor time: there is literally “nothing”. Witten showed that they may nucleate by quantum tunneling. I will discuss bubbles of nothing that nucleate instead by thermal fluctuation (or by a…

I will discuss determinant formulas for higher-dimensional CFTs, which was known in the 70's but extended to SCFTs only recently. I will discuss the implications of the formula for the discussion of unitarity bounds and for the analytic structures of conformal blocks.

The extremal gravity proposal is a conjectured duality between pure gravity in three dimensions and a speculative set of 2d CFTS. I will discuss a computation of the number of black hole micro-states in these theories. This micro-state counting inspires a mild modification of the extremal gravity proposal which passes many non-trivial checks, and…

One can easily be frustrated by the tremendous redundancy in possible physical description. By this I mean the freedom to choose gauge, make field redefinitions, add any amount of auxiliary spectator matter, and the such. Happily we can exploit such freedom to encourage the emergence of a new duality in gauge theories. The existence of a duality…

The 4d superconformal index is a partition function (somewhat analogous to the quantum mechanical Witten index, or the 2d SCFT elliptic genus) that counts supersymmetric operators in 4d superconformal field theories. As a partition function it depends on a ``temperature'' parameter which enters the Boltzmann weights of various operators. I will…

This talk will describe recent work on the classification of elliptic Calabi-Yau threefolds and fourfolds, and consequences for the physics of supersymmetric F-theory vacua. The mathematical theory of minimal surfaces and the physically-motivated notion of "non-Higgsable clusters" provide tools that enable the systematic classification and…

N=8 supergravity is not renormalizable. This means the presense of power divergences in the amplitudes. There are also logarithmic divergences that multiply higher-dimensional counterterms. In all probability, the latter appear starting from the 7-th or maybe from the 8-th loop. Supergravity is extremely complicated, and it makes sense to…

In this talk I will explore the constraints imposed by conformal invariance on defects in a conformal field theory. Correlation function of a conformal defect with a bulk local operator is fixed by conformal invariance up to an overall constant. This gives rise to the notion of defect expansion, where the defect itself is expanded in terms of…

"The SU(N)_1 WZW model is constructed on a n-sheeted branched torus, which allows for the investigation of the Renyi entropy for a single interval at finite temperature . Issues relevant for bose-fermi equivalence and Renyi entropy for theories with gauge fields will be discussed"

A global quench is an interesting setting where we can study thermalization of subsystems in a pure state. We investigate the spread of entanglement following a global quench in holography, toy models, and free field theory. In particular, we focus on two speeds: the tsunami velocity determining the linear growth of entanglement entropy at early…

Abstract: The replica trick plays an important role in several considerations of condensed matter physics and statistical physics. Recently, it has also played a role in several contexts in high energy theory and holography. We discuss some of the features that occur when the replica symmetry is broken, using a simple spin glass toy model from…

There is an interesting duality in (2+1)d between theories of interacting bosons and U(1) gauge theories with bosonic charge, also known as charge-vortex duality. This duality is very useful for theoretically accessing various strongly interacting phases of matter, which I will briefly describe. More recently, a similar duality between Dirac…

Abstract: Engineering quantum field theories in String Theory in terms of branes is a powerful approach for understanding their dynamics. In this talk, I will present recent progress in the realization of 2d N=(0,2) gauge theories in terms of branes. I will discuss Brane Brick Models, a novel type of Type IIA brane configurations consisting of D4…