Triangle Seminars

Abstract:
In this talk I will discuss superconformal theories in four
dimensions obtained wrapping M5 branes on a Riemann surface. I will
first review N=2 class S theories introduced some years ago by Gaiotto
and then describe a generalization to the N=1 case. For this class of
theories it is possible to write down a spectral curve encoding the
properties of the chiral ring and I propose a method to determine from
the spectral curve the scaling dimension of chiral operators in the
SCFT. This proposal reduces to the correct prescription in the special
case of N=2 theories. I will provide several consistency checks and
apply this method to study some new superconformal theories.

Abstract:
I discuss general properties of supersymmetric Anti-de Sitter (AdS) backgrounds, in particular regarding their moduli spaces and domain walls. I argue that lower-dimensional gauged supergravity is a strong tool to understand supersymmetric AdS backgrounds, independent of the compactification manifold. I show how the moduli space can be determined and explain what this means for the dual conformal field theories. In the last part I comment on supersymmetric domain walls and their dual interpretation as supersymmetric RG- flows.

Abstract:
I will discuss what we have learned in the past year about transport in strongly interacting metallic phases by studying the linear response of planar black holes with broken translational symmetry. Firstly, I will discuss how holography tells us that the conductivity of weakly disordered metals is described by the Drude formula, confirming a "prediction" of the many-body memory matrix approach. Secondly, I will discuss the derivation of non-perturbative conductivity bounds, invoking a new version of the holographic membrane paradigm. These bounds rule out disorder-driven phase transitions (which would generically exist in traditional condensed matter models) in the boundary theory under rather mild assumptions about the existence and nature of solutions to Einstein's equations. Connections between these black-hole inspired theories of transport and novel experiments in graphene will also be discussed.

Abstract:
I will review some recent progress about superconformal field theories in six dimensions. A simple class has an effective description in terms of a chain of gauge fields, coupled by tensors and hypermultiplets. Their holographic duals are now known analytically, and some precision checks can be performed, involving Weyl anomalies. An extension of this class can be studied using F-theory.
All these theories have some features in common with the elusive theory describing M5-branes, and indeed suggest new phenomena, such as M5 fractionation.

Abstract:
I will present several new 3d N=2 dualities with super-potentials involving monopole operators. Some of the theories that I will discuss describe systems of D3 branes ending on pq-webs. In these cases 3d mirror symmetry is a consequence of S-duality.