Please note that the list below only shows forthcoming events, which may not include regular events that have not yet been entered for the forthcoming term. Please see the past events page for a list of all seminar series that the department has on offer.

 

Past events in this series


Tue, 30 Apr 2024
13:00
L2

Determinants in self-dual N = 4 SYM and twistor space

Frank Coronado
(McGill)
Abstract
Self-dual Yang-Mills famously have a description in terms of twistors; one of the outstanding questions is how to promote it to full (non-self-dual) Yang-Mills and learn about its dynamics. In this talk, I will present some progress in this direction in the "most symmetric" Yang-Mills theory; namely N=4 super Yang-Mills in four dimensions. I will express the full Yang-Mills theory as a deformation of self-dual Yang-Mills. By treating the deformation perturbatively and using the formalism of twistors, I will write down the loop-integrands of correlation functions of determinant operators in the planar limit at any order in the 't Hooft coupling. Interestingly, the final expression is given by a partition function of a "dual" matrix model. This in turn manifests a ten-dimensional structure that combines spacetime and R-charge symmetries of SYM.
 


 

Tue, 28 May 2024
13:00
L2

Disordered quantum critical fixed points from holography

Andrew Lucas
(Boulder )
Abstract

In this talk I will describe the systematic construction of strongly interacting RG fixed points with a finite disorder strength.  Such random-field disorder is quite common in condensed matter experiment, necessitating an understanding of the effects of this disorder on the properties of such fixed points. In the past, such disordered fixed points were accessed using e.g. epsilon expansions in perturbative quantum field theory, using the replica method to treat disorder.  I will show that holography gives an alternative picture for RG flows towards disordered fixed points.  In holography, spatially inhomogeneous disorder corresponds to inhomogeneous boundary conditions for an asymptotically-AdS spacetime, and the RG flow of the disorder strength is captured by the solution to the Einstein-matter equations. Using this construction, we have found analytically-controlled RG fixed points with a finite disorder strength.  Our construction accounts for, and explains, subtle non-perturbative geometric effects that had previously been missed.  Our predictions are consistent with conformal perturbation theory when studying disordered holographic CFTs, but the method generalizes and gives new models of disordered metallic quantum criticality.