Triangle Seminars

Abstract:
After a review of the quasinormal mode method for partition function calculation developed by Denef, Hartnoll, and Sachdev, we study a scalar in AdS2. We find a series of zero modes with negative real values of the conformal dimension whose presence indicates a series of poles in the one-loop partition function. The contribution of these poles to the AdS partition function at physical mass values matches previous results. Additionally, extending our results to AdS in any even dimension 2n, we find a similar series of zero modes related to discrete series representations of SO(2n,1), and successfully calculate the one-loop determinant from these modes. Finally, we speculate on the physical meaning of these non-physical-mass modes.

Abstract:
Sleep is core to our ability to function and there is increasing evidence that poor or mis-timed sleep increases our risk of cardio vascular disease, type II diabetes, obesity and cognitive decline. In this talk I will discuss the mechanisms that are believed to underlie sleep wake regulation and review some recent mathematical models. In particular, I will focus on age-related changes to sleep and explain how the mathematical models can be used to bring insight into the possible mechanisms that could cause these changes.

Abstract:
Holography is a tool that can be most readily applied to studies of transport properties in gauge theories with infinitely strong interactions. Coupling constant corrections can then be incorporated through higher-derivative (alpha-prime) corrections to the supergravity action in the bulk. In the first part of this talk, I will discuss the dependence of higher-order hydrodynamic transport (beyond Navier-Stokes) and the higher-frequency (quasi-normal) spectrum on the coupling constant in duals of Type IIB supergravity and curvature-squared theories. In relation to the membrane paradigm, I will then present higher-order generalisations of the universal "eta over s" relation and universal anomalous conductivities at finite coupling. Recently, studies of holographic transport in the presence of broken translational symmetry and disorder have received much attention. In particular, it has been shown how thermo-electric conductivities can be computed by using the membrane paradigm. Through the power of the membrane paradigm and with a view towards future models of many-body localisation without hydrodynamic transport, in the second part of this talk, I will discuss the proofs of the lower bounds on thermal and electrical conductivities in a large family of holographic theories with arbitrarily strong disorder.

Abstract:
I will show that the matter content of the Standard Model takes a simple form
when expressed in terms of world-lines of spinning particles and set this in the context
of an effective string theory of the Standard Model described by tensionless spinning
strings with contact interactions.