High Energy Physics

In this talk I will discuss the non-equilibrium response of Chern insulators [1]. Focusing on the Haldane model, we study the dynamics induced by quantum quenches between topological and non-topological phases. A notable feature is that the Chern number, calculated for an infinite system, is unchanged under the dynamics following such a quench. However, in finite geometries, the initial and final Hamiltonians are distinguished by the presence or absence of edge modes. We study the edge excitations and describe their impact on the experimentally-observable edge currents and magnetization. We show that, following a quantum quench, the edge currents relax towards new equilibrium values, and that there is light-cone spreading of the currents into the interior of the sample. I will briefly comment on a complementary project to understand non-equilibrium charge transport using gauge-gravity duality and hydrodynamics.

[1] M. D. Caio, N. R. Cooper, M. J. Bhaseen, Quantum Quenches in Chern Insulators, arXiv:1504.01910

As an experimentalist involved in the search for physics beyond the Standard Model at the LHC, one must choose carefully which signatures to pursue. While theoretical guidance in identifying well motivated gaps in the coverage of “natural” BSM extensions is an important ingredient in this choice, unexplored territory is often unexplored for a reason, namely that there are likely non-trivial (“tricky”) experimental difficulties. One must thus consider the risk (time) vs. reward (discovery) in deciding what to pursue. In this talk, I will take you through my though process as I was confronted with this optimization problem in Run 1 of the LHC, using the CMS search for disappearing tracks (sensitive to AMSB supersymmetric scenarios) as an example of what non-trivial experimental difficulties are encountered in such an analysis. I will conclude with a discussion of how my thinking on this topic has evolved for Run 2 of the LHC that has just recently begun.