Search Talks

 In this talk, I will describe recent work on holographic correspondences in spacetimes which interpolate from anti-de Sitter space in the deep bulk to asymptotic regions which share some properties with flat space. Examples include the linear dilaton throat in the F1-NS5 solution and the NCOS decoupling limit of the D1-D5 system. In both examples, null geodesics take infinite coordinate time to reach the boundary, the causal structure resembles that of Minkowski space, and we can sensibly study radiation near future null infinity. These spacetimes are good solutions of string theory and thus might be considered candidates for a top-down sort of celestial holography.

High temperatures are typically thought to increase disorder. Here we examine this idea in Quantum Field Theory in 2+1 dimensions. For this sake we explore a novel class of tractable models, consisting of nearly-mean-field scalars interacting with critical scalars. We identify UV-complete, local, unitary models in this class and show that symmetry breaking $\mathbb{Z}_2 \to \emptyset$ occurs at any temperature in some regions of the phase diagram. This phenomenon, previously observed in models with fractional dimensions, or in the strict planar limits, or with non-local interactions, is now exhibited in a local, unitary 2+1 dimensional model with a finite number of fields.

I describe a new solution to the Higgs hierarchy problem based on a dynamical vacuum selection mechanism in a landscape which scans the Higgs mass. The Higgs potential only admits a stable minimum when its mass is less than a critical value, cosmologically crunching away patches with a heavier Higgs. This critical value is set by the instability scale where the Higgs quartic turns negative. I consider the phenomenology of two explicit models that address the hierarchy problem in this context.

In this talk I will outline a fundamentally quantum description of bosonic dark matter from which the conventional classical-wave picture emerges when the mass is far below 10 eV. Exploiting fundamental results from quantum optics I will argue that the density matrix for dark matter is explicitly mixed. The formalism provides a continuous description of DM through the wave-particle transition, and using this I show how density fluctuations over various physical scales evolve between the two limits, with a unique behavior for DM emerging near the boundary of the wave and particle descriptions. If time permits, I will briefly describe how these effects would appear in axion haloscopes.