EPSRC-SFI: "CFT and Gravity: Heavy States and Black Holes"

Quantum Field Theory (QFT) is the common language of theoretical physics to describe quantum systems with a vast range of applications from mathematical physics to phenomenology. When the interaction among the quanta of the theory is weak it is possible to use standard techniques to obtain quantitative predictions. However, many important physical phenomena (such as e.g. superconductivity at relatively high temperatures, behavior of strongly coupled plasma, etc.) depend critically on strong interactions and so the traditional approach fails. In this project we will develop the mathematical machinery necessary to describe heavy states in quantum systems with strong interactions and apply it to the study of thermalization in quantum system and black holes in gravitational theories. These two seemingly very different problems are related in a very concrete way by gravitational holography, which relates non-gravitational quantum systems with strong interactions and higher dimensional theories of gravity.

We will use our results to provide a precise description of certain microscopic properties of black holes, which will shed new light on the black holes dynamics. We will focus on specific quantities, such as the phase shift of a wave propagating in the gravitational backgrounds which correspond to heavy states. We will study gravitational finite size effects and use this information to derive, by using quantum techniques, new classical results relevant to gravitational binaries (two black holes orbiting each other).

This project will also study thermalization in quantum systems. Imagine throwing a very heavy object into an empty box. Is this object going to dissipate into a gas of light particles (thermalize) and fill the available volume or will it just keep floating around? Does the fate of the heavy object depend on the strength of interactions between the matter constituents? In the holographic description the question can be reformulated - does a heavy object behave like a black hole? We will investigate these questions with a combination of quantum consistency conditions, holography and more traditional methods involving Feynman diagrams. The goal is to understand whether all quantum systems with a large number of species of particles thermalize. If true, this would imply that different quantum systems resemble each other much more closely than previously thought. We will also search for new symmetries which underline the behavior of certain observables in quantum field theories.