String Theory seminar - Christopher Rosen Seminar

In 2+1 dimensional field theories, a well known "particle-vortex" duality rephrases a system with a gauged U(1) in terms of "magnetic" variables that can be more convenient for performing calculations. These magnetic variables have historically proven useful for understanding the possible phases available to interacting matter at finite density, which is a problem of great interest across many fields of physics.

By virtue of the AdS/CFT correspondence, the ABJM theory provides an excellent testing ground for the physics of strongly interacting matter at finite density in three dimensions. There too operators carrying magnetic flux arise, and it is natural to wonder how this "composite" matter behaves when placed at finite density. Holographically, we investigate this question by studying the fermion spectral function for composite fermions in the ABJM theory by solving the Dirac equation for linearized fermionic fluctuations around particular solutions of N=8 maximal gauged supergravity in four dimensions. The backgrounds of interest correspond to zero temperature phases in which the monopole number density has been broken, and are examples of holographic RG flows. We find that these candidate ground states appear to support Fermi surfaces of composite fermions, and that the low energy fermionic fluctuations around these Fermi surfaces are perfectly stable within a particular kinematic window. In addition to an explicit identification of the participating field theory operators, the model's top-down pedigree also allows for some basic information about the stability of these states at low temperatures.