November 14: “A holographic effective field theory for a metal with a Fermi surface” by Dominic Else

Accessing the physics of strongly coupled metals in a controlled way is a challenging problem in theoretical condensed matter physics. In this talk, I will re-examine the possibility of understanding strongly coupled metals through a holographic dual. A core requirement in for any physically reasonable model of a metal is the existence of a Fermi surface in momentum space where the low-energy excitations live, satisfying “Luttinger’s theorem” which relates its volume to the microscopic charge density. In many holographic modes of metals, such a Fermi surface is not apparent in the classical limit of the holographic bulk theory; it may come back from quantum effects in the bulk, but exactly how this occurs has not been fully explored. By contrast, in this talk I will discuss a new approach in which the Fermi surface is explicitly built in. The idea is that for applications, it should be sufficient to construct a holographic dual of the effective field theory that controls the infra-red physics of the metal. I then invoke recent work that has identified a precise criterion for such an effective field theory to be “emergeable” from a continuum UV theory at nonzero charge density. I show that imposing this criterion leads to a holographic model of a strongly coupled metal with the Fermi surface built in, leading to a seemingly physically reasonable model of a strongly coupled metal.