简介: |
We describe the large N saddle point, and the structure
of fluctuations about the saddle point, of a theory containing a
sharp, critical Fermi surface in twospatial dimensions. The theory
describes the onset of Ising order in a Fermi liquid, and closely
related theories apply to other cases with critical Fermi surfaces.
Inspired by SYK models, we employ random couplings in flavorspace
between the fermions and the bosonic order parameter, but there is
no spatial randomness: consequently, the G-Σ path integral of the
theory is expressed in terms of fields bilocal in spacetime. We show
by transport calculations that this first theory realizes a
non-Fermi liquid but not a strange metal due to various
cancellations related to momentum conservation. Next, we consider a
theory with spatiallyrandom disorder, and demonstratethat it
realizes a marginal Fermi liquid but not a strange metal. Finally,
we propose that a strange metal can be realized by a theory with
spatially random Yukawa interactions. |