1:30 pm VIA ZOOM
Large N theory of critical Fermi surfaces, Ilya Esterlis, Harvard University
I will discuss recent work on a large-N theory of critical Fermi surfaces in two dimensions. The theory applies directly to the onset of Ising order in a Fermi liquid, and is easily generalized to other forms of order. By employing random couplings in flavor-space while retaining spatial translation invariance, we find the large-N saddle point equations are the same as those appearing in other contexts; e.g., Eliashberg-like theories, and our approach therefore provides a systematic framework for assessing and going beyond such theories. I will also discuss the the large-N phase diagram of the system away from criticality, and show that the ordered side is characterized by a regime of unusually strong thermal fluctuations. Time permitting, I will also review the behavior of various fermion bilinear operators, which can be used to diagnose the instabilities of the critical Fermi surface.