Spontaneous Breaking of U(1) Symmetry in Coupled Complex Sachdev-Ye-Kitaev Models

Spontaneous Breaking of U(1) Symmetry in Coupled Complex Sachdev-Ye-Kitaev Models
Grigory Tarnopolsky, Harvard University
Grigory Tarnopolsky
Date and time: Thu, Mar 04, 2021 - 11:30am
Category: Condensed Matter Seminar
Abstract:

We study two copies of the Sachdev-Ye-Kitaev (SYK) model of N complex fermions coupled by a quartic term preserving the U (1) × U (1) symmetry. When the coupling coefficient α lies in a certain range, the large N theory is nearly conformal. We derive the large N Dyson-Schwinger equations and show that for the coupling α outside this range, the axial U(1) symmetry is spontaneously broken at low temperatures. We support these findings by exact diagonalization extrapolated to large N.