The unreasonable effectiveness of the large charge expansion (東京)

Abstract

We compute conformal dimensions and other physical quantities for strongly coupled conformal field theories in three dimensions with global symmetries. We show how in sectors of large global charge $Q$, the charge acts as a controlling parameter and physical quantities can be explicitly computed in a $1/Q$ perturbative expansion. In the case of the $O(2)$ model we show how the predictions of this approach are in very good agreement with lattice measurements.