On entanglement entropy in 't Hooft model

Abstract

We use the replica trick approach to calculate, in the large-N limit, the entanglement c-function in two-dimensional quantum chromodynamics with the gauge group U(N) and quark in the fundamental representation ('t Hooft model). We show explicitly that the result is equal to a sum (with certain numerical coefficients) of entanglement c-functions of free massive scalars, which represent mesons in spectrum of the 't Hooft model. Interestingly, each meson contributes as a point-like particle. We provide an explanation for why this is the case.