Universal Features of the Excitation Spectrum in Generalized Gibbs Distribution Ensemble

TL;DR

This paper demonstrates that the excitation spectra of Generalized Gibbs Ensembles in 1D integrable models exhibit universal features, especially in the low-energy isotopic excitations, which resemble ferromagnetic behavior under certain conditions.

Contribution

It reveals universal properties of excitation spectra in GGE for 1D integrable models, linking low-energy isotopic excitations to ferromagnetic effective actions.

Findings

Low energy isotopic excitations follow a ferromagnet effective action.

Universality holds when entropy per excited particle is small.

Spectral features are insensitive to distribution details.

Abstract

It is shown that excitation spectra of Generalized Gibbs Ensembles (GGE) of one-dimensional integrable models with isotopic symmetry contain universal features insensitive to details of the distribution. Namely, the low energy limit of the subsystem of isotopic (for instance, spin) excitations is described by the effective action of a ferromagnet at thermodynamic equilibrium with a single temperature and with the stiffness determined by the initial conditions. The condition of universality is that the entropy per excited particle is small.