Form factors and generalized hydrodynamics for integrable systems

TL;DR

This paper reviews the microscopic foundations of generalized hydrodynamics (GHD) in integrable systems, developing form factor expansions for ground states and GGEs, and comparing these with GHD predictions.

Contribution

It introduces form factor expansions for GGE states and compares these with GHD, providing a deeper microscopic understanding of GHD in integrable systems.

Findings

Form factor expansions match GHD predictions for GGE states.

GGE averaged microscopic currents can be derived via form factors.

A second approach based on self-conserved currents is discussed.

Abstract

Our review covers microscopic foundations of generalized hydrodynamics (GHD). As one generic approach we develop form factor expansions, for ground states and generalized Gibbs ensembles (GGE). In the latter case the so obtained results are compared with predictions from GHD. One cornerstone of GHD are the GGE averaged microscopic currents, which can also be obtained through employing form factors. Discussed is a second, completely orthogonal approach based on the availability of a self-conserved current.