Exact real-time longitudinal correlation functions of the massive XXZ chain

TL;DR

This paper presents an exact analytical method to compute real-time longitudinal spin-spin correlation functions in the antiferromagnetic XXZ chain at zero temperature, capturing all excitations without approximations.

Contribution

It introduces a thermal form factor expansion approach that provides exact, comprehensive real-time correlation functions for the XXZ chain at T=0.

Findings

Exact correlation functions for arbitrary distances and times.

All excitation types included in the analytical results.

No approximations used in the calculations.

Abstract

We apply the recently developed thermal form factor expansion method to evaluate the real-time longitudinal spin-spin correlation functions of the spin-$\frac{1}{2}$ XXZ chain in the antiferromagnetically ordered regime at temperature $T=0$. An analytical result containing all types of excitations in the model is obtained, without any approximations. This allows for the accurate calculation of the real-time correlation functions in this strongly interacting quantum system for arbitrary distances and times.