Integral representations for correlation functions of the XXZ chain at finite temperature

TL;DR

This paper introduces a new integral formula for correlation functions in the finite-temperature XXZ spin chain, combining algebraic Bethe ansatz and quantum transfer matrix methods.

Contribution

It presents a novel multiple integral representation for the generating function of correlation functions at finite temperature and magnetic field.

Findings

Derived a new integral representation for correlation functions

Combined algebraic Bethe ansatz with quantum transfer matrix techniques

Provides a tool for analyzing thermodynamic properties of the XXZ chain

Abstract

We derive a novel multiple integral representation for a generating function of the $\s^z$-$\s^z$ correlation functions of the spin-$\2$ XXZ chain at finite temperature and finite, longitudinal magnetic field. Our work combines algebraic Bethe ansatz techniques for the calculation of matrix elements with the quantum transfer matrix approach to thermodynamics.