Form factors in finite volume II:disconnected terms and finite temperature correlators

TL;DR

This paper extends the study of form factors in finite volume integrable quantum field theories to include disconnected terms and finite temperature correlators, providing new computational methods and numerical verification.

Contribution

It introduces a new approach to compute disconnected form factors and finite temperature correlators, validated by numerical methods.

Findings

Validated the new method for low temperature expansion up to third order

Extended form factor analysis to include disconnected matrix elements

Provided numerical verification using truncated conformal space approach

Abstract

Continuing the investigation started in a previous work, we consider form factors of integrable quantum field theories in finite volume, extending our investigation to matrix elements with disconnected pieces. Numerical verification of our results is provided by truncated conformal space approach. Such matrix elements are important in computing finite temperature correlation functions, and we give a new method for generating a low temperature expansion, which we test for the one-point function up to third order.