Exact two-particle Matrix Elements in S-Matrix Preserving Deformation of Integrable QFTs

TL;DR

This paper derives explicit two-particle form factors in integrable quantum field theories under S-matrix preserving deformations related to Unruh temperature variations, revealing a unified pattern using Barnes' functions.

Contribution

It provides explicit formulas for deformed two-particle form factors across multiple integrable models, advancing the understanding of their thermal response.

Findings

Explicit two-particle form factors for various models

Unified pattern using Barnes' multi-periodic functions

Connection between S-matrix deformation and form factors

Abstract

In a recent paper it was shown that the response of an integrable QFT under variation of the Unruh temperature can be computed from a S-matrix preserving deformation of the form factor approach. We give explicit expressions for the deformed two-particle formfactors for various integrable models: The Sine-Gordon and SU(2) Thirring model, several perturbed minimal CFTs and the real coupling affine Toda series. A uniform pattern is found to emerge when both the S-matrix and the deformed form factors are expressed in terms Barnes' multi-periodic functions.