The Intrinsic Coupling in Integrable Quantum Field Theories

TL;DR

This paper presents a non-perturbative method to compute the intrinsic 4-point coupling in integrable quantum field theories using form factors, validated through models like Ising and O(3) sigma-models.

Contribution

It introduces a high-accuracy technique for calculating the intrinsic coupling directly from form factors in integrable QFTs, bypassing perturbative methods.

Findings

Accurate computation of intrinsic coupling in integrable QFTs.

Validation of the method with models like Ising and O(3) sigma-models.

Comparison with lattice simulations shows strong agreement.

Abstract

The intrinsic 4-point coupling, defined in terms of a truncated 4-point function at zero momentum, provides a well-established measure for the interaction strength of a QFT. We show that this coupling can be computed non-perturbatively and to high accuracy from the form factors of an (integrable) QFT. The technique is illustrated and tested with the Ising model, the XY-model and the O(3) nonlinear sigma-model. The results are compared to those from high precision lattice simulations.