Mass Generation in Perturbed Massless Integrable Models

TL;DR

This paper extends form-factor perturbation theory to non-integrable deformations of massless integrable models, providing a new approach to analyze mass generation and confinement phenomena more effectively than traditional renormalization group methods.

Contribution

It introduces a novel extension of form-factor perturbation theory applicable to non-integrable massless models, enabling detailed analysis of mass gaps and confinement at first order.

Findings

Identification of operators responsible for mass gap creation

Detection of confinement of massless particles

Enhanced understanding of non-integrable perturbations

Abstract

We extend form-factor perturbation theory to non--integrable deformations of massless integrable models, in order to address the problem of mass generation in such systems. With respect to the standard renormalisation group analysis this approach is more suitable for studying the particle content of the perturbed theory. Analogously to the massive case, interesting information can be obtained already at first order, such as the identification of the operators which create a mass gap and those which induce the confinement of the massless particles in the perturbed theory.