Form factors of descendant operators in the massive Lee-Yang model

TL;DR

This paper computes form factors of descendant operators in the massive Lee-Yang model up to level 7, demonstrating their consistency with the $S$-matrix and conformal structure using integrability and bootstrap methods.

Contribution

It provides a systematic method to determine descendant form factors in an integrable quantum field theory up to a certain level, linking conserved quantities and bootstrap results.

Findings

Form factors of descendants are computed up to level 7.

Operator space matches conformal and bootstrap predictions.

Solutions satisfy asymptotic conditions related to operator level.

Abstract

The form factors of the descendant operators in the massive Lee-Yang model are determined up to level 7. This is first done by exploiting the conserved quantities of the integrable theory to generate the solutions for the descendants starting from the lowest non-trivial solutions in each operator family. We then show that the operator space generated in this way, which is isomorphic to the conformal one, coincides, level by level, with that implied by the $S$-matrix through the form factor bootstrap. The solutions we determine satisfy asymptotic conditions carrying the information about the level that we conjecture to hold for all the operators of the model.