Breather boundary form factors in sine-Gordon theory

TL;DR

This paper tests conjectured exact form factors of boundary exponential operators in sine-Gordon theory against numerical data, confirming their validity overall but noting unresolved discrepancies in diagonal matrix elements.

Contribution

It provides the first numerical validation of conjectured boundary form factors in sine-Gordon theory, highlighting both successes and unresolved issues.

Findings

Numerical data strongly support the conjectured form factors.

Discrepancies observed in diagonal matrix elements.

Results reinforce the validity of boundary form factors in sine-Gordon theory.

Abstract

A previously conjectured set of exact form factors of boundary exponential operators in the sinh-Gordon model is tested against numerical results from boundary truncated conformal space approach in boundary sine-Gordon theory, related by analytic continuation to sinh-Gordon model. We find that the numerical data strongly support the validity of the form factors themselves; however, we also report a discrepancy in the case of diagonal matrix elements, which remains unresolved for the time being.