Boundary sine-Gordon model

TL;DR

This paper reviews recent advances in understanding the boundary sine-Gordon model, including spectrum determination, reflection factors, and the relation between boundary resonances and classical instabilities, validated through multiple methods.

Contribution

It provides a comprehensive on-shell description of the boundary sine-Gordon model, including boundary state spectrum, reflection factors, and their validation methods.

Findings

Boundary state spectrum determined via boundary bootstrap

Reflection factors computed and validated

Boundary resonance linked to classical instability

Abstract

We review our recent results on the on-shell description of sine-Gordon model with integrable boundary conditions. We determined the spectrum of boundary states together with their reflection factors by closing the boundary bootstrap and checked these results against WKB quantization and numerical finite volume spectra obtained from the truncated conformal space approach. The relation between a boundary resonance state and the semiclassical instability of a static classical solution is analyzed in detail.