Boundary states and finite size effects in sine-Gordon model with Neumann boundary condition

TL;DR

This paper studies the sine-Gordon model with Neumann boundary conditions, analyzing boundary bound states, finite size effects, and confirming theoretical predictions through numerical methods.

Contribution

It develops a framework for finite size effects in boundary integrable theories and confirms boundary bound states and reflection factors using the truncated conformal space approach.

Findings

Boundary bound states spectrum established

Coexistence of Coleman-Thun diagrams and bound state creation found

Finite size effects framework validated with numerical methods

Abstract

The sine-Gordon model with Neumann boundary condition is investigated. Using the bootstrap principle the spectrum of boundary bound states is established. Somewhat surprisingly it is found that Coleman-Thun diagrams and bound state creation may coexist. A framework to describe finite size effects in boundary integrable theories is developed and used together with the truncated conformal space approach to confirm the bound states and reflection factors derived by bootstrap.