The three-boson bound state in the massive Schwinger model

TL;DR

This paper develops Feynman rules for the massive Schwinger model with a non-zero vacuum angle, analyzes the three-boson bound state, and computes its mass and decay widths using mass perturbation theory.

Contribution

It introduces matrix-valued Feynman rules for the model and provides a partial resummation to determine properties of the three-boson bound state.

Findings

Derived Feynman rules for non-zero theta

Computed the mass of the three-boson bound state

Estimated partial decay widths of the bound state

Abstract

We derive the (matrix-valued) Feynman rules of mass perturbation theory of the massive Schwinger model for non-zero vacuum angle theta. Further, we discuss the properties of the three-boson bound state and compute -- by a partial resummation of the mass perturbation series -- its mass and its partial decay widths.