Boundary states in coset conformal field theories

TL;DR

This paper constructs boundary states in coset conformal field theories, including twisted states, by relating them to boundary states of the constituent theories, with applications to su(n) and parafermion models.

Contribution

It introduces a method to build twisted boundary states in G/H theories from those of G and H, using brane identification and selection rules.

Findings

Constructed twisted boundary states for G/H theories.

Applied method to su(n) diagonal cosets.

Derived boundary states for su(2)/u(1) parafermion theory.

Abstract

We construct various boundary states in the coset conformal field theory G/H. The G/H theory admits the twisted boundary condition if the G theory has an outer automorphism of the horizontal subalgebra that induces an automorphism of the H theory. By introducing the notion of the brane identification and the brane selection rule, we show that the twisted boundary states of the G/H theory can be constructed from those of the G and the H theories. We apply our construction to the su(n) diagonal cosets and the su(2)/u(1) parafermion theory to obtain the twisted boundary states of these theories.