Projections in string theory and boundary states for Gepner models

TL;DR

This paper investigates how supersymmetry-preserving projections in string theory affect boundary states in Gepner models, emphasizing the importance of fixed point resolution and model-independent consistency conditions.

Contribution

It provides a model-independent analysis of boundary conditions and fixed point resolutions in Gepner models, ensuring supersymmetry and integrality of annulus coefficients.

Findings

Proper boundary conditions preserve supersymmetry.

Fixed point resolution is crucial for boundary state consistency.

Annulus coefficients are guaranteed to be integral by model-independent arguments.

Abstract

In string theory various projections have to be imposed to ensure supersymmetry. We study the consequences of these projections in the presence of world sheet boundaries. A-type boundary conditions come in several classes; only boundary fields that do not change the class preserve supersymmetry. Our analysis takes in particular properly into account the resolution of fixed points under the projections. Thus e.g. the compositeness of some previously considered boundary states of Gepner models follows from chiral properties of the projections. Our arguments are model independent; in particular, integrality of all annulus coefficients is ensured by model independent arguments.