D-branes in Gepner models and supersymmetry

TL;DR

This paper analyzes boundary states for D-branes in Gepner models, clarifying their supersymmetry properties, geometric interpretation, and symmetry actions, and applies these to compute instanton effects in N=2 theories.

Contribution

It provides a detailed analysis of boundary states for D-branes in Gepner models, including supersymmetry, geometry, and symmetry actions, with applications to instanton corrections.

Findings

Boundary states for D-branes are constructed and analyzed.

Supersymmetry charges are identified and their breaking patterns are clarified.

Instanton-induced corrections to hypermultiplet metrics are computed.

Abstract

Boundary states corresponding to wrapped D-branes in Calabi-Yau compactifications of type II strings are discussed using Gepner models. In particular boundary conditions corresponding to D-0 branes and D-instantons in four dimensions are investigated. The boundary states constructed by Recknagel and Schomerus are analyzed in the light-cone gauge and the broken and conserved space-time supersymmetry charges are found. The geometrical interpretation of these algebraically constructed boundary states is clarified in some simple cases. Moreover, the action of mirror symmetry and other discrete symmetries of the Gepner model on the boundary states are discussed. As an application the boundary states are used to calculate instanton induced corrections to metric on the hypermultiplets in the N=2 effective action.