## Abstract

We develop techniques to classify D- and F-flat directions for N = 1 supersymmetric string vacua of the perturbative heterotic string theory, which possess an anomalous U(1) gauge group at the tree level. Genus-one corrections generate a Fayet-Iliopoulos term for the D-term of U(1)_{A}, which is cancelled by non-zero vacuum expectation values (VEVs) of certain massless multiplets, in such a way that the anomalous U(1) is broken, while maintaining the D- and F-flatness of the effective field theory. A systematic analysis of flat directions is given for non-zero VEVs of non-Abelian singlets, and the techniques are illustrated for a specific model. The approach sets the stage to classify the D- and F-flat directions for a large class of perturbative string vacua. This classification is a prerequisite to systematically addressing the phenomenological consequences of these models.

Original language | English (US) |
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Pages (from-to) | 3-26 |

Number of pages | 24 |

Journal | Nuclear Physics B |

Volume | 525 |

Issue number | 1-2 |

DOIs | |

State | Published - Aug 10 1998 |

## All Science Journal Classification (ASJC) codes

- Nuclear and High Energy Physics

## Keywords

- Anomalous U(1)
- Flat directions
- Superstring models