## Abstract

We reconsider the question of which Calabi-Yau compactifications of the heterotic string are stable under world-sheet instanton corrections to the effective space-time superpotential. For instance, compactifications described by (0,2) linear sigma models are believed to be stable, suggesting a remarkable cancellation among the instanton effects in these theories. Here, we show that this cancellation follows directly from a residue theorem, whose proof relies only upon the right-moving world-sheet supersymmetries and suitable compactness properties of the (0,2) linear sigma model. Our residue theorem also extends to a new class of "half-linear" sigma models. Using these half-linear models, we show that heterotic compactifications on the quintic hypersurface in CP^{4} for which the gauge bundle pulls back from a bundle on CP ^{4} are stable. Finally, we apply similar ideas to compute the superpotential contributions from families of membrane instantons in M-theory compactifications on manifolds of G_{2} holonomy.

Original language | English (US) |
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Pages (from-to) | 1703-1741 |

Number of pages | 39 |

Journal | Journal of High Energy Physics |

Volume | 7 |

Issue number | 10 |

DOIs | |

State | Published - Oct 1 2003 |

Externally published | Yes |

## All Science Journal Classification (ASJC) codes

- Nuclear and High Energy Physics

## Keywords

- M-Theory
- Solitons Monopoles and Instantons
- Superstrings and Heterotic Strings