New instanton effects in string theory

Chris Beasley, Edward Witten

Research output: Contribution to journalArticlepeer-review

66 Scopus citations


We describe a new class of instanton effects in string compactifications that preserve only N ≤ 1 supersymmetry in four dimensions. As is well-known, worldsheet or brane instantons in such a background can sometimes contribute to an effective superpotential for the moduli of the compactification. We generalize this phenomenon by showing that such instantons can also contribute to new multi-fermion and higher-derivative F-terms in the low-energy effective action. We consider in most detail the example of heterotic compactification on a Calabi-Yau threefold X with gauge bundle V, in which case we study worldsheet instanton effects that deform the complex structure of the moduli space associated to X and V. We also give new, slightly more economical derivations of some previous results about worldsheet instantons in Type IIA Calabi-Yau compactifications.

Original languageEnglish (US)
Pages (from-to)60
Number of pages1
JournalJournal of High Energy Physics
Issue number2
StatePublished - Feb 1 2006
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics


  • Solitons Monopoles and Instantons
  • Superstrings and Heterotic Strings
  • Topological Strings


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