### Abstract

In the presence of background Neveu-Schwarz flux, the description of the Ramond-Ramond fields of type IIB string theory using twisted K-theory is not compatible with S-duality. We argue that other possible variants of twisted K-theory would still not resolve this issue. We propose instead a connection of S-duality with elliptic cohomology, and a possible T-duality relation of this to a previous proposal for IIA theory, and higher-dimensional limits. In the process, we obtain some other results which may be interesting on their own. In particular, we prove a conjecture of Witten that the 11-dimensional spin cobordism group vanishes on K (ℤ, 6), which eliminates a potential new θ-angle in type IIB string theory.

Original language | English (US) |
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Pages (from-to) | 639-664 |

Number of pages | 26 |

Journal | Nuclear Physics B |

Volume | 715 |

Issue number | 3 |

DOIs | |

State | Published - May 30 2005 |

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### ASJC Scopus subject areas

- Nuclear and High Energy Physics

### Cite this

*Nuclear Physics B*,

*715*(3), 639-664. https://doi.org/10.1016/j.nuclphysb.2005.02.016