Why are fractional charges of orientifolds compatible with Dirac quantization?

Yuji Tachikawa, Kazuya Yonekura

Research output: Contribution to journalArticlepeer-review

23 Citations (Scopus)


Orientifold p-planes with p ≤ 4 have fractional Dp-charges, and therefore appear inconsistent with Dirac quantization with respect to D(6−p)-branes. We explain in detail how this issue is resolved by taking into account the anomaly of the worldvolume fermions using the η invariants. We also point out relationships to the classification of interacting fermionic symmetry protected topological phases. In an appendix, we point out that the duality group of type IIB string theory is the pin+ version of the double cover of GL(2, Z).

Original languageEnglish
Article number058
JournalSciPost Physics
Issue number5
Publication statusPublished - 2019 Nov
Externally publishedYes

ASJC Scopus subject areas

  • Physics and Astronomy(all)


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