## Abstract

We demonstrate that twisted equivariant differential K-theory of transverse complex curves accommodates exotic charges of the form expected of codimension =2 defect branes, such as of D7-branes in IIB/F-theory on -type orbifold singularities, but also of their dual 3-brane defects of class-S theories on M5-branes. These branes have been argued, within F-theory and the AGT correspondence, to carry special SL(2)-monodromy charges not seen for other branes, at least partially reflected in conformal blocks of the 2-WZW model over their transverse punctured complex curve. Indeed, it has been argued that all "exotic"branes of string theory are defect branes carrying such U-duality monodromy charges - but none of these had previously been identified in the expected brane charge quantization law given by K-theory. Here we observe that it is the subtle (and previously somewhat neglected) twisting of equivariant K-theory by flat complex line bundles appearing inside orbi-singularities ("inner local systems") that makes the secondary Chern character on a punctured plane inside an -type singularity evaluate to the twisted holomorphic de Rham cohomology which Feigin, Schechtman and Varchenko showed realizes 2k-conformal blocks, here in degree 1 - in fact it gives the direct sum of these over all admissible fractional levels k = -2 + κ/r. The remaining higher-degree 2k-conformal blocks appear similarly if we assume our previously discussed "Hypothesis H"about brane charge quantization in M-theory. Since conformal blocks - and hence these twisted equivariant secondary Chern characters - solve the Knizhnik-Zamolodchikov equation and thus constitute representations of the braid group of motions of defect branes inside their transverse space, this provides a concrete first-principles realization of anyon statistics of - and hence of topological quantum computation on - defect branes in string/M-theory.

Original language | English (US) |
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Article number | 2350009 |

Journal | Reviews in Mathematical Physics |

Volume | 35 |

Issue number | 6 |

DOIs | |

State | Published - Jul 1 2023 |

## Keywords

- K-theory
- String theory
- algebraic topology
- branes
- conformal field theory

## ASJC Scopus subject areas

- Statistical and Nonlinear Physics
- Mathematical Physics