K-theory and Ramond-Ramond charge

TL;DR

This paper explores how the topology of Chan-Paton bundles determines the Ramond-Ramond charge of D-branes, linking topological invariants to physical charge in string theory.

Contribution

It demonstrates that nontrivial normal bundles induce RR charge, supporting the view that D-brane charge is classified by K-theory.

Findings

Normal bundle topology induces RR charge

D-brane charge corresponds to K-theory elements

Topological features determine physical charge

Abstract

We discuss the relation between the Ramond-Ramond charges of D-branes and the topology of Chan-Paton vector bundles. We show that a topologically nontrivial normal bundle induces RR charge and that the result fits in perfectly with the proposal that D-brane charge is the topology of the Chan-Paton bundle, regarded as an element of K-theory.