K-theoretic matching of brane charges in S- and U-duality

Abstract

We discuss K-theoretic matching of D-brane charges in the string duality between type I on T4 and type IIA on K3. This case is more complex than the familiar case of IIA/IIB duality, which is already well understood, but it turns out that replacing K3 by its orbifold blow-down seems to largely resolve the apparent problems with the theory © 2012 International Press.