Type IIB string theory, S-duality, and generalized cohomology Original Research Article

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