We provide a systematic approach to describing the Ramond-Ramond (RR) fields
as elements in twisted differential K-theory. This builds on a series of
constructions by the authors on geometric and computational aspects of twisted
differential K-theory, which to a large extent were originally motivated by
this problem. In addition to providing a new conceptual framework and a
mathematically solid setting, this allows us to uncover interesting and novel
effects. Explicitly, we use our recently constructed Atiyah-Hirzebruch spectral
sequence (AHSS) for twisted differential K-theory to characterize the RR fields
and their quantization, which involves interesting interplay between geometric
and topological data. We illustrate this with the examples of spheres, tori,
and Calabi-Yau threefolds.Comment: 41 pages, comments welcom