D-brane Wess-Zumino actions, T-duality and the cosmological constant

A geometrical formulation of the T-duality rules for type II superstring Ramond-Ramond fields is presented. This is used to derive the Wess-Zumino terms in superstring D-brane actions, including terms proportional to the mass parameter of the IIA theory, thereby completing partial results in the literature. For non-abelian world-volume gauge groups the massive type IIA D-brane actions contain non-abelian Chern-Simons terms for the Born-Infeld gauge potential, implying a quantization of the IIA cosmological constant.