Five-branes, KK monopoles and T-duality

We construct the explicit world-volume effective actions of the type IIB NS5-brane and KK monopole. These objects are obtained through a T-duality transformation from the IIA KK monopole and the IIA NS5-brane respectively. We show that the world-volume field content of these actions is precisely that necessary to describe their world-volume solitons. The IIB NS5-brane effective action is shown to be related to the D5-brane's by an S-duality transformation, suggesting the way to construct (p,q) 5-brane multiplets. The IIB KK monopole is described by a gauged sigma model, in agreement with the general picture for KK monopoles, and behaves as a singlet under S-duality. We derive the explicit T-duality rules NS5-brane ↔ KK, which we use for the construction of the previous actions, as well as NS5 ↔ NS5, and KK ↔ KK.