Aspects of supertubes

We find supersymmetric solutions of the D4-brane Born-Infeld action describing D2 supertubes ending on an arbitrary curve inside a D4-brane. From the D4-brane point of view, these are dyonic strings. We also consider various higher dimensional extensions of the usual supertubes, involving expanded D4- and D3-brane configurations. Finally, considering the worldsheet theory for open strings on a supertube, we show that this configuration is an exact solution to all orders in alpha'. Further the causal structure of the open-string metric provides new insight into the arbitrary cross-section of the supertube solutions. From this point of view, it is similar to the arbitrary profile that appears for plane waves. (author)