ABSTRACT
This chapter presents the simplest brane configurations of string theory. It discusses the fundamental string solution, the solitonic Neveu-Schwarz 5-brane solution and the so-called Dp- branes in a flat ten-dimensional spacetime. In some sense the so-called D-branes are the most interesting and intriguing configurations of string theory. They are non-trivial solutions of the supergravity field equations of type IIA or IIB that are charged under one of the antisymmetric potentials of the R-R sector. The structure of the type IIB action is very similar to that in type IIA theory, the only difference being in the field content of the R-R sector. In order to remove the dilaton factor from the curvature term and to avoid mixed graviton-dilaton propagators, it is convenient to rewrite the action in the more conventional Einstein frame.
