Recently Banks, Douglas, and Seiberg have shown that the world-volume theory of a three-brane of type IIB theory in the presence of a configuration of four Dirichlet seven-branes and an orientifold plane is described by an $N=2\mathrm{}$ supersymmetric SU(2) gauge theory with four quark flavors in 3+1 dimensions. In this paper we show how the BPS mass formula for $N=2\mathrm{}$ supersymmetric gauge theory arises from masses of open strings stretched between the three-brane and the seven-brane along appropriate geodesics.

• Received 10 September 1996

DOI:https://doi.org/10.1103/PhysRevD.55.2501