BPS states on a three-brane probe

Abstract

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 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 supersymmetric gauge theory arises from masses of open strings stretched between the three-brane and the seven-brane along appropriate geodesics.