Orientifolds, branes, and duality of 4D gauge theories Original Research Article

Recently, a D-brane construction in type IIA string theory was shown to yield the electric/magnetic duality of four-dimensional N = 1 supersymmetric U(Nc) gauge theories with Nf flavours of quark. We present here an extension of that construction which yields the electric/magnetic duality for the SO(Nc) and USp(Nc) gauge theories with Nf quarks, by adding an orientifold plane which is consistent with the supersymmetry. Due to the intersection of the orientifold plane with the NS-NS fivebranes already present, new features arise which are crucial in determining the correct final structure of the dualities.