SUPERSYMMETRIC GAUGE-THEORIES FROM BRANES AND ORIENTIFOLD 6-PLANES

We study brane configurations in the presence of orientifold six-plane s. After deriving the curves for N = 2 supersymmetric SU(N-c) gauge th eories with one flavor in the symmetric or antisymmetric representatio n and Nf fundamental flavors, we rotate the brane configuration, reduc ing the supersymmetry to N = 1. For the case of an antisymmetric flavo r and less than two fundamental flavors, nonperturbative effects lead to a brane configuration that is topologically a torus. Using the desc ription of the orientifold six-planes as D-n singularities we discuss the Higgs branches for N = 2 brane configurations with Sp/SO gauge gro ups and the related N = 1 theories with tensor representations.