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We analyse D-branes on orbifolds with discrete torsion, extending earlier results. We analyze certain Abelian orbifolds of the type C 3 /Γ, where Γ is given by Z m × Z n , for the most general choice of discrete torsion parameter. By comparing with the AdS/CFT correspondence, we can consider different geometries which give rise to the same physics. This(More)
We study marginal and relevant supersymmetric deformations of the N = 4 super-Yang-Mills theory in four dimensions. Our primary innovation is the interpretation of the moduli spaces of vacua of these theories as non-commutative spaces. The construction of these spaces relies on the representation theory of the related quantum algebras, which are obtained(More)
We present evidence for renormalization group fixed points with dual magnetic descriptions in fourteen new classes of four-dimensional N = 1 supersymmetric models. Nine of these classes are chiral and many involve two or three gauge groups. These theories are generalizations of models presented earlier by Seiberg, by Kutasov and Schwimmer, and by the(More)
Supersymmetric gauge theories in four dimensions can display interesting non-perturbative phenomena. Although the superpotential dynamically generated by these phenomena can be highly nontrivial, it can often be exactly determined. We discuss some general techniques for analyzing the Wilsonian superpotential and demonstrate them with simple but non-trivial(More)
We consider the propagation of Type I open superstrings on orb-ifolds with four non-compact dimensions and N = 1 supersymmetry. In this paper, we concentrate on a non-trivial Z Z 2 × Z Z 2 example. We show that consistency conditions, arising from tadpole cancellation and algebraic sources, require the existence of three sets of Dirichlet 5-branes. We(More)
High-potential iron-sulfur protein (HiPIP) has recently been shown to function as a soluble mediator in photosynthetic electron transfer between the cytochrome bc1 complex and the reaction-center bacteriochlorophyll in some species of phototrophic proteobacteria, a role traditionally assigned to cytochrome c2. For those species that produce more than one(More)