Robert G Leigh

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We show that manifolds of fixed points, which are generated by exactly marginal operators, are common in N=1 supersymmetric gauge theory. We present a unified and simple prescription for identifying these operators, using tools similar to those employed in two-dimensional N=2 supersymmetry. In particular we rely on the work of Shifman and Vainshtein(More)
We show that configurations of multiple D-branes related by SU (N) rotations will preserve unbroken supersymmetry. This includes cases in which two D-branes are related by a rotation of arbitrarily small angle, and we discuss some of the physics of this. In particular, we discuss a way of obtaining 4D chiral fermions on the intersection of D-branes. We also(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 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 discuss string propagation in the near-horizon geometry generated by Neveu-Schwarz fivebranes, Kaluza-Klein monopoles and fundamental strings. When the fivebranes and KK monopoles are wrapped around a compact four-manifold M, the geometry is AdS 3 × S 3 /Z Z N × M and the spacetime dynamics is expected to correspond to a local two dimensional conformal(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)
We construct the most general supersymmetric configuration of D2-branes and D6-branes on a 6-torus. It contains arbitrary numbers of branes at relative U (3) angles. The corresponding supergravity solutions are constructed and expressed in a remarkably simple form, using the complex geometry of the compact space. The spacetime supersymmetry of the(More)
We show that there is a natural action of SL(2, Z) on the two-point functions of the energy momentum tensor and of higher-spin conserved currents in three-dimensional CFTs. The dynamics behind the S-operation of SL(2, Z) is that of an irrelevant current-current deformation and we point out its similarity to the dynamics of a wide class of three-dimensional(More)
We discuss the implementation of electric-magnetic duality transformations in four-dimensional gravity linearized around Minkowski or (A)dS 4 backgrounds. In the presence of a cosmological constant duality generically modifies the Hamiltonian, nevertheless the bulk dynamics is unchanged. We pay particular attention to the boundary terms generated by the(More)
We construct string target spacetimes with AdS 3 × X geometry, which have an N = 2 spacetime superconformal algebra. X is found to be a U (1) fibration over a manifold which is a target for an N = 2 worldsheet conformal field theory. We emphasize theories with free field realizations where in principle it is possible to compute the full one-particle string(More)