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We present a generic Lagrangian, in arbitrary spacetime dimension D, describing the interaction of a dilaton, a graviton and an antisymmetric tensor of arbitrary rank d. For each D and d, we find " solitonic " black˜p-brane solutions where˜p = ˜ d−1 and˜d = D−d−2. These solutions display a spacetime singularity surrounded by an event horizon, and are(More)
We review the status of solitons in superstring theory, with a view to understanding the strong coupling regime. These solitonic solutions are non-singular field configurations which solve the empty-space low-energy field equations (generalized, whenever possible, to all orders in α ′), carry a non-vanishing topological " magnetic " charge and are(More)
In six spacetime dimensions, the heterotic string is dual to a Type IIA string. On further toroidal compactification to four spacetime dimensions, the heterotic string acquires an SL(2, Z) S strong/weak coupling duality and an SL(2, Z) T × SL(2, Z) U target space du-ality acting on the dilaton/axion, complex Kahler form and the complex structure fields S,(More)
We reexamine the question of heterotic-heterotic string duality in six dimensions and argue that the E 8 × E 8 heterotic string, compactified on K3 with equal instanton numbers in the two E 8 's, has a self-duality that inverts the coupling, dualizes the antisymmetric tensor, acts non-trivially on the hypermultiplets, and exchanges gauge fields that can be(More)
We consider the Schwarz-Sen spectrum of elementary electrically charged massive N R = 1/2 states of the four-dimensional heterotic string and show the maximum spin 1 supermul-tiplets to correspond to extreme black hole solutions. The N L = 1 states and N L > 1 states (with vanishing left-moving internal momentum) admit a single scalar-Maxwell description(More)
The Kaluza-Klein idea of extra spacetime dimensions continues to pervade current attempts to unify the fundamental forces, but in ways somewhat different from that originally envisaged. We present a modern perspective on the role of internal dimensions in physics, focussing in particular on su-perstring theory. A novel result is the interpretation of(More)