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arXiv · hep-th/9510017

Dirichlet-Branes and Ramond-Ramond Charges

Joseph Polchinski
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Abstract

We show that Dirichlet-branes, extended objects defined by mixed Dirichlet-Neumann boundary conditions in string theory, break half of the supersymmetries of the type~II superstring and carry a complete set of electric and magnetic Ramond-Ramond charges. We also find that the product of the electric and magnetic charges is a single Dirac unit, and that the quantum of charge takes the value required by string duality. This is strong evidence that the Dirchlet-branes are intrinsic to type II string theory and are the Ramond-Ramond sources required by string duality. We also note the existence of a previously overlooked 9-form potential in the IIa string, which gives rise to an effective cosmological constant of undetermined magnitude.

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Joseph Polchinski. 1995-11-08. Dirichlet-Branes and Ramond-Ramond Charges. https://doi.org/10.1103/physrevlett.75.4724

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