(F,Dp) bound states from the boundary state

We use the boundary state formalism to provide the full conformal descripti on of (F,Dp) bound states, These are BPS configurations that arise from a s uperposition of a fundamental string and a Dp-brane, and are charged under both the NS-NS antisymmetric tensor and the (p + 1)-form R-R potential, We construct the boundary state for these bound states by switching on a const ant electric field on the world-volume of a Dp-brane and fix its value by i mposing the Dirac quantization condition on the charges. Using the operator formalism we also derive the Dirac-Born-Infeld action and the classical su pergravity solutions corresponding to these configurations. (C) 2000 Elsevi er Science B.V. All rights reserved.