Electromagnetic dipole radiation of oscillating D-branes

Abstract

I emphasize analogy between Dp-branes in string theories and solitons in gauge theories comparing their common properties and showing differences. We will show that for certain excitations of the string/D3-brane system Neumann boundary conditions emerge from the Born-Infeld dynamics. The excitations which are coming down the string with a polarization along a direction parallel to the brane are almost completely reflected. For the wavelengths much larger than the string scale only a small fraction of the energy escapes in the form of dipole radiation. The physical interpretation is that a string attached to the 3-brane manifests itself as an electric charge, and waves on the string cause the end point of the string to freely oscillate and produce electromagnetic dipole radiation in the asymptotic outer region. The magnitude of emitted power is in fact exactly equal to the one given by Thompson formula in ordinary electrodynamics.