2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/104646We generalize the idea of boundary states to open string channel. They describe the emission and absorption of the open string in the presence of intersecting D-branes. We study the algebra between such states under the star products of string field theory and confirm that they are projectors in a generalized sense. Based on this observation, we propose a modular dual description of Witten's open string field theory which seems to be an appropriate set-up to study D-branes by string field theory.13 pages, 4 figures, using a class file qts-proc.cls, Proceeding of the workshop QTS-4, Varna, Burgalia (16-21 August 2005), some correctionsHigh Energy Physics - Theorytext