2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/217722We address the problem of describing different closed string backgrounds in background independent open string field theory: A shift in the closed string background corresponds to a collective excitation of open strings. As an illustration we apply the formalism to the case where the closed string background is a group manifold.Based on a talk given at the BW2007 workshop "Challenges Beyond the Standard Model", Kladovo, Serbia. To be published in Fortschritte der PhysikHigh Energy Physics - Theorytext