2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/50832We propose a new approach for coupling the type II superstring to the Ramond-Ramond background of D-branes in the RNS formalism, alternative to introducing RR vertex operators. It is based on the mixing between Ramond-Ramond p-form excitations in the closed string spectrum and transversally polarized excitations in the open string spectrum.5 pages, minor changes, references addedHigh Energy Physics - Theorytext