2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/194839We construct the Zinn-Justin-Batalin-Vilkovisky action for tachyons and gauge bosons from Witten's 3-string vertex of the bosonic open string without gauge fixing. Through canonical transformations, we find the off-shell, local, gauge-covariant action up to 3-point terms, satisfying the usual field theory gauge transformations. Perturbatively, it can be extended to higher-point terms. It also gives a new gauge condition in field theory which corresponds to the Feynman-Siegel gauge on the world-sheet.12 pages, 0 figures. v2: more than one paragraph added before eqn. (29) to discuss how to find the transformations in eqn.(29) and (30), Typos corrected. To appear in Phys. Rev. DHigh Energy Physics - Theorytext