2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/210451We show that strictly local observables with arbitrarily small support in space-time exist in covariant free open bosonic string field theory. The main ingredient of the proof is a modified version of the well known DDF operators, which we rigourously define. This result allows in principle the definition of a net of local observable algebras and should be considered as a first step towards the application of algebraic quantum field theory to this caseMathematical PhysicsHigh Energy Physics - Theorytext