2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/109953This paper studies the compatibility of having a grand unification scheme for particle physics, while at the same time having a perturbative string theory description of such a scheme on a D-brane. This is studied in a model independent approach and finds a negative result. Some additional observations related to model building on branes are made.4 pages, latex. v2: Improved discussion on impossibility on some Yukawa couplings and references added. v3:reference addedHigh Energy Physics - Theorytext