2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/52173We calculate tree level three and four point scattering amplitudes in type II string models with matter fields localized at the intersections of D-brane wrapping cycles. The analysis of the three point amplitude is performed in the context of Yukawa couplings and it is seen that a natural mechanism for the generation of a mass hierarchy arises. The four point amplitude for fermions at the intersection of four independent stacks of D-branes is then determined.8 pages, 3 figures. To appear in the proceedings of the 2nd international conference on String Phenomenology 2003, Durham, England, 29th July-4th August, 2003. References addedHigh Energy Physics - Theorytext