2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/51638We discuss the construction of four dimensional non-supersymmetric models obtained from configurations of D6-branes intersecting at angles. We present the first examples of string GUT models which break exactly to the Standard Model (SM) at low energy. Even though the models are non supersymmetric (SUSY), the demand that some open string sectors preserve N=1 SUSY creates gauge singlet scalars that break the extra anomaly free U(1)'s generically present in the models, predicting $s{\tilde ν}_R$'s and necessarily creating Majorana mass terms for right handed neutrinos.6 pages, Part of a talk given to SUSY'02. Contribution to the ProceedingsHigh Energy Physics - Theorytext