Fermion Mass Hierarchies in Singlet-Extended Minimal-Supersymmetric-Standard-Model Quivers

In the context of type-IIA orientifold compactifications, we discuss the fermion masses in a two−singlet-extended minimal-supersymmetric-standard-model four-stack quiver with U(3)×Sp(1)×U(1)×U(1) gauge symmetry. The corresponding effective superpotential exhibits hierarchical coupling term scales giving a partial solution to the fermion masses problem. Using the known data with upper bound neutrino masses m_ντ≲ 2 eV, we estimate the relevant scales for the model.