Fermion masses and mixings from heterotic orbifold models

We search for a possibility of getting realistic fermion mass ratios and mixing angles from renormalizable couplings on the Z6‐I heterotic orbifold with one pair of Higgs doublets. In the quark sector, we find cases with reasonable results if we ignore the first family. In the lepton sector, we can fit the charged lepton mass ratios, the neutrino mass squared difference ratio, and the lepton mixing angles, considering all three families.