Radiative Fermion Masses in Local D-Brane Models

Understand

In the context of D-brane model building, we present a realistic framework for generating fermion masses that are forbidden by global symmetries.

• We show that the string theoretical Large volume scenario circumvents the standard lore that fermion masses generated by loop effects are too small in generic gravity mediated scenarios.
• We argue that the fact that in toric singularity models, the up quark masses have always a zero eigenvalue, corresponding to the lightest generation, is due to the presence of approximate global symmetries that we explicitly identify in del Pezzo singularities.
• These symmetries are broken by global effects and therefore proportional to inverse powers of the volume.