From quiver diagrams to particle physics
  Recent scenarios of phenomenologically realistic string compactifications involve the existence of gauge sectors localized on D-branes at singular points of Calabi-Yau threefolds. The spectrum and interactions in these gauge sectors are determined by the local geometry of the singularity, and can be encoded in quiver diagrams. We discuss the physical models arising for the simplest case of orbifold singularities, and generalize to non-orbifold singularities and orientifold singularities. Finally we show that relatively simple singularities lead to gauge sectors surprisingly close to the standard model of elementary particles. 
Angel M. Uranga