Paper detail

Properties of Fermion Mixings in Intersecting D-brane Models

We consider the Yukawa couplings for quarks and leptons in the context of Pati-Salam model using intersecting D-brane models where the Yukawa coupling matrices are rank one in a simple choice of family replication. The CKM mixings can be explained by perturbing the rank 1 matrix using higher order terms involving new Higgs fields available in the model. We show that the near bi-large neutrino mixing angles can be naturally explained, choosing the light neutrino mass matrix to be type II seesaw dominant. The predicted value of U_{e3} is in the range \simeq 0.05-0.15. In the quark sector, V_{cb} is naturally close to the strange/bottom quark mass ratio and we obtain an approximate relation V_{ub} V_{cb} \simeq (m_s/m_b)^2 V_{us}. The geometrical interpretations of the neutrino mixings are also discussed.