CKM and Tri-bimaximal MNS Matrices in a SU(5) x T' Model

by Mu-Chun Chen (University of California, Irvine)

Friday 3 Aug 2007, 14:00 → 15:00 Europe/Zurich

TH AMPHITHEATRE (CERN)

In this talk, I will present a SU(5) unified model combined with a family symmetry based on the double covering tetrahedral group, T'. Our model successfully gives rise to tri-bimaximal neutrino mixing as well as realistic CKM matrix elements for the quarks. The Georgi-Jarlskog relations for three generations are also obtained. Due to the T' transformation property of the matter fields, the b-quark mass can be generated only when the T' symmetry is broken, giving a dynamical origin for the hierarchy between mb and mt. There are only nine operators allowed in the Yukawa sector up to at least mass dimension seven due to an additional Z12 x Z12 symmetry, which also forbids, up to some high orders, operators that lead to proton decay. The resulting model has a total of nine parameters in the charged fermion and neutrino sectors, and hence is very predictive. In addition to the prediction for theta13 ~ 0.05, the model gives rise to a new quark-lepton complimentarity relation between the solar and Cabibbo angles, which is a consequence of the Georgi-Jarlskog relations in the quark sector. This deviation could account for the difference between the experimental best fit value for the solar mixing angle and the value predicted by the tri-bimaximal mixing matrix.