We consider a simple extension of the Standard Model by adding two Higgs triplets and a complex scalar singlet to its particle content. In this framework, the $CP$ symmetry is spontaneously broken at high energies by the complex vacuum expectation value of the scalar singlet. Such a breaking leads to leptonic $CP$ violation at low energies. The model also exhibits an $A_4\times Z_4$ flavor symmetry which, after being spontaneously broken at a high-energy scale, yields a tribimaximal pattern in the lepton sector. We consider small perturbations around the tribimaximal vacuum alignment condition in order to generate nonzero values of ${\theta }_{13}$, as required by the latest neutrino oscillation data. It is shown that the value of ${\theta }_{13}$ recently measured by the Daya Bay Reactor Neutrino Experiment can be accommodated in our framework together with large Dirac-type $CP$ violation. We also address the viability of leptogenesis in our model through the out-of-equilibrium decays of the Higgs triplets. In particular, the $CP$ asymmetries in the triplet decays into two leptons are computed and it is shown that the effective leptogenesis and low-energy $CP$-violating phases are directly linked.

• Received 11 May 2012

DOI:https://doi.org/10.1103/PhysRevD.86.076008