A(4) Flavor Symmetry Model for Dirac-Neutrinos and Sizable U(e3)

Understand

Models based on flavor symmetries are the most often studied approaches to explain the unexpected structure of lepton mixing.

• In many flavor symmetry groups a product of two triplet representations contains a symmetric and an anti-symmetric term.
• If this product of two triplets corresponds to a Majorana mass term, then the anti-symmetric part vanishes, and in economic models tri-bimaximal mixing is achieved.
• If neutrinos are Dirac particles, the anti-symmetric part is however present and leads to deviations from tri-bimaximal mixing, in particular non-zero U(e3).