Relations among neutrino observables in the light of a large theta_13 angle

Understand

The recent T2K and MINOS indications for a "large" theta_13 neutrino mixing angle can be accommodated in principle by an infinite number of Yukawa flavour structures in the seesaw model.

• Without considering any explicit flavour symmetry, there is an instructive exercise one can do: to determine the simplest flavour structures which can account for the data with a minimum number of parameters, simply assuming these parameters to be uncorrelated.
• This approach points towards a limited number of simple structures which show the minimum complexity a neutrino mass model must generally involve to account for the data.
• These basic structures essentially lead to only 4 relations between the neutrino observables.