Predicting theta_13 and the Neutrino Mass Scale from Quark Lepton Mass
  Hierarchies
  Flavour symmetries of Froggatt-Nielsen type can naturally reconcile the large
quark and charged lepton mass hierarchies and the small quark mixing angles
with the observed small neutrino mass hierarchies and their large mixing
angles. We point out that such a flavour structure, together with the measured
neutrino mass squared differences and mixing angles, strongly constrains yet
undetermined parameters of the neutrino sector. Treating unknown O(1)
parameters as random variables, we obtain surprisingly accurate predictions for
the smallest mixing angle, sin^2(2 theta_13) = 0.07 (+0.11)(-0.05), the
smallest neutrino mass, m_1 = 2.2 (+1.7)(-1.4) x 10^-3 eV, and one Majorana
phase, alpha_21 / pi = 1.0 (+0.2)(-0.2).
