Quark-lepton complementarity relation and neutrino mass hierarchy

Abstract

Latest measurements have revealed that the deviation from a maximal solar mixing angle is approximately the Cabibbo angle (i.e. QLC relation). We argue that it is not plausible that this deviation from maximality, be it a coincidence or not, comes from the charged lepton mixing. Consequently we have calculated the required corrections to the exactly bimaximal neutrino mass matrix ansatz necessary to account for the solar mass difference and the solar mixing angle. We point out that the relative size of these two corrections depends strongly on the hierarchy case under consideration. We find that the inverted hierarchy case with opposite CP parities, which is known to guarantee the RGE stability of the solar mixing angle, offers the most plausible scenario for a high energy origin of a QLC-corrected bimaximal neutrino mass matrix. This possibility may allow us to explain the QLC relation in connection with the origin of the charged fermion mass matrices.

Predicting neutrino parameters from SO(3) family symmetry and quark-lepton unification

“…has recently been the subject of much speculation [4,5,6,7,8,9,10]. The interest arises from the possibility that this so-called quark-lepton complementarity (QLC) relation could be a signal of some high scale quark-lepton unification.…”

Quark lepton complementarity and renormalization group effects

“…1 we show the range of QLC values of θ 12 obtained from eqs. (7,9) by varying (α 3 − α 1 ). This variation gives …”

“…There is a number of attempts to reproduce the QLC relations on the basis of already existing ideas about fermion mass matrices [3,8,9,10]. Usually they lead to too small deviations of θ 12 from π/4, and therefore require further corrections or deviations from the bimaximal mixing or from the Cabibbo mixing already in the lowest order.…”

“…The simplest possibility is the SU (2) L × SU (2) R × SU (4) C model that implements the quark-lepton symmetry in the most straightforward way [8,10]. Phenomenology of schemes with QLC relations has been extensively studied [4,9,11,12].…”

Neutrino mass and New physics

“…If the leptonic mass matrix has similar structure to the d-quark mass matrix with Gatto-Sartori-Tonin (GST) relation one would expect θ l ∼ m e /m µ ≈ θ C /3 and deviation from maximal mixing θ l / √ 2 = 1/3 √ 2θ C turns out to be too small [86]. There are several proposals to enhance the shift angle.…”