A flavor symmetry model for bilarge leptonic mixing and the lepton masses

Abstract

We present a model for leptonic mixing and the lepton masses based on flavor symmetries and higher-dimensional mass operators. The model predicts bilarge leptonic mixing (i.e., the mixing angles θ 12 and θ 23 are large and the mixing angle θ 13 is small) and an inverted hierarchical neutrino mass spectrum. Furthermore, it approximately yields the experimental hierarchical mass spectrum of the charged leptons. The obtained values for the leptonic mixing parameters and the neutrino mass squared differences are all in agreement with atmospheric neutrino data, the Mikheyev-Smirnov-Wolfenstein large mixing angle solution of the solar neutrino problem, and consistent with the upper bound on the reactor mixing angle. Thus, we have a large, but not close to maximal, solar mixing angle θ 12 , a nearly maximal atmospheric mixing angle θ 23 , and a small reactor mixing angle θ 13 . In addition, the model predicts θ 12 ≃ π 4 − θ 13 .

Seesaw mechanism in quark-lepton complementarity

“…Note that these cases are initially generated as well, but they might be filtered out later by Eq. (24 4. We omit texture sets with anarchical M R (matrices just filled with entries "1"), since such structure-less textures do, in general, not yield much useful information.…”

“…A complementary approach to the solar angle seems, on the other hand, to be suggested by the tri-bimaximal mixing scheme [17]. The properties of QLC have been studied in various respects: as a result of deviations from bimaximal mixing [18], in connection with sum rules [19], with emphasis on phenomenological implications [20], together with parameterizations of U PMNS in terms of θ C [21], in view of statistical arguments [22], in conjunction with renormalization group effects [23], and in model building realizations [24].…”

“…However, the appropriate absolute mass scale will be implicitly determined in order to satisfy Eq. (24).…”

Is there maximal mixing in the lepton sector?

“…mixing parameters, which is clearly not compatible with the assumption of a neutrino mass matrix without any structure [47] and would require some theoretical reason. One option is employing flavor symmetries that enforce virtually maximal atmospheric mixing (see, e.g., [33][34][35][36][37][38][39]). On the other hand, if maximal mixing is excluded experimentally by a broad margin, this will favor either a numerical coincidence without an underlying symmetry or models which can accommodate or even predict significant deviations.…”

Quark lepton complementarity and renormalization group effects

“…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].…”