Completing constrained flavor violation: Lepton masses, neutrinos, and leptogenesis

Abstract

Constrained flavor violation is a recent proposal for predicting the down-quark Yukawa matrix in terms of those for up quarks and charged leptons. We study the viability of CFV with respect to its predictions for the lepton mass ratios, showing that this remains a challenge, and suggest some possible means for improving this shortcoming. We then extend CFV to include neutrinos, and show that it leads to interesting predictions for hierachical heavy neutrinos, and leptogenesis dominated by decays of the second heaviest one ("N2 leptogenesis"), as well as the possibility of low-scale leptoquark-mediated exotic decays.

Perspectives for tests of neutrino mass generation at the GeV scale: Experimental reach versus theoretical predictions

“…Various models have been shown to describe the neutrino oscillation parameters within their 3σ range [55][56][57][58][59][60] using a variety of flavor symmetries such as A 5 [61][62][63][64][65], S 4 [66][67][68][69][70], A 4 [71][72][73][74][75][76][77], and Δ-groups such as Δð27Þ, Δð48Þ, Δð54Þ, Δð6n 2 Þ and Δð3n 2 Þ for n ∈ N [78][79][80][81][82][83][84][85][86][87]. Additional phenomena, such as leptogenesis, can be also be explained [88][89][90][91][92] in such models. From a different perspective, the structure of the mass matrices and their consequences without considering the origin in terms of a flavor symmetry have been considered; see e.g.…”