Finite modular groups and lepton mixing

Abstract:We perform a detailed analysis of ∆(6n 2 ) family symmetry combined with a generalised CP symmetry in the lepton sector, breaking to different remnant symmetries G ν in the neutrino and G l in the charged lepton sector, together with different remnant CP symmetries in each sector. We discuss the resulting mass and mixing predictions for G ν = Z 2 with G l = K 4 , Z p , p > 2 and G ν = K 4 with G l = Z 2 . All cases correspond to the preserved symmetry smaller than the full Klein symmetry, as in the semi-direct approach, leading to predictions which depend on a single undetermined real parameter, which mainly determines the reactor angle. We focus on five phenomenologically allowed cases for which we present the resulting predictions for the PMNS parameters as a function of n, as well as the predictions for neutrinoless double beta decay.

“…Feruglio-Hagedorn mixing [64][65][66][67] can be obtained in the case of ϕ 1 = ±π/4, ±3π/4. Now we consider the permutations of the rows and the columns, i.e.…”

Section: Jhep12(2014)007mentioning

confidence: 99%

Generalised CP and Δ(6n 2) family symmetry in semi-direct models of leptons

Ding

King

Neder

2014

“…[31] and [32]. It is associated with the group A 5 breaking into a Z 3 symmetry in the charged-lepton sector and the Klein symmetry in the neutrino sector.…”

Section: Jhep12(2014)122mentioning

confidence: 99%

Testing solar lepton mixing sum rules in neutrino oscillation experiments

Ballett

King

Luhn

et al. 2014

Small discrete family symmetries such as S 4 , A 4 or A 5 may lead to simple leading-order predictions for the neutrino mixing matrix such as the bimaximal, tribimaximal or golden ratio mixing patterns, which may be brought into agreement with experimental data with the help of corrections from the charged-lepton sector. Such scenarios generally lead to relations among the parameters of the physical leptonic mixing matrix known as solar lepton mixing sum rules. In this article, we present a simple derivation of such solar sum rules, valid for arbitrary neutrino and charged lepton mixing angles and phases, assuming only θ ν 13 = θ e 13 = 0. We discuss four leading-order neutrino mixing matrices with θ ν 13 = 0 which are well motivated from family symmetry considerations. We then perform a phenomenological analysis of the scope to test the resulting four solar sum rules, highlighting the complementarity between next-generation neutrino oscillation experiments such as the reactor experiment JUNO and a superbeam experiment.

“…The first class of theories exhibited very predictive mass textures [8][9][10][11][12][13][14][15][16][16][17][18][19][20][21][22][23][24][25] and provided a certain protection from flavour violating processes [26][27][28][29][30][31][32][33][34]. However, the 2011 discovery of a nonvanishing, and relatively large, leptonic reactor angle [35][36][37][38][39] has raised strong doubts on the use of non-Abelian discrete models, whose most common prediction was a vanishing reactor angle.…”

Section: Introductionmentioning

confidence: 99%

The minimal flavour violating axion

Arias-Aragón

Merlo

2017

The solution to the Strong CP problem is analysed within the Minimal Flavour Violation (MFV) context. An Abelian factor of the complete flavour symmetry of the fermionic kinetic terms may play the role of the Peccei-Quinn symmetry in traditional axion models. Its spontaneous breaking, due to the addition of a complex scalar field to the Standard Model scalar spectrum, generates the MFV axion, which may redefine away the QCD theta parameter. It differs from the traditional QCD axion for its couplings that are governed by the fermion charges under the axial Abelian symmetry. It is also distinct from the so-called Axiflavon, as the MFV axion does not describe flavour violation, while it does induce flavour non-universality effects. The MFV axion phenomenology is discussed considering astrophysical, collider and flavour data.