CP violation from finite groups

We propose a complex extension of µτ permutation antisymmetry in the neutrino Majorana matrix M ν . The latter can be realized for the Lagrangian by appropriate CP transformations on the neutrino fields. The resultant form of M ν is shown to be simply related to that with a complex (CP) extension of µτ permutation symmetry, with identical phenomenological consequences, though their group theoretic origins are quite different. We investigate those consequences in detail for the minimal seesaw induced by two strongly hierarchical right-chiral neutrinos N 1 and N 2 with the result that the Dirac phase is maximal while the two Majorana phases are either 0 or π. We further provide an uptodate discussion of the ββ0ν process vis-a-vis ongoing and forthcoming experiments. Finally, a thorough treatment is given of baryogenesis via leptogenesis in this scenario, primarily with the assumption that the lepton asymmetry produced by the decays of N 1 only matters here with the asymmetry produced by N 2 being washed out. Tight upper and lower bounds on the mass of N 1 are obtained from the constraint of obtaining the correct observed range of the baryon asymmetry parameter and the role played by N 2 is elucidated thereafter. The mildly hierarchical right-chiral neutrino case (including the quasidegenerate possibility) is discussed in an appendix.

Section: Complex Extension Of µτ Antisymmetrymentioning

confidence: 99%

Consequences of minimal seesaw with complex μτ antisymmetry of neutrinos

Samanta

Roy

Ghosal

2018

“…Then the two symmetries act on the same space and CP µτ induces the following automorphism on Z 8 [50][51][52][53]:…”

Section: Jhep01(2017)068mentioning

confidence: 99%

“…[39] for a review. In contrast, residual CP symmetries have also been considered to determine the mixing angles (and CP phases) [40][41][42][43][50][51][52][53].…”

Section: Introductionmentioning

confidence: 99%

“…The combination of two noncommuting symmetries cannot be arbitrary and needs to fulfill some compatibility rules so that the whole group closes. 3 In fact, some consistency conditions are required to combine a CP symmetry with a nonabelian discrete flavor group [50][51][52][53]. For this reason, we choose the simplest setting where we combine an abelian discrete symmetry with CP µτ in a consistent but nontrivial way.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Mu-tau reflection symmetry with a texture-zero

Nishi

Sánchez-Vega

2017

Abstract:The µτ -reflection symmetry is a simple symmetry capable of predicting all the unknown CP phases of the lepton sector and the atmospheric angle but too simple to predict the absolute neutrino mass scale or the mass ordering. We show that by combining it with a discrete abelian symmetry in a nontrivial way we can additionally enforce a texture-zero and obtain a highly predictive scenario where the lightest neutrino mass is fixed to be in the few meV range for two normal ordering (NO) solutions or in the tens of meV in one inverted ordering (IO) solution. The rate for neutrinoless double beta decay is predicted to be negligible for NO or have effective mass m ββ ≈ 14-29 meV for IO, right in the region to be probed in future experiments.

“…[35][36][37][38][39]. The interplay between flavor symmetries and CP symmetries has been generally discussed in [40,41]. In addition, there are other theoretical approaches involving both family symmetry and CP violation [42][43][44][45][46][47][48][49][50][51][52][53].…”

Section: Jhep12(2014)007mentioning

confidence: 99%

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

Ding

King

Neder

2014

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.