Mu-tau reflection symmetry with a texture-zero

The neutrino µ-τ reflection symmetry has been attracting a lot of attention as it predicts the interesting results θ 23 = π/4 and δ = ±π/2. But it is reasonable to consider breakings of such a symmetry either from the theoretical considerations or on the basis of experimental results. We thus perform a systematic study for the possible symmetrybreaking patterns and their implications for the mixing parameters. The general treatment is applied to some specific symmetry breaking arising from the renormalization group effects for illustration.

Section: Jhep09(2017)023supporting

confidence: 71%

Breakings of the neutrino μ-τ reflection symmetry

Zhao

2017

“…The complex invariance condition in (2.1) can be obtained by the means of a CP transformation [49][50][51][52][53][54][55][56][57][58][59][60][61][62][63][64][65] on the neutrino fields as…”

Section: Complex Extension Of µτ Antisymmetrymentioning

confidence: 99%

Consequences of minimal seesaw with complex μτ antisymmetry of neutrinos

Samanta

Roy

Ghosal

2018

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.

“…One can also construct a minimal high energy group from a bottom-up approach knowing the symmetry in the neutrino sector and then finding the symmetry in the charged lepton sector with the automorphism condition as described in refs. [31,32].…”

Section: Jhep12(2017)030mentioning

confidence: 99%

Generalized ℤ2 × ℤ2 in scaling neutrino Majorana mass matrix and baryogenesis via flavored leptogenesis

Sinha

Samanta

Ghosal

2017

Abstract:We investigate the consequences of a generalized Z 2 ×Z 2 symmetry on a scaling neutrino Majorana mass matrix. It enables us to determine definite analytical relations between the mixing angles θ 12 and θ 13 , maximal CP violation for the Dirac type and vanishing for the Majorana type. Beside the other testable predictions on the low energy neutrino parameters such as ββ 0ν decay matrix element |M ee | and the light neutrino masses m 1,2,3 , the model also has intriguing consequences from the perspective of leptogenesis. With the assumption that the required CP violation for leptogenesis is created by the decay of lightest (N 1 ) of the heavy Majorana neutrinos, only τ -flavored leptogenesis scenario is found to be allowed in this model. For a normal (inverted) ordering of light neutrino masses, θ 23 is found be less (greater) than its maximal value, for the final baryon asymmetry Y B to be in the observed range. Besides, an upper and a lower bound on the mass of N 1 have also been estimated. Effect of the heavier neutrinos N 2,3 on final Y B has been worked out subsequently. The predictions of this model will be tested in the experiments such as nEXO, LEGEND, GERDA-II, T2K, NOνA, DUNE etc.