Abstract

Motivated by recent results from neutrino experiments, we study the neutrino masses and mixing in the framework of a SUSY $SU(5)\times \mathbb{A}_{4} $ model. The hybrid of Type I and Type II seesaw mechanisms leads to the nonzero value of the reactor angle $\theta_{13}\neq 0$ and to the recently disfavored maximal atmospheric angle $\theta_{23} \neq45^{\circ}$ by the NOvA experiment. The phenomenological consequences of the model are studied for both normal and inverted mass hierarchies. The obtained ranges for the effective Majorana neutrino mass $m_{\beta \beta}$, the electron neutrino mass $m_{\nu_{e}}$, and the $CP$ violating phase $\delta_{CP}$ lie within the current experimental allowed ranges where we find that the normal mass hierarchy is favored over the inverted one.

Highlights

  • The neutrino oscillation experiments performed in the past two decades provided many decisive evidences of nonzero neutrino masses and large neutrino mixing [1,2,3,4,5,6]

  • Concerning neutrino masses, the current neutrino oscillation experiments are only sensitive to mass-squared differences where we distinguish between two mass hierarchies: normal mass hierarchy (NH) where m1 < m2 < m3 and inverted mass hierarchy (IH) where m3 < m1 < m2

  • By using the above definitions and the limits from experiments—see Eq (3.3)—we plot in Fig. 3 mee as a function of the lightest neutrino mass for both mass hierarchies where the Majorana phases α and β are allowed to vary in the range 1⁄20 − 2πŠ; we find that the 3σ allowed regions for the effective Majorana mass are meeðeVÞ ∈ 1⁄20.00017; 0.06084Š, which corresponds to m1ðeVÞ ∈ 1⁄20.00012; 0.08267Š for the normal hierarchy, and meeðeVÞ ∈ 1⁄20.02286; 0.05878Š, which corresponds to m3ðeVÞ ∈ 1⁄20.00144; 0.05879Š for the inverted hierarchy

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Summary

INTRODUCTION

The neutrino oscillation experiments performed in the past two decades provided many decisive evidences of nonzero neutrino masses and large neutrino mixing [1,2,3,4,5,6]. The deviation from TBM in flavor symmetry-based models can arise from (i) the diagonalization of the charged lepton mass matrix [17], (ii) perturbing the vacuum expectation value (VEV) alignment [18], (iii) the Yukawa sector [19], or (iv) the Majorana sector [16,20] These deviations are generally realized by introducing next-to-leading-order effective operators while. That the required deviations from the TBM matrix can be interpreted as the interplay of two different seesaw mechanisms making what is known as hybrid neutrino masses This hybrid has been used by many authors to account for the nonzero reactor angle θ13 ≠ 0 in the framework of the SM and GUTs; see, for example, Ref. We add in the same appendix a brief discussion on the well-known dangerous four- and five-dimensional operators leading to the rapid proton decay and show how they are suppressed in our model due to the flavor symmetry

SUð5Þ GUT WITH A4 FLAVOR SYMMETRY
Implementing A4 in neutrino sector
TBM from Type I seesaw mechanism
Deviation using Type II seesaw mechanism
Mass-squared differences and mixing angles
PHENOMENOLOGICAL IMPLICATIONS
Neutrinoless double beta decay
Tritium beta decay
Sum of neutrino masses
Dirac CP violation
CONCLUSION
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