Predictions from scoto-seesaw with A4 modular symmetry

Abstract

This paper's novelty lies in introducing a hybrid scoto-seesaw model rooted in A4 discrete modular symmetry leading to several interesting phenomenological implications. The scoto-seesaw framework leads to generation of one mass square difference (Δmatm2) using the type-I seesaw mechanism at the tree level. Additionally, the scotogenic contribution is vital in obtaining the other mass square difference (Δmsol2) at the loop level, thus providing a clear interpretation of the two different mass square differences. The non-trivial transformation of Yukawa couplings under the A4 modular symmetry helps to explore neutrino phenomenology with a specific flavor structure of the mass matrix. In addition to predictions for neutrino mass ordering, mixing angles and CP phases, this setup leads to precise predictions for ∑mi as well as |mee|. In particular, the model predicts ∑mi∈(0.073,0.097) eV and |mee|∈(3.15,6.66)×10−3 eV range; within reach of upcoming experiments. Furthermore, our model is also promising for addressing lepton flavor violations, i.e., ℓα→ℓβγ, ℓα→3ℓβ and μ−e conversion rates while staying within the realm of current experimental limits.