Testing constrained sequential dominance models of neutrinos

Abstract

Constrained sequential dominance (CSD) is a natural framework for implementing the see-saw mechanism of neutrino masses which allows the mixing angles and phases to be accurately predicted in terms of relatively few input parameters. We analyze a class of CSD($n$) models where, in the flavour basis, two right-handed neutrinos are dominantly responsible for the "atmospheric" and "solar" neutrino masses with Yukawa couplings to $({\nu }_e,{\nu }_{\mu },{\nu }_{\tau })$ proportional to $(0,1,1)$ and $(1,n,n-2)$, respectively, where $n$ is a positive integer. These coupling patterns may arise in indirect family symmetry models based on $A_4$. With two right-handed neutrinos, using a ${\chi }^2$ test, we find a good agreement with data for CSD(3) and CSD(4) where the entire PMNS mixing matrix is controlled by a single phase $\eta$, which takes simple values, leading to accurate predictions for mixing angles and the magnitude of the oscillation phase $|{\delta }_{CP}|$. We carefully study the perturbing effect of a third "decoupled" right-handed neutrino, leading to a bound on the lightest physical neutrino mass $m_1\lesssim 1$ meV for the viable cases, corresponding to a normal neutrino mass hierarchy. We also discuss a direct link between the oscillation phase ${\delta }_{CP}$ and leptogenesis in CSD($n$) due to the same see-saw phase $\eta$ appearing in both the neutrino mass matrix and leptogenesis.

34 pages, 15 figures. Version to be published in J.Phys G. Note the change in title. Clarifying comments added. Previous versions: 32 pages, 15 figures. Improved discussion of chi squared analysis, new plots added. // 29 pages, 13 figures. Minor changes and discussion about the origin of the vacuum alignments added to an Appendix

References in corpus (6)

• On the origin of neutrino flavour symmetry
• Lepton Mixing Predictions including Majorana Phases from $\Delta (6n^2)$ Flavour Symmetry and Generalised CP
• Decrypting $SO(10)$-inspired leptogenesis
• Successful $N_2$ leptogenesis with flavour coupling effects in realistic unified models
• Vacuum misalignment corrections to tri-bimaximal mixing and form dominance
• Quark mixing from Delta(6N^2) family symmetry

Cited by in corpus (5)

• Towards a complete $A_4\times SU(5)$ SUSY GUT
• Towards a complete $\Delta (27)\times SO(10)$ SUSY GUT
• Successful $N_2$ leptogenesis with flavour coupling effects in realistic unified models
• Models of Neutrino Mass, Mixing and CP Violation
• Renormalisation Group Corrections to the Littlest Seesaw Model and Maximal Atmospheric Mixing