Leptonic CP Violation Induced by Approximately mu-tau Symmetric Seesaw Mechanism

Abstract

Assuming a minimal seesaw model with two heavy neutrinos (N), we examine effects of leptonic CP violation induced by approximate mu-tau symmetric interactions. As long as N is subject to the mu-tau symmetry, we can choose CP phases of Dirac mass terms without loss of generality in such a way that these phases arise from mu-tau symmetry breaking interactions. In the case that no phase is present in heavy neutrino mass terms, leptonic CP phases are controlled by two phases alpha and beta. The similar consideration is extended to N blind to the mu-tau symmetry. It is argued that N subject (blind) to the mu-tau symmetry necessarily describes the normal (inverted) mass hierarchy. We restrict ourselves to mu-tau symmetric textures giving the tri-bimaximal mixing and calculate flavor neutrino masses to estimate CP-violating Dirac and Majorana phases as well as neutrino mixing angles as functions of alpha and beta. Since alpha and beta are generated by mu-tau symmetry breaking interactions, CP-violating Majorana phase tends to be suppressed and is found to be at most O(0.1) radian. On the other hand, CP-violating Dirac phase tends to show a proportionality to alpha or to beta.

28 pages including 14 figures, several typos corrected, version to appear in Phys. Rev. D

References in corpus (8)

• Tri-bimaximal Neutrino Mixing and Flavor-dependent Resonant Leptogenesis
• Neutrino Masses, Lepton Flavor Mixing and Leptogenesis in the Minimal Seesaw Model
• Grand unification of $\mu -\tau$ Symmetry
• Fermion Mass Hierarchies and Flavour Mixing from a Minimal Discrete Symmetry
• Connecting Leptogenesis to CP Violation in Neutrino Mixings in a Tri-bimaximal Mixing model
• Two Categories of Approximately mu-tau Symmetric Neutrino Mass Textures
• $\mu -\tau$ Symmetry and Radiatively Generated Leptogenesis
• Correlation between Leptonic CP Violation and mu-tau Symmetry Breaking

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• Implications of Leptonic Unitarity Violation at Neutrino Telescopes
• Fermion Mass Hierarchies and Flavour Mixing from a Minimal Discrete Symmetry
• A Generic Diagonalization of the 3X3 Neutrino Mass Matrix and Its Implications on the mu-tau Flavor Symmetry and Maximal CP Violation
• Tetra-maximal Neutrino Mixing and Its Implications on Neutrino Oscillations and Collider Signatures
• Softly broken $\mu \leftrightarrow \tau$ symmetry in the minimal see-saw model
• Bi-pair Neutrino Mixing
• Flavor Neutrino Masses giving sinθ_{13}=0
• Leptonic CP Violation Phases, Quark-Lepton Similarity and Seesaw Mechanism
• Lepton Flavor Violation in Complex SUSY Seesaw Models with Nearly Tribimaximal Mixing