Leptonic CP violation induced by approximately μ-τ symmetric seesaw mechanism

Teppei Baba and Masaki Yasuè
Phys. Rev. D 77, 075008 – Published 24 April 2008

Abstract

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

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  • Received 15 October 2007

DOI:https://doi.org/10.1103/PhysRevD.77.075008

©2008 American Physical Society

Authors & Affiliations

Teppei Baba* and Masaki Yasuè

  • Department of Physics, Tokai University, 1117 Kitakaname, Hiratsuka, Kanagawa 259-1292, Japan

  • *7atrd014@keyaki.cc.u-tokai.ac.jp
  • yasue@keyaki.cc.u-tokai.ac.jp

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Issue

Vol. 77, Iss. 7 — 1 April 2008

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