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Phased breaking of μ − τ symmetry and leptogenesis

2006; American Physical Society; Volume: 73; Issue: 9 Linguagem: Inglês

10.1103/physrevd.73.093005

1550-7998

Y. H. Ahn, Sin Kyu Kang, C. S. Kim, Jake Lee,

Astrophysics and Cosmic Phenomena

Nonvanishing ${U}_{e3}$ has been theoretically related to a certain flavor symmetry breaking in the neutrino sector. We propose a scenario to break the $\ensuremath{\mu}\ensuremath{-}\ensuremath{\tau}$ symmetry so as to accommodate the nonvanishing ${U}_{e3}$. Our scenario is constructed in the context of a seesaw model, and the $\ensuremath{\mu}\ensuremath{-}\ensuremath{\tau}$ symmetry breaking is achieved by introducing a $CP$ phase in the Dirac Yukawa matrix. We also show how the deviation of ${\ensuremath{\theta}}_{23}$ from the maximal mixing and nonvanishing ${U}_{e3}$ depend on the $CP$ phase. Neutrino mixings and the neutrino mass-squared differences are discussed, and the amplitude in neutrinoless double beta decay ${m}_{ee}$ are also predicted. We found that a tiny breaking of the $\ensuremath{\mu}\ensuremath{-}\ensuremath{\tau}$ symmetry due to mass splitting between two degenerate heavy Majorana neutrinos on top of the Dirac $CP$ phase can lead to successful leptogenesis. We examine how leptogenesis can be related with low energy neutrino measurement, and show that our predictions for ${U}_{e3}$ and ${m}_{ee}$ can be constrained by the current observation of baryon asymmetry.