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Journal Article

#### "Hidden" O(2) and SO(2) Symmetry in Lepton Mixing

##### MPS-Authors

##### Locator

http://dx.doi.org/10.1007/JHEP02(2012)094

(Publisher version)

##### Fulltext (public)

1112.3628

(Preprint), 2MB

##### Supplementary Material (public)

There is no public supplementary material available

##### Citation

Heeck, J., & Rodejohann, W. (2012). "Hidden" O(2) and SO(2) Symmetry in Lepton
Mixing.* Journal of High Energy Physics,* *1202*(2): 094.
doi:10.1007/JHEP02(2012)094.

Cite as: http://hdl.handle.net/11858/00-001M-0000-000F-4B3E-8

##### Abstract

To generate the minimal neutrino Majorana mass matrix that has a free solar
mixing angle and Delta m_sol^2 = 0 it suffices to implement an O(2) symmetry,
or one of its subgroups SO(2), Z_N (N>2), or D_N (N>2). This O(2) generalizes
the hidden Z_2^s of lepton mixing and leads in addition automatically to mu-tau
symmetry. Flavor-democratic perturbations, as expected e.g. from the Planck
scale, then result in tri-bimaximal mixing. We present a minimal model with
three Higgs doublets implementing a type-I seesaw mechanism with a spontaneous
breakdown of the symmetry, leading to large theta_13 and small Delta m_sol^2 =
0 due to the particular decomposition of the perturbations under mu-tau
symmetry.