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The Symmetry behind Extended Flavour Democracy and Large Leptonic Mixing

G. C. Branco·J. I. Silva-Marcos
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Abstract

We show that there is a minimal discrete symmetry which leads to the extended flavour democracy scenario constraining the Dirac neutrino, the charged lepton and the Majorana neutrino mass term ($M_R$) to be all proportional to the democratic matrix, with all elements equal. In particular, this discreet symmetry forbids other large contributions to $M_R$, such as a term proportional to the unit matrix, which would normally be allowed by a $S_{3L}\times S_{3R}$ permutation symmetry. This feature is crucial in order to obtain large leptonic mixing, without violating 't Hooft's, naturalness principle.

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G. C. Branco, J. I. Silva-Marcos. 2001-06-12. The Symmetry behind Extended Flavour Democracy and Large Leptonic Mixing. https://doi.org/10.1016/s0370-2693(01)01472-1

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