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From hierarchical to partially degenerate neutrinos via type II upgrade of type I see-saw models

From hierarchical to partially degenerate neutrinos via type II upgrade of type I see-saw models
From hierarchical to partially degenerate neutrinos via type II upgrade of type I see-saw models
We propose a type II upgrade of type I see-saw models leading to new classes of models where partially degenerate neutrinos are as natural as hierarchical ones. The additional type II contribution to the neutrino mass matrix, which determines the neutrino mass scale, is forced to be proportional to the unit matrix by a SO(3) flavour symmetry. The type I see-saw part of the neutrino mass matrix, which controls the mass squared differences and mixing angles, may be governed by sequential right-handed neutrino dominance and a natural alignment for the SO(3)-breaking vacuum. We focus on classes of models with bi-large mixing originating from the neutrino mass matrix although we also briefly discuss other classes of models where large mixing stems from the charged lepton mass matrix. We study renormalization group corrections to the neutrino mass squared differences and mixings and find that the low energy values do not depend sensitively on the high energy values for partially degenerate neutrinos with a mass scale up to about 0.15 eV. Our scenario predicts the effective mass for neutrinoless double beta decay to be approximately equal to the neutrino mass scale and therefore neutrinoless double beta decay will be observable if the neutrino mass spectrum is partially degenerate. We also find that all observable CP phases become small as the neutrino mass scale increases.
0550-3213
239-268
Antusch, Stefan
6a8c0380-78ea-4bcb-afad-4348d84eafba
King, Steve F.
f8c616b7-0336-4046-a943-700af83a1538
Antusch, Stefan
6a8c0380-78ea-4bcb-afad-4348d84eafba
King, Steve F.
f8c616b7-0336-4046-a943-700af83a1538

Antusch, Stefan and King, Steve F. (2005) From hierarchical to partially degenerate neutrinos via type II upgrade of type I see-saw models. Nuclear Physics B, 705 (1/2), 239-268. (doi:10.1016/j.nuclphysb.2004.10.049).

Record type: Article

Abstract

We propose a type II upgrade of type I see-saw models leading to new classes of models where partially degenerate neutrinos are as natural as hierarchical ones. The additional type II contribution to the neutrino mass matrix, which determines the neutrino mass scale, is forced to be proportional to the unit matrix by a SO(3) flavour symmetry. The type I see-saw part of the neutrino mass matrix, which controls the mass squared differences and mixing angles, may be governed by sequential right-handed neutrino dominance and a natural alignment for the SO(3)-breaking vacuum. We focus on classes of models with bi-large mixing originating from the neutrino mass matrix although we also briefly discuss other classes of models where large mixing stems from the charged lepton mass matrix. We study renormalization group corrections to the neutrino mass squared differences and mixings and find that the low energy values do not depend sensitively on the high energy values for partially degenerate neutrinos with a mass scale up to about 0.15 eV. Our scenario predicts the effective mass for neutrinoless double beta decay to be approximately equal to the neutrino mass scale and therefore neutrinoless double beta decay will be observable if the neutrino mass spectrum is partially degenerate. We also find that all observable CP phases become small as the neutrino mass scale increases.

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Published date: 17 January 2005

Identifiers

Local EPrints ID: 56979
URI: http://eprints.soton.ac.uk/id/eprint/56979
ISSN: 0550-3213
PURE UUID: ab53ef0a-c92e-4c34-a462-018bc7e5925b

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Date deposited: 13 Aug 2008
Last modified: 13 Mar 2019 20:34

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Author: Stefan Antusch
Author: Steve F. King

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