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New Weinberg operator for neutrino mass and its seesaw origin

New Weinberg operator for neutrino mass and its seesaw origin
New Weinberg operator for neutrino mass and its seesaw origin

We consider a new Weinberg operator for neutrino mass of the form HudLiLj involving two different Higgs doublets Hu, Hd with opposite hypercharge, where H˜ sd is the charge conjugated doublet. It may arise from a model where the two Higgs doublets carry the same charge under a U(1) gauge group which forbids the usual Weinberg operator but allows the mixed one. The new Weinberg operator may be generated via two right-handed neutrinos oppositely charged under the U(1), which may be identified as components of a fourth vector-like family in a complete model. Such a version of the type I seesaw model, which we refer to as type Ib to distinguish it from the usual type Ia seesaw mechanism which yields the usual Weinberg operator, allows the possibility of having potentially large violations of unitarity of the leptonic mixing matrix whose bounds we explore. We also consider the relaxation of the unitarity bounds due to the further addition of a single right-handed neutrino, neutral under U(1), yielding a usual type Ia seesaw contribution.

Beyond Standard Model, Neutrino Physics, Solar and Atmospheric Neutrinos
1126-6708
Hernandez-Garcia, Josu
a369a2bd-30f0-4c00-922f-0cff293bd9cb
King, Stephen F.
f8c616b7-0336-4046-a943-700af83a1538
Hernandez-Garcia, Josu
a369a2bd-30f0-4c00-922f-0cff293bd9cb
King, Stephen F.
f8c616b7-0336-4046-a943-700af83a1538

Hernandez-Garcia, Josu and King, Stephen F. (2019) New Weinberg operator for neutrino mass and its seesaw origin. Journal of High Energy Physics, 2019 (5), [169]. (doi:10.1007/JHEP05(2019)169).

Record type: Article

Abstract

We consider a new Weinberg operator for neutrino mass of the form HudLiLj involving two different Higgs doublets Hu, Hd with opposite hypercharge, where H˜ sd is the charge conjugated doublet. It may arise from a model where the two Higgs doublets carry the same charge under a U(1) gauge group which forbids the usual Weinberg operator but allows the mixed one. The new Weinberg operator may be generated via two right-handed neutrinos oppositely charged under the U(1), which may be identified as components of a fourth vector-like family in a complete model. Such a version of the type I seesaw model, which we refer to as type Ib to distinguish it from the usual type Ia seesaw mechanism which yields the usual Weinberg operator, allows the possibility of having potentially large violations of unitarity of the leptonic mixing matrix whose bounds we explore. We also consider the relaxation of the unitarity bounds due to the further addition of a single right-handed neutrino, neutral under U(1), yielding a usual type Ia seesaw contribution.

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Accepted/In Press date: 18 May 2019
e-pub ahead of print date: 27 May 2019
Keywords: Beyond Standard Model, Neutrino Physics, Solar and Atmospheric Neutrinos

Identifiers

Local EPrints ID: 431793
URI: http://eprints.soton.ac.uk/id/eprint/431793
ISSN: 1126-6708
PURE UUID: 1a263ca2-e1ab-45ec-95a6-458a6c7c013d

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Date deposited: 17 Jun 2019 16:30
Last modified: 07 Oct 2020 00:38

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